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Hoyt, Cathryn A. "Grassland to desert : Holocene vegetation and climate change in the northern Chihuahuan Desert /." Digital version:, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p9992819.
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Fallahi, Esmaeil, Mike Kilby, and Phil Tilt. "Adaptation of Deciduous Fruit to the Desert Climate." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/215696.
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Chilling requirements and maturity of several varieties of peaches and apples were studied at the University of Arizona, Yuma Mesa Agricultural Center (Southwest Arizona) in 1985-1986. Flordared, Flordabelle, Flordabeauty, Flordagold, Desert Gold and Suwanee peaches broke their dormancy earlier than other cultivars and showed full bloom between mid-to-late January. Suwanee and Desert Gold matured earlier than other tested varieties, but they produced small size fruit with low sugar content. Anna and Dorsett Golden apples showed extended blooming period due to insufficient chilling.
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Al-Taie, Laith. "Performance of Clay Liners in Near-Surface Repositories in Desert Climate." Doctoral thesis, Luleå tekniska universitet, Geoteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26615.
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Wars in Iraq (1991 and 2003) generated various types of hazardous waste (HW) in the form of soil contaminated by depleted uranium (DU). Other HW emanated from destroyed army vehicles and remnants of Iraqi nuclear facilities holding various types and amounts of chemical and radioactive material. The negative impact of the various wastes on the health conditions of the population was reported from different parts of Iraq, showing an enhanced frequency of cancer and abnormally born infants. For isolating the wastes, which represent low-level and short-lived intermediate level radioactive wastes, near-surface repositories (NSR) are proposed since they represent the least expensive way of solving future problems with sufficient safety. Internationally, the timeframe of the containment of such wastes is designated to be 300 years. Site selection affects and largely controls the selection of a suitable design the aim being to minimize or eliminate migration of hazardous elements from the waste to the environment. The formulation of siting criteria is the first vital step toward the resolution of the problem. Site selection criteria are proposed taking in account three major factors: environmental, geological and socio-economic factors. Accordingly, Iraqi deserts, which make up 60% of Iraq, represent the number one candidate for locating a safe disposal facility, primarily because of the low population, suitable topography, climatic conditions, seismic stability and availability of raw materials. Long-term performance of NSR is directly related to the function of top and bottom liner systems. They should be designed so that they are mutually compatible and combine to effectively isolate the waste. Liners are considered as the main elements of any disposal facility on the ground surface and a properly designed top liner system is of particular importance since it will minimize or eliminate water percolation into the waste body. Compacted clay liners (CCL) should preferably have with a low hydraulic conductivity, which is achievable by proper selection of raw materials, compaction density and construction methods. A further criterion is that they must not soften significantly by expansion on wetting, which puts a limit to the smectite content and density. The liners can consist of native material found near the landfill site, and be used after simple processing, primarily drying and crushing, or be mixed with fillers like silty sand. Since the hydraulic conductivity is the key property of a reliable CCL, relevant experimental determination of the hydraulic conductivity is vital. The common practice in geotechnical laboratories is to apply high hydraulic gradients for getting results quickly but this can lead to non-conservative, incorrect results. The present study involved determination of the hydraulic conductivity of a smectite-rich clay sampled at places within reasonable distance from potential NSR sites. Various hydraulic gradients were applied to samples compacted to several different densities, using two permeants and two filter types. It was concluded that the outflow filter can significantly affect the evaluated conductivity especially when applying high hydraulic gradients. This was partly explained by clogging of outflow filters of conventional fine-porous type by torn-off clay particles at such gradients. A major conclusion was that the gradient in laboratory testing should not exceed 100 m/m.In order to assess the suitability of available raw materials within the Iraqi Deserts, two smectitic soils termed as Green and Red clays were investigated for potential use in CCLs. Both clays are fairly rich in smectite, which calls for mixing them with properly graded silt/sand material from the desert for modifying the expandability. The shear strength, swelling pressure, hydraulic conductivity and creep properties were determined and used for defining criteria for selecting suitable clay-sand ratios. The results showed that 30-50% Green clay mixed with sand and 40-60% Red clay mixed with sand were suitable for constructing top liners with a hydraulic conductivity of 1×10-9 - 1×10-10 m/s. For bottom liners, 70% Green clay mixed with sand and 80% Red clay mixed with sand would be suitable; they were found to have a hydraulic conductivity of 1×10-11 m/s.The long-term performance of CCL is controlled by a number of processes like long periods of extreme dryness and short periods of very heavy rain. The percolation of water through the top liner system of a number of design alternatives were simulated using the code HELP 3.95D and subsequently by the FE program VADOSE/W. For the assumed NSR concept the slope stability of the top liner is essential and it was determined by using FE technique considering various slope angles. The engineering properties, primarily the hydraulic conductivity, swelling pressure and shear strength of 30-50% Green clay mixed with sand were introduced in the simulations. Two initial water contents of the compacted materials were considered representing 1) optimum water content (“wet case”), and 2) air‐dry conditions (“dry case”). Application of the HELP code decided the selection of suitable CCL having a thickness of 0.5 m and inclined by 5.7ᵒ. More detailed analyses with VADOSE/W showed that a mixture at the dry case would bring 0.5 mm (0.5 litre of leaking water per square meter) through CCL in an eight year simulation period. Long-term simulations (up to 300 years) showed that CCL would undergo continuous drying without reaching saturation even in the case of periods of very heavy rain (616 mm) for the wet and dry cases. The slope stability factor for the rather steep angle 30ᵒ was found to be 1.5 for the most critical case representing complete water saturation. In conclusion, the proposed materials and design features are believed to be suitable for practical application.Godkänd; 2014; 20140924 (laikha); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Laith Al-Taie Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Avhandling: Performance of Clay Liners in Near-Surface Repositories in Desert Climate Opponent: Professor Frank Wagner, University of Trier, Department of Geology, Tyskland Ordförande: Professor Sven Knutsson, Avd för geoteknologi, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Onsdag den 3 december 2014, kl 13.00s Plats: F1031, Luleå tekniska universitet
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Lim, Sophak. "50,000 years of vegetation and climate change in the Namib Desert." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT150/document.
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Cette thèse présente les données des pollens et micro-charbons fossiles couvrant la période des 50 000 dernières années à partir de sites sélectionnés transversalement nord-sud du désert de Namib. Dans le cadre de cette thèse, on utilise le rock hyrax middens, l’accumulation des boulettes et des urines fossilisés du Procavia capensis, représentant une excellente archive pour archives pour la préservation des pollens et micro-charbons à long-terme. Trois sites des hyrax middens ont été sélectionnés pour l'analyse: au sud du désert de Namib (Pella), la marge est des dunes de sable de Namib (Zizou) et le centre de la Namib (Spitzkoppe). En plus, le régime pluvial de ces sites se caractérise par une forte variabilité annuelle et interannuelle. En conséquence, tous ces sites se situent au long de l’écotone du Désert et du biome Nama-Karoo, ainsi qu'à l’est (biome de Savane). Alors que ces sites sont répertoriés dans des écosystèmes similaires, l’écotone, lui, est considéré comme une zone potentiellement très sensible au changement du système climatique régional. Un intérêt spécifique de ces enregistrements terrestres est pour évaluer s’ils corroborent ou s’opposent avec les résultats provenant ceux des sédiments marins de la côte namibienne, en particulier la conclusion : l’abondance des taxa dominants du Fynbos Biome du Cape peut indiquer significativement une expansion vers le nord de la flore du Cape pendant les périodes plus froides glaciaires. Selon les sites d’études sélectionnées, les conclusions principales de ce travail sont les suivantes:Les hyrax middens de Pella fournissent le premier enregistrement pollinique continué au sud du désert de Namib durant la période des 50 000 dernières années. Ces données polliniques ont permis de reconstruire le changement de la végétation et d'estimer la température et l'aridité. Les résultats indiquent que la période glaciaire se caractérise par une augmentation de la disponibilité de l'eau sur le site par rapport à l'Holocène. Les changements de la température et de l'évapotranspiration potentielle semblent avoir joué un rôle important dans la détermination de l'équilibre hydrologique.L'enregistrement de Zizou hyrax midden met en évidence des changements de la végétation à la marge l'est des dunes de sable depuis 38 000 ans cal BP. La végétation de la période glaciaire se caractérise par les pourcentages relativement élevés des Astéracées pollen, et plus particulièrement par des taxa du climat plus froid: Stoebe et Artemisia¬-type. En accord avec les données de Pella, le réchauffement au début de l'Holocène indiqué par la dominance de pollen des graminées dans l'assemblage pollinique suggère une expansion du biome de Désert.Les hyrax middens de Spitzkoppe enregistrent les changements de la végétation dans le centre du désert de Namib au cours des 32 000 dernières années. Les résultats sont globalement cohérents en comparant aux autres enregistrements terrestres dans la région. L'analyse de ces données n'est cependant pas encore terminée.Dans tous ces sites, une variabilité significative a été observée à la fois dans la dernière période glaciaire et l'Holocène. Les conditions plus froides de l'ère glaciaire semblent être caractérisées par une augmentation de la disponibilité de l'eau le long de la totalité de notre zone d'étude. Au contraire des résultats provenant des carottes marines, nos enregistrements indiquent aucune expansion de la végétation de Fynbos biome, et seulement des traces de Restionaceae pollen dans le site extrêmement au sud à Pella (pas plus de 1%), mais aucun trace de ce pollen n'ayant été observé à Zizou ainsi qu’à SpitzkoppeThis thesis presents fossil pollen and microcharcoal data during the last 50,000 years from a north-south transect of the Namib Desert. The arid environment of the Namib precludes the development of permanent wetlands, and as a result few palaeoenvironmental records exist from the region. In this study, we employ rock hyrax middens – fossilised accumulations of the faecal pellets and urine of the Procavia capensis. Hyrax middens from three sites were selected for analysis: the southern Namib (Pella), the eastern margin of Namib Sand Sea (Zizou), and the central Namib (Spitzkoppe). The results from these terrestrial sites are the extent to which they may corroborate or conflict with findings from pollen records obtained from marine sediments of the Namibian coast.The Pella hyrax middens provide the first continuous pollen record from the southern Namib Desert since the last 50,000 years, and are used to reconstruct vegetation change and quantitative estimates of temperature and aridity. Results indicate that the last glacial period was characterised by increased water availability relative to the Holocene. Changes in temperature and potential evapotranspiration appear to have played a significant role in determining the hydrologic balance. The record can be considered in two sections: 1) the last glacial period, when low temperatures favoured the development of more mesic Nama-Karoo vegetation at the site, with periods of increased humidity concurrent with increased coastal upwelling, both responding to lower global/regional temperatures; and 2) the Holocene, high temperatures and potential evapotranspiration resulted in increased aridity and an expansion of the Desert Biome.Considered in the context of discussions of forcing mechanisms of regional climate change and environmental dynamics, the results from Pella stand in clear contrast with many inferences of terrestrial environmental change derived from regional marine records. Observations of a strong precessional signal and interpretations of increased humidity during phases of high local summer insolation in the marine records are not consistent with the data from Pella. Similarly, while high percentages of Restionaceae pollen has been observed in marine sediments during the last glacial period, they do not exceed 1% of the assemblage from Pella, indicating that no significant expansion of the Fynbos Biome has occurred during the last 50,000 years.The Zizou hyrax midden highlights vegetation changes on the eastern margin of the Namib Sand Sea since 38,000 cal BP. Results show the different vegetation compositions between the last glacial period and the Holocene. Glacial vegetation characterised with relatively high percentages of Asteraceae pollen, particularly cool climate taxa such as Stoebe and Artemisia types. Similar to the data from Pella, with the onset of Holocene warming grass pollen comes to dominate the assemblage, suggesting an expansion of the Desert Biome. We suggest that the climate during the last glacial period was more humid, and supported the development of shrubs/small trees. Arid conditions during the Holocene saw the depletion of this resource, and the development of grasslands that could exploit the rare rains that the region experiences today. In common with the Pella record, no elements of the Cape flora are found in the Zizou middens.The Spitzkoppe hyrax middens record vegetation changes in the central Namib during the last 32,000 years. The last glacial vegetation compositions composed of Olea, Artemisia¬-type, Stoebe¬-type and grasses. In the Holocene, the arboreal taxa such as Olea was replaced by others like Eculea, Dombeya, Commiphora, and Croton¬-type with relative higher percentage of grasses at early Holocene
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Swartley, Joseph B. "Solar Development in the Mojave Desert." Scholarship @ Claremont, 2010. http://scholarship.claremont.edu/cmc_theses/74.
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For more than two centuries, humans have been spewing “greenhouse gases” into the atmosphere through the burning of fossil fuels, deforestation, and the development of land, causing the planet’s surface temperature to increase at an accelerated rate. Climate change is one of the most pressing issues that the world is facing today, and in order to combat the effects of climate change, it is necessary to adopt the use of more renewable technology, namely solar energy. The United States' best region for solar development is the Mojave Desert, and many large-scale projects are being built or proposed to be built in the area. However, the deployment of solar technology in the Mojave Desert comes with significant ecological, socioeconomic, and political impacts. This paper is intended to provide an overview of the issues surrounding solar development in the Mojave Desert.
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Vazquez, Tyara Kiileialohalani. "Physiological Responses to Heat-stress in a Desert Montane Lizard." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544789284098965.
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Sternberg, Troy. "Nomadic geography : pastoral environments in the Gobi Desert, Mongolia." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:bc3b363d-5d7a-4b4c-896d-4296ba99cf43.
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Pastoralism on the Mongolian steppe encompasses limited physical resources and evolving anthropogenic influences. Little-studied, the Inner Asian region encounters changing climates, evolving land use practices, and socio-economic transition that impact the natural and human geography. This thesis investigates how bio-physical factors and herder action determine the pastoral environment in the Gobi Desert, Mongolia. Research, focusing on drought, degradation and the extreme winter conditions that define pastoralism in Mongolia, examines pastoralists' perception of and interaction with their environment. This approach highlights steppe ecological and social processes within the global dryland debate. Fieldwork in Omnogovi and Ovorhangai Province established that drought is endemic in the region. However, drought events were independent of extreme winter conditions and did not exacerbate their impact. Degradation was not found at water points as vegetation cover decreased with distance from water. While remote sensing showed a decline in vegetation cover over time, it did not establish desertification on the steppe. Changing physical, socio-economic, and political conditions since 1990 continue to impact Mongolian pastoralism. Environmental conditions, particularly water resources and pasture quality, were paramount herder concerns. This research showed that pastoralists are economically motivated, differentiate on multiple dimensions, and value communal land stewardship. On the steppe, traditional mobile livestock practices improve livelihoods and remain an effective management approach. However, the future of pastoralism is uncertain as herders settle, the population ages, and children become educated. Thesis results emphasize the interaction of physical and social environments will define pastoralism's role in the Gobi Desert
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Abdu, Salamatu. "Does the availability of shade limit use of water troughs by desert birds?" Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15461.
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Includes bibliographical referencesClimate change poses a major threat to living organisms, with maximum temperatures expected to continue to rise over the next few decades. Hot desert environments are particularly at risk because they experience high environmental temperatures, scarce vegetation, low productivity and unpredictable water sources. Endotherms such as birds face the challenge of maintaining a stable body temperature while avoiding dehydration. This study was carried out in the southern Kalahari, in South Africa's Northern Cape, where about 50% of bird species (36 species) depend on free-standing drinking water. Livestock farms within this area provide artificial water points, which benefit birds as well as livestock. This study determined the role of shade and cover in the use of these artificial water points by birds. An experiment was conducted at six waterholes using the Before-After, Control-Impact (BACI) design. After an initial baseline was established, three waterholes were shaded while the other three were left unshaded. Camera traps were used to record the pattern and intensity of water use by bird species at different times of the day and at varying air temperatures. A total of 36 bird species drank at the water holes, but data analysis was confined to the ten most abundant species. Of the ten, six species responded to the presence of shade/cover, with four species reacting positively (Cape Glossy Starling Lamprotornis nitens , Red - headed Finch Amadina erythrocephala , Black - throated Canary Serinus atrogularis , and Laughing Dove Spilopelia senegalensis ), four showing no significant change in drinking patterns, and two showing a decrease in visitor numbers when the site was shaded (Cape Turtle - Dove Streptopelia capicola, Namaqua Dove Oena capensis). This suggests that providing shade at waterholes is not a universal solution to the problem of increasing heat stress experienced by birds coming to drink. Certain species such as the Laughing Doves and Cape Turtle-Doves avoided waterholes during the warmest time of the day while the Namaqua Doves were frequent visitors at this time. However, the Laughing Dove took advantage of the shade provided at midday (warmest temperatures) as their numbers increased. The Red-headed Finch and Black-throated Canary also increased at water holes with temperature irrespective of the time of day. These patterns imply that the provision of shade modifies the behavior of some bird species in response to predation risk or heat stress. These species utilized shade at different times of day and with varying intensities as temperatures rose.
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Kirchhof, Sebastian, Robyn S. Hetem, Hilary M. Lease, Donald B. Miles, Duncan Mitchell, Johannes Müller, Mark-Oliver Rödel, Barry Sinervo, Theo Wassenaar, and Ian W. Murray. "Thermoregulatory behavior and high thermal preference buffer impact of climate change in a Namib Desert lizard." WILEY, 2017. http://hdl.handle.net/10150/626549.
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Knowledge of the thermal ecology of a species can improve model predictions for temperature-induced population collapse, which in light of climate change is increasingly important for species with limited distributions. Here, we use a multi-faceted approach to quantify and integrate the thermal ecology, properties of the thermal habitat, and past and present distribution of the diurnal, xeric-adapted, and active-foraging Namibian lizard Pedioplanis husabensis (Sauria: Lacertidae) to model its local extinction risk under future climate change scenarios. We asked whether climatic conditions in various regions of its range are already so extreme that local extirpations of P. husabensis have already occurred, or whether this micro-endemic species is adapted to these extreme conditions and uses behavior to mitigate the environmental challenges. To address this, we collected thermoregulation and climate data at a micro-scale level and combined it with micro-and macroclimate data across the species' range to model extinction risk. We found that P. husabensis inhabits a thermally harsh environment, but also has high thermal preference. In cooler parts of its range, individuals are capable of leaving thermally favorable conditions-based on the species' thermal preference-unused during the day, probably to maintain low metabolic rates. Furthermore, during the summer, we observed that individuals regulate at body temperatures below the species' high thermal preference to avoid body temperatures approaching the critical thermal maximum. We find that populations of this species are currently persisting even at the hottest localities within the species' geographic distribution. We found no evidence of range shifts since the 1960s despite a documented increase in air temperatures. Nevertheless, P. husabensis only has a small safety margin between the upper limit of its thermal preference and the critical thermal maximum and might undergo range reductions in the near future under even the most moderate climate change scenarios.
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Dodson, Leslie Lynn. "A foggy desert| Equitable information flow for a fogwater system in southwest Morocco." Thesis, University of Colorado at Boulder, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3621317.
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This dissertation describes the design, implementation and evaluation of a gender-inclusive information system linking rural women in Agni Hiya, Morocco and water project managers from the Association Dar Si-Hmad. This research was motivated by an interest in exploring the linkages between information and communication technologies (ICT), climate change, natural resource management and women's participation in community development in the drought-ridden Aït Baamrane region of southwest Morocco. The research investigates the potential for mobile phones to help address communication constraints that rural Berber women face, including culture, religion, and lack of digital literacy. These issues are relevant to the study and design of a gender-inclusive information system (the "Fog Phone") intended to help manage a fogwater distribution system that will deliver water from the Anti-Atlas Mountains to Berber villages.
The research investigates two similar groups of low-literate, marginalized rural Berber women from the same geographic community who have mobile phones. Technology-focused ethnographic research methods were used to first investigate the social, cultural and technical factors involved in mobile phone use by women employed in an Argan oil Cooperative. Findings from the Argan oil Cooperative study were then applied and expanded in a study of Berber women involved in the operation of the fogwater system. By virtue of their responsibilities as principal water gatherers and water users in the community, Berber women are key stakeholders in the fogwater system. Their continued involvement in water management was extended to the participatory design and development of the prototype Fog Phone.
Cultural conditions restricting communication between unrelated men and women led to an information system design that supported cultural, social, economic and technical constraints. The Fog Phone enabled women to report on the water system using a series of symbols that communicate water system status without violating cultural norms. In addition to an exploration of the relationship between gender and technology, this research explores related themes of climate change and environmental vulnerability as they pertain to women's lives and livelihoods, as well as the ability of rural Berber women to manage the environmental assets on which their livelihoods depend.
The contributions of this research include a prototype information system for the fogwater project; a better understanding of the mobile phone utility gap and its impact on the use of ICT by marginalized women in polyglot and oral-language dependent communities; and advances in the emerging practice of ICTs, Climate Change and Development (ICCD) by providing a case study of the linkages between mobile phones, water resources that are affected by climate change and women in rural communities involved in an environmentally sustainable development project in the Middle East and North Africa—a region that is largely missing from ICCD and overall ICT for Development research.
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Bai, YanYing. "Distribution of soil temperature regimes and climate change in the Mojave Desert region." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957301331&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268844053&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.
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余耀良 and Yiu-leung Yieu. "OSL dating of sediment and climate change of late quaternary." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/192989.
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The objective of this project is to apply the Optical Stimulated Luminescence (OSL) technique to date the palaeo sediment from Mu Us Desert, part of the Inner Mongolia in northern China and reconstruct the palaeo environment. Five OSL samples were collected from Dagouwan, Salawusu River Valley at Inner Mongolia by Dr S. H. Li and his team in 2009. Extraction of 150μm to 180μm silt-size feldspar from collected dune sand, lacustrine facies and fluvial facies samples and running of luminescence dating therefore to obtain the age from 50ka to 90ka. Climate proxies - magnetic susceptibility, grain size, fossil vertebrates and fossil pollens have been analyzed and it is concluded that significant climate change occurred within this period, which change from domination of warm, humid and rainy summer monsoons (before 70ka) to cold, wind, windy strengthened dry winter wind and back to warm and humid again after 55ka.published_or_final_version
Applied Geosciences
Master
Master of Science
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Inman, Richard D. "How elusive behavior and climate influence the precision of density estimates and desert tortoise populations." abstract and full text PDF (free order & download UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1453581.
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Haug, Erik William. "Climatic and Geomorphic Interactions on Alluvial Fans in the Atacama Desert, Chile." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32589.
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Alluvial fan surfaces in the Atacama Desert of northern Chile preserve evidence of recent, precipitation-driven, surface flows. Determining the hydrologic characteristics of these flows is important for understanding the effects of rare yet significant storms in the region. Flow reconstruction, runoff analysis, and comparison with climatological data yield surface activation recurrence intervals of ~1-20 years for three small fans and associated catchments proximal to Iquique and Antofagasta. Relatively short-lived and intense precipitation events (1-3 hour, > 4 mm/hr) are required to mobilize and transport the largest surface grains. Modeled discharges provide minimum constraints on the rates of precipitation that yield surface-forming flows in the hyper-arid region. The results of this study aid in understanding the evolution of various surfaces in the region. In particular, results provide a clear indication of the ability of a particular storm event --i.e., precipitation rate to activate a surface.Master of Science
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Cavazos, Guerra C. d. C. "Modelling the atmospheric controls and climate impact of mineral dust in the Sahara Desert." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1322565/.
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Mineral dust aerosols play an important role in climate and the Earth's energy budget. The effect of dust on the radiative forcing is uncertain due to the complexity of particle properties and the complexity to quantify and discriminate preferential dust sources. This research considers the potential of two Regional Climate Models (RCM’s): The Weather Research and Forecasting model (WRF-Chem) and the Regional Climate Model (RegCM3) both with an integrated dust module. Numerical sensitivity experiments are performed to quantify the ability of both models to simulate sources, the magnitude of dust emission, the transport in 3-dimensions and the subsequent impact on the radiative forcing. Particular emphasis is given to preferential source regions within the Sahara and Sahel in North Africa including the Bodélé Depression in Northern Chad. To account for the distribution of preferential dust source regions, soil texture characteristics were modified in dust source regions in RegCM3. As for WRF-Chem GOCART scheme, a new higher resolution erodible fraction map is tested. Moreover, the sensitivity of the results to the specification of aerosol optical properties to evaluate the impacts of optical characteristics on the radiative forcing was considered for the RegCM3. Finally, model outputs are compared to in-situ data: weather stations (WMO) and AERONET and satellite estimates: MODIS, MISR, OMI, CALIPSO and SEVIRI. Results show that both models represent the space/time structure of near-surface meteorology well. The tuning of preferential dust sources tested in this research provides a more realistic representation of local dust sources, emissions and resulting AOT. This suggest that in the absence of truly accurate soil maps at high resolution, further refinements to preferential sources map and its implementation in dust models can lead to useful improvements in simulation of dust processes and dust forecast accuracy.
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Wahl, Emma. "Buildings in Arid Desert Climate : Improving Energy Efficiency with Measures on the Building Envelope." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62703.
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Because of the harsh climate of Saudi Arabia, residential buildings on average, consume more than half of the total consumed energy. A substantial share of energy goes to the air-conditioning of buildings. Cooling buildings during summer is a major environmental problem in many Middle Eastern countries, especially since the electricity is highly dependent on fossil fuels. The aim of this study is to obtain a clearer picture of how various measures on the building envelope affects the buildings energy consumption, which can be used as a tool to save energy for buildings in the Middle East. In this study, different energy efficiency measures are evaluated using energy simulations in IDA ICE 4.7 to investigate how much energy can be saved by modifying the building envelope. A two-storey residential building with 247 m2 floor area is used for the simulations. The measures considered are; modifications of the external walls, modification of the roof, window type, window area/distribution, modification of the foundation, shading, exterior surface colour, infiltration rate and thermal bridges. All measures are compared against a base case where the building envelope is set to resemble a typical Saudi Arabian residential. First, all measures are investigated one by one. Thereafter, combinations of the measures are investigated, based on the results from single measure simulations. All simulations are carried out for two cities in Saudi Arabia, both with arid desert climate. Riyadh (midlands) with moderately cold winters and Jeddah (west coast) with mild winter. The results from simulations of single measures show the highest energy savings when changing the window type from single clear glass to double glass with reflective surface saving 27 % energy (heating & cooling) in Riyadh and 21 % in Jeddah. Adding insulation to an uninsulated roof saved up to 23 % and 21 % energy for Riyadh respectively Jeddah. Improvements of the thermal resistance of the exterior walls show 21 % energy savings in Riyadh and only 11 % in Jeddah. Lowering the window to wall ratio from 28 % to 10 % and changing the window distribution results in 19 % (Riyadh) and 17 % (Jeddah) energy savings. Adding fixed shades saves up to 8 % (Riyadh) and 13 % energy (Jeddah) when dimensioned for the peak cooling load. Using bright/reflective surface colour on the roof saves up to 9% (Riyadh) and 17 % (Jeddah) when the roof is uninsulated. For the exterior walls, bright/reflective surface saves up to 5 % (Riyadh) and 10 % (Jeddah) when the walls are uninsulated. The other single measures investigated show less than 7 % energy savings. The results for combined measures show the highest energy savings for two combined measures when improving the thermal resistance of the exterior walls and changing window area/distribution saving up to 52 % (Riyadh) and 39 % (Jeddah). When performing three measures the addition of improved thermal resistance and reflectance of the windows resulted in the highest energy savings, saving up to 62 % (Riyadh) and 48 % (Jeddah). When adding a fourth measure, improving the thermal resistance of the slab shows the highest energy savings, 71 % (Riyadh) and 54 % (Jeddah). Applying all measures on the building envelope results in 78 % (Riyadh) and 62 % (Jeddah) energy savings. Significant energy savings can be achieved with measures on the building envelope. Major savings can be made by adding only 50-100 mm of insulation to the exterior walls and roof. Decreased window area and improvements on the thermal resistance and reflectance on the windows result in significant energy savings. Energy savings achieved with shadings and reflective surface colours decrease significantly when the thermal resistance of the roof and external walls are improved. All measures concerning thermal resistance have a higher impact in Riyadh than in Jeddah due to that a large part of the total heating and cooling is air handling unit (AHU) cooling in Jeddah. AHU cooling is not affected significantly by measures on the building envelope. To optimise energy savings, measures on the building envelope should be considered in combination with measures concerning the AHU.På grund av det hårda klimatet i Saudiarabien, konsumerar bostadshus mer än hälften av den totala energi som förbrukas. En stor del av den förbrukade energin går till luftkonditionering. Kylningen av byggnader är ett stort miljöproblem i många länder i Mellanöstern, särskilt eftersom elektriciteten till stor del är helt beroende av förbränning av fossila bränslen. Syftet med denna studie är att få en tydligare bild av hur olika åtgärder på klimatskalet påverkar byggnaders energiförbrukning. Tanken är att resultaten ska kunna användas som ett hjälpmedel vid design av mer energieffektiva byggnader i Mellanöstern. I denna studie är olika energieffektivitetsåtgärder utvärderade med hjälp av energisimuleringar i IDA ICE 4.7 för att undersöka hur mycket energi som kan sparas genom att modifiera klimatskalet. Ett bostadshus med 247 m2 golvyta i två våningar används för simuleringarna. De åtgärder som övervägs är; modifieringar av ytterväggar, modifiering av tak, fönstertyp, fönster area/ distribution, modifiering av fundamentet, skuggning, ytskikt, infiltration och köldbryggor. Alla åtgärder jämförs mot ett Base Case där klimatskalet är inställt för att likna en typisk bostad i Saudiarabiens. Först undersöks alla åtgärder en åt gången. Därefter undersöks kombinationer av de studerade åtgärderna, baserat på resultat från simuleringar av enskilda åtgärder. Alla simuleringar utförs för två städer i Saudiarabien, både med torrt ökenklimat. Riyadh (inlandet) med måttligt kalla vintrar och Jeddah (västkusten) med mild vinter. Resultatet från simuleringar av enskilda åtgärder visar högst energibesparing när fönstertypen byts ut från enkelt klarglas till dubbelt reflekterande glas. Med byte av fönstertyp sparas upp till 27 % energi (uppvärmning och kylning) i Riyadh och 21 % i Jeddah. Att isolera taket sparar upp till 23 % och 21 % för Riyadh respektive Jeddah. Förbättrat värmemotstånd i ytterväggarna resulterar i upp till 21 % energibesparing i Riyadh och endast 11 % i Jeddah. Minskning av fönsterarean från 28 % av väggytan till 10 % och omplacering av fönsterna ger19 % (Riyadh) och 17 % (Jeddah) energibesparingar. Solavskärmning med hjälp av fasta skärmtak och fenor sparar 8 % (Riyadh) och 13 % energi (Jeddah) när de är dimensionerad för maximalt kylbehovet. Använda ljus/reflekterande yta på taket sparar upp till 9 % (Riyadh) och 17 % (Jeddah) när taket är oisolerad. För ytterväggar, sparar ljust/reflekterande ytskikt upp till 5 % (Riyadh) och 10 % (Jeddah) när väggarna är oisolerad. De övriga enskilda åtgärderna som undersökts visar mindre än 7 % energibesparing. Resultaten för kombinerade åtgärder visar högst energibesparingar för två kombinerade åtgärder när ytterväggens värmemotstånd förbättras tillsammans med mindre fönsterarea och ändrad fönsterplacering. De två åtgärderna sparar upp till 52 % energi i Riyadh och 39 % i Jeddah. När tre åtgärder utförs, fås den högsta energibesparingen med de två åtgärderna ovan med tillägg av förbättrade fönster med lägre u-värde och högre reflektants. Tillsammans resulterar de tre åtgärderna i en energibesparing upp till 62 % för Riyadh och 48 % för Jeddah. När man lägger till en fjärde åtgärd, fås den högsta besparingen med tillägg av förbättrat u-värde på grunden till de tre tidigare åtgärderna. De fyra åtgärderna sparar upp till 71 % energi i Riyadh och 54 % i Jeddah. Tillämpning av alla åtgärder på klimatskalet resulterar i 78 % (Riyadh) och 62 % (Jeddah) energibesparing. Betydlig reducering av energianvändningen kan uppnås med åtgärder på byggnadens klimatskal. Stora besparingar fås med endast 50 – 100 mm isolering i ytterväggar och tak. Att minska fönsterarean och förbättra fönsternas u-värde och reflektivitet bidrar till stora energibesparingar. Besparingarna som fås vid solavskärmning och reflektiva ytor på tak och väggar minskar signifikant när taket och ytterväggarna isoleras. Alla åtgärder som förbättrar u-värdet på klimatskalet har en större inverkan i Riyadh än i Jeddah på grund av att en större andel av total uppvärmning och kylning upptas av kylning av inkommande luft i ventilationen. Energin som behövs för att kyla inkommande luft påverkas inte nämnvärt av åtgärderna på klimatskalet. För att optimera energibesparingarna ytterligare, bör åtgärder på klimatskalets övervägas tillsammans med energieffektivitetsåtgärder av ventilationen.
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Tully, Craig David. "Holocene Mega-Droughts in the Central Atacama Desert, Chile." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1272312883.
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Shepard, Christopher. "Soil Modulation of Ecosystem Response to Climate Forcing and Change Across the US Desert Southwest." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/323416.
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The dryland ecosystems of the US Desert Southwest (SW) are dependent on soil moisture for aboveground productivity; the generation of soil moisture in the SW is dependent on both soil physical properties and climate forcing. This study is one of the first regional point-scale analyses that explores the role of soil physical properties in modulating aboveground vegetation dynamics in response to climate forcing in the SW. Soil texture accounted for significant differences in average aboveground primary productivity across the SW. However, soil texture could not account for differences in inter-annual aboveground productivity variation across the SW. Subsurface soil texture was tightly coupled with precipitation seasonality in accounting for differences in long-term average seasonal aboveground productivity in the Mojave and Sonoran Deserts. The results of this study indicate that the subsurface is a significant factor in modulating aboveground primary productivity, and needs to be included in future modeling exercises of dryland ecosystem response to climate forcing and change.
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Yue, Wenyun. "How do open space and climate influence human activity in public open space in desert regions? /." Sede Boqer : Ben Gurion University of the Negev, Jacob Blaustein Institutes for Desert Research, Albert Katz International School for Desert Studies, 2008. http://aranne5.lib.ad.bgu.ac.il/others/YueWenyun.pdf.
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Nicoll, Kathleen Ann. "Holocene playas as sedimentary evidence for recent climate change in the presently hyperarid western desert, Egypt." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282835.
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Integrated lithostratigraphic and geochronologic studies of Umm Akhtar Playa, a newly discovered dry lake located at ≈ N 22° 36' E 30° 18' in s. Egypt, indicate the accumulation and rapid desiccation of a sizeable (>65 km²) standing water body during the Late Quaternary. An optical date of 15,120 cal yr on basal aeolian sediments indicates that the deflation basin was mantled with aeolian sands during the Late Pleistocene. Overlying Holocene fluvio-lacustrine muds and gravels attests to the former availability of ponded runoff waters at this now-hyperarid locality. Playa waters were deep and persistent enough to create beach berms composed of well-rounded pebbles, and to sustain cultural activities of Neolithic pastoralists. Twenty-two radiocarbon dates bracket 'wet' phases and concurrent prehistoric human occupation from ≈ 8915-8580 ¹⁴C yr BP (9925-9544 cal yr BP) and ≈ 7105-5955 BP (7878-6799 cal yr BP). Increasing amounts of sand were incorporated into the playa after 7500 ¹⁴C yr BP; two optical dates constrain the timing of enhanced aeolian activity from 6720-6250 cal yr. These optical data comprise the only existing absolute ages for the emplacement of aeolian sediments during the rapid transition from wet (playa) to dry (sands) conditions in the Holocene. Playa desiccation after 5955 ¹⁴C yr BP (6799 cal yr BP) was marked by cultural abandonment, evaporite precipitation, dune migration, and deflation. The AMS dates from Umm Akhtar Playa fall in the same range as published radiocarbon data from contemporary sites and playas in Egypt and northern Sudan; the main period of enhanced surface water storage from 8100-6000 BP is linked to the intensified Afro-Asian monsoon forced by cyclical astronomical variations. The record from the Arba'in Desert of Egypt and northern Sudan lags the Northern Hemisphere seasonal insolation maximum (centered at 10,400 BP) and the greatest frequency of African lake highstands, (9500-8500 BP) and may result from biogeophysical feedback mechanisms involved with the 'recycling' of water within the continental interior. Sub-millenial variability apparent in the composite record from Egypt likely reflects the influence of atmospheric-oceanic dynamics throughout the Holocene.
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Orolowitz, Matthew. "Life on the edge: do body size and drinking dependency influence how birds deal with the heat in South Africa's most extreme desert?" Master's thesis, University of Cape Town, 2020. http://hdl.handle.net/11427/32497.
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Climate change-induced increases in air temperature pose a substantial risk to birds inhabiting arid environments. Terrestrial endotherms, such as birds, can respond to high temperatures by moving to cooler microsites, increasing heat dissipation behaviour and/or suppressing activity. Previous studies have suggested that larger bird species may have a greater suppression of activity (e.g. foraging) than smaller species at high air temperatures. However, this body mass effect may be confounded by drinking behaviour, since different species have diverse drinking ecologies. Using four species of lark that inhabit the Tankwa Karoo National Park, I investigated whether foraging activity and other heat-influenced behaviours were influenced by body mass or drinking behaviour when comparisons were constrained within a single family. These lark species were: Red-capped Lark (24 g), Spikedheeled Lark (25 g), Karoo Lark (29 g) and Large-billed Lark (45 g). There was a two-fold difference in body mass between the lightest (Red-capped Lark) and the heaviest (Large-billed Lark). Moreover, two of these lark species drink surface water (drinking larks; Red-capped and Large-billed Lark) and two do not (non-drinking larks; Spike-heeled and Karoo Lark). I also collected data on other passerines present in the Tankwa Karoo for comparison to the larks. Black bulb thermometers were used to measure the thermal landscape and a combination of instantaneous scan samples and focal observations to record bird behaviour. Black bulb temperatures were as much as 8.16 °C cooler in shaded than in sunny locations. Similarly, black bulb temperatures were as much as 8.02 °C cooler off the ground than on the ground. The results from scan sample data showed limited support that foraging was negatively correlated (although non-significant) with mass between lark species as temperatures increased; however, data from focal observations suggested larks that obtain all water from food had a greater reduction in foraging as temperatures increase than larks that drink free surface water. Within scan samples, heat dissipation and shade-seeking behaviour appeared to be more strongly influenced by whether the species drinks free surface water or not than by differences in body mass. Furthermore, drinking larks dissipate heat at lower temperatures and seek shade at higher temperatures than non-drinking larks. Foraging intensity was higher in the sunny microsites as compared to shaded microsites for all species, suggesting that drinking larks might gain an energetic benefit due to increased heat tolerance. Therefore, non-drinking species may be vulnerable to foraging-thermoregulation trade-offs under climate change. However, ongoing drying trends in the Tankwa Karoo and reduced availability of surface water may make drinking species more vulnerable to climate change in the future than non-drinking species.
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Du, Plessis Katherine. "Heat tolerance of Southern Pied Babblers in the Kalahari Desert : how will they respond to climate change?" Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10421.
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An increasing incidence of mass mortalities of birds in hot deserts suggests that birds may be appropriate candidates for assessing how natural selection, under the influence of climate change, drives adaptation. ... The effects of ambient temperature on daily weight gain, foraging effort and efficiency and the presence of heat-dissipation behaviours were assessed to determine the mechanisms by which increased temperature affect babbler body condition.
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Neilson, Julia W., Katy Califf, Cesar Cardona, Audrey Copeland, Treuren Will van, Karen L. Josephson, Rob Knight, et al. "Significant Impacts of Increasing Aridity on the Arid Soil Microbiome." AMER SOC MICROBIOLOGY, 2017. http://hdl.handle.net/10150/625716.
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Global deserts occupy one-third of the Earth's surface and contribute significantly to organic carbon storage, a process at risk in dryland ecosystems that are highly vulnerable to climate-driven ecosystem degradation. The forces controlling desert ecosystem degradation rates are poorly understood, particularly with respect to the relevance of the arid-soil microbiome. Here we document correlations between increasing aridity and soil bacterial and archaeal microbiome composition along arid to hyperarid transects traversing the Atacama Desert, Chile. A meta-analysis reveals that Atacama soil microbiomes exhibit a gradient in composition, are distinct from a broad cross-section of nondesert soils, and yet are similar to three deserts from different continents. Community richness and diversity were significantly positively correlated with soil relative humidity (SoilRH). Phylogenetic composition was strongly correlated with SoilRH, temperature, and electrical conductivity. The strongest and most significant correlations between SoilRH and phylum relative abundance were observed for Acidobacteria, Proteobacteria, Planctomycetes, Verrucomicrobia, and Euryarchaeota (Spearman's rank correlation [r(s)] = >0.81; false-discovery rate [q] = <= 0.005), characterized by 10- to 300-fold decreases in the relative abundance of each taxon. In addition, network analysis revealed a deterioration in the density of significant associations between taxa along the arid to hyperarid gradient, a pattern that may compromise the resilience of hyperarid communities because they lack properties associated with communities that are more integrated. In summary, results suggest that arid-soil microbiome stability is sensitive to aridity as demonstrated by decreased community connectivity associated with the transition from the arid class to the hyperarid class and the significant correlations observed between soilRH and both diversity and the relative abundances of key microbial phyla typically dominant in global soils. IMPORTANCE We identify key environmental and geochemical factors that shape the arid soil microbiome along aridity and vegetation gradients spanning over 300 km of the Atacama Desert, Chile. Decreasing average soil relative humidity and increasing temperature explain significant reductions in the diversity and connectivity of these desert soil microbial communities and lead to significant reductions in the abundance of key taxa typically associated with fertile soils. This finding is important because it suggests that predicted climate change-driven increases in aridity may compromise the capacity of the arid-soil microbiome to sustain necessary nutrient cycling and carbon sequestration functions as well as vegetative cover in desert ecosystems, which comprise one-third of the terrestrial biomes on Earth.
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Martin-Rivera, Martha H. "The Effect of Climate and Spittlebug (aeneolamia albofasciata) on Buffelgrass (cenchrus cilaris L.) Productivity in the Sonoran Desert." DigitalCommons@USU, 1994. https://digitalcommons.usu.edu/etd/4508.
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I conducted field studies during 1984-1988 to determine how (1) precipitation amount and distribution affect buffelgrass [Cenchrus ciliaris L. (Link) l productivity, (2) summer rainfall amount and distribution and temperature influenced the spittlebug (Aeneolamia albofasciata Lalleman) life cycle, and (3) summer burning affects spittlebug densities and buffelgrass productivity.
Experiment I was conducted from 1985 through 1988. Forage samples collected at 15 -day intervals were separated into live, recent-dead standing, old-dead standing, and litter. There was a positive relationship between the summer precipitation and the live biomass. Recent-dead standing and old-dead standing decomposed during the summer, fall, or spring.
Experiment II was conducted during summers of 1984, 1985, and 1986. studied climatic effects on spittlebug life cycle and monitored nymph and adult populations. Egg hatch occurred after accumulative summer precipitation exceeded 50 mm. Five nymphal stages were completed in an average of 27 days and the life cycle averaged 43 days.
Experiment III was conducted during the summer of 1985 and 1986. Four burning treatments were applied at different stages within the spittlebug life cycle. Burning should be conducted as buffelgrass initiates summer growth, and between the second and third nymphal stages. Burns conducted before plant growth and during rapid growth damaged the plant , and insect control was inconsistent.
My studies will help ranchers in northwestern Mexico, south Texas, and northeast Mexico effectively manage buffelgrass pastures. Forage accumulation and decomposition cycles can be used to adjust stocking rates, and knowledge of the insect life cycle and plant productivity can be used to maximize insect control and minimize adverse effect on plant productivity.
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Vine, Michael David. "Between the event and the ordinary : climate crises and the ecologies of everyday life in the California desert." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/274463.
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The notion of an environmental crisis or catastrophe conjures connotations of rupture, emergency, and impermanence: an intermediary moment of chaos in which the normal order of things collapses in on itself only to be brought back to life—or “recovered”—after the crisis is finished. It is by definition an event out of the ordinary, which in turn is idealised as the realm of routine, repetition, and the reproduction of the social order. But how might such crises permeate the body, home, and other ecologies of everyday life? And how might these ecologies be marshalled and transformed in a time of unfolding change? California is currently caught in a cascade of intersecting environmental crises, erupting most spectacularly with the state’s “historic” drought, which lasted from 2011 to 2017 and peaked in 2014/2015. Alongside the drought and its second order ramifications like wild fires and dust storms, the local manifestations of a changing climate are converging to generate among Californians a sense of near-constant crisis that is both powerful and widespread. Based on thirteen months' fieldwork from June 2014 to July 2015 in the arid lands of Central and Southern California, this thesis examines everyday lived experiences of space and time amidst this scene of instability and uncertainty. Each chapter tracks from a different vantage point the ways in which people are experimenting with the material, practical, and symbolic elements of “the ordinary” in response to the discontinuities introduced into daily life by forces beyond their control. It is my assertion that these ongoing and open-ended practices are poorly captured by the concept of “recovery”—a recurrent figure in the anthropology of disaster—which strongly suggests a telos of return to some or another pre-disaster way of life. The central argument of the thesis, then, is that these processes of experimentation must be understood in an analytical framework that embraces rather than disavows the mutual absorption of the ordinary and the event. As such, the thesis examines the improvisational as well as the habitual aspects of everyday life, whilst also directing attention to the generative as well as destructive dimensions of environmental crisis. Sure enough, environmental crises can incite shock and trauma in those that live through them. At their most extreme, they may also reduce life to a state of bare survival. Yet my interlocutors also took great pride in their collective capacities not only to “weather the storm” but also to invent new modes of self-sufficiency in response to their altered physical circumstances. In doing so, they all drew heavily upon images of California’s past in order to make sense of their present and chart paths for future action. As such, the thesis will contribute to anthropologies of disaster, the ordinary, and historical imagination and practice in the contemporary United States.
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Flesch, Aaron D., Philip C. Rosen, and Peter Holm. "Long-term changes in abundances of Sonoran Desert lizards reveal complex responses to climatic variation." Wiley, 2017. http://hdl.handle.net/10150/626024.
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Understanding how climatic variation affects animal populations and communities is essential for addressing threats posed by climate change, especially in systems where impacts are projected to be high. We evaluated abundance dynamics of five common species of diurnal lizards over 25 years in a Sonoran Desert transition zone where precipitation decreased and temperature increased across time, and assessed hypotheses for the influence of climatic flux on spatiotemporal variation in abundances. We repeatedly surveyed lizards in spring and summer of each year at up to 32 sites, and used hierarchical mixture models to estimate detection probabilities, abundances, and population growth rates. Among terrestrial species, abundances of a short-lived, winter-spring breeder increased markedly by an estimated 2375285% across time, while two larger spring-summer breeders with higher thermal preferences declined by up to 64%. Abundances of two arboreal species that occupy shaded and thus sheltered microhabitats fluctuated but did not decline systematically. Abundances of all species increased with precipitation at short lag times (151.5 yrs) likely due to enhanced food availability, but often declined after periods of high precipitation at longer lag times (254 yrs) likely due to predation and other biotic pressures. Although rising maximum daily temperatures (Tmax) are expected to drive global declines of lizards, associations with Tmax were variable and weak for most species. Instead, abundances of all species declined with rising daily minimum temperatures, suggesting degradation of cool refugia imposed widespread metabolic or other costs. Our results suggest climate warming and drying are having major impacts on lizard communities by driving declines of species with traits that augment exposure to abiotic extremes and by modifying species interactions. The complexity of patterns we report indicate that evaluating and responding to the influence of climate change on biodiversity must consider a broad array of ecological processes.
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Janz, Lisa. "Chronology of Post-Glacial Settlement in the Gobi Desert and the Neolithization of Arid Mongolia and China." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/223342.
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Prior to this study, knowledge of Gobi Desert prehistory was mostly limited to early and mid-20th century descriptions of undated stone tool assemblages from unanalyzed museum collections. This research focuses on the use of extensive existing museum collections to establish a baseline chronology of technology, economy, and land-use for prehistoric Gobi Desert groups. Radiocarbon and luminescence dating are used to establish an artefact-based chronology and provide a relative age for 96 archaeological site assemblages. Interpretations of land-use derived from lithic analysis are compared to detailed regional and local palaeoenvironmental records in order to contextualize residential mobility and subsistence. Results indicate that a dramatic shift in land-use after about 8000 years ago was related to a combination of widespread forestation and the increased productivity of lowland habitats during a period of high effective moisture. Hunter-gatherers organized their movements around dune-field/wetland environments, but utilized a range of both high- and low-ranked foods such as large ungulates from adjoining plains and uplands, and seeds and/or tubers from dune-fields and wetlands. New radiocarbon dates indicate that the use of dune-fields and wetlands persisted into the early Bronze Age, overlapping with the rise of nomadic pastoralism across Northeast Asia. These findings illuminate the period just prior to the rise of nomadic pastoralism in Northeast Asia and add considerable depth to our understanding of hunter-gatherer adaptations within arid environments following the Last Glacial Maximum.
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Ritter, Benedikt [Verfasser], Tibor J. [Gutachter] Dunai, Martin [Gutachter] Melles, and Eduardo [Gutachter] Campos. "Landscape and climate evolution in arid to hyperarid climates with special focus on the Atacama Desert / Benedikt Ritter ; Gutachter: Tibor J. Dunai, Martin Melles, Eduardo Campos." Köln : Universitäts- und Stadtbibliothek Köln, 2019. http://d-nb.info/118981143X/34.
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Kleinhesselink, Andrew R. "Direct and Indirect Effects of Climate Change on Plant Populations and Communities in Sagebrush Steppe." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5417.
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Forecasting the effects of climate change on plant and animal populations is a high priority in ecology. We studied the effects of climate on plant populations through the use of observational and experimental data, as well as analytical models. Our research questions were: (1) Do the effects of interannual climate variation on the population growth rates of widespread species show a coherent pattern across gradients of mean annual climate? (2) How well can population models fit to observational data predict the response of populations to field experiments that manipulate climate? And (3) does niche overlap between competitors predict the magnitude of competition-mediated indirect effects in mechanistic resource competition models? To test the first question, we assessed how interannual variation in climate affected the abundance of big sagebrush (Artemisia tridentata) at 131 monitoring sites across its range. We found that years of above average temperature increased sagebrush abundance at cold sites, but decreased sagebrush abundance at hot sites. This pattern indicates that sagebrush distribution may be limited by hot and cold temperatures at the extremes of its distribution. We addressed iv our second research question by fitting statistical models to over 25 years of observational data on the performance of four dominant plant species in a sagebrush steppe community. We then experimentally manipulated soil moisture in this community and tested how well the statistical models fit to observational data could predict species’ responses to the experimental treatments. In two out of four species, we found that including climate effects in our models helped us predict the population-level responses to the experiment. Moreover, effects of historical soil moisture variation on vital rates were generally consistent with the effects of drought and irrigation treatments. Our results provide some evidence that observational data can be used to predict species’ responses to climate change in the future. We addressed our third question by simulating environmental change in analytical models of resource competition and quantifying the size of direct and competition-mediated indirect effects that resulted. We showed that the magnitude of indirect effects increased as the niche overlap between competitors increased.
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Smit, Ben. "Taking the heat : integrating behavioural and physiological variables to predict avian responses to climate change in the Kalahari Desert." Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/79186.
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Holmes, Christopher Dale. "Effects of three global climate change factors on soil water and sap flow of Larrea tridentata in the Mojave Desert." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464439.
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Warren, Daniel Cram. "Transpiration and conductance responses of salt-desert vegetaion in the Owens Valley of California in relation to climate and soil moisture." Diss., The University of Arizona, 1991. http://ezproxy.library.arizona.edu/login?url=.
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O'Connor, Rory Charles. "Small Mammals Matter? Linking Plant Invasion, Biotic Resistance, and Climate Change in Post-Fire Plant Communities." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5756.
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The introduction and establishment of exotic species can profoundly alter ecosystems. Two exotic species drastically changing the landscape of deserts in western North America are Bromus tectorum L. and Bromus rubens L. Through the buildup of biomass and slow decomposition rates in deserts these two exotic annual grasses can alter fire regimes that change the plant and animal community dynamics in the ecosystems. To better understand the ecological mechanisms that could restrict or alter the patterns of invasive plant establishment we established a replicated full factorial experiment in the Great Basin and Mojave Desert. The combinations of factors being manipulated are burned or intact plant communities, and presence or exclusion of small mammals. Generally invasive species establishment is thought to be a result of competitive superiority or lack of natural enemies, but if that is the case then why do not all invasive species establish and become highly abundant in their new ecosystems? To understand why some invasive species establish and others do not we monitored three dominant exotic species from the Great Basin and the Mojave Desert, B. tectorum, Halogeton glomeratus (M. Bieb.) C.A. Mey., and B. rubens. We observed that the presence of small mammals create a biotic resistance to B. tectorum, H. glomeratus, and B. rubens. This pattern was observed in both intact and burned plant communities; however, it was most prevalent in the burned plant communities. The strength of the biotic resistance on these invasive species varied between species and the years sampled. In deserts both plant and small mammal communities are tightly tied to precipitation. We wanted to understand how invasive species establishment is affected by small mammal presence after a fire disturbance, and manipulating total precipitation. Total precipitation was manipulated through three different treatments: 1) drought or 30% reduction of ambient precipitation; 2) ambient precipitation; 3) water addition or an increase of 30% ambient precipitation. We focused on B. rubens establishment in the Mojave Desert as our model organism by monitoring it beneath rain manipulation shelters nested in burned/intact and small mammal presence/absence full factorial plots. What we observed was that again small mammals created a biotic resistance on the density of B. rubens regardless of the burn or precipitation treatments. This biotic resistance also translated into decreasing B. rubens biomass and seed density. Under the drought and ambient precipitation treatments we found that small mammals kept the density and biomass equal but under increased precipitation the efficacy of biotic resistance on B. rubens density and biomass was lessened by the availability of the added water.
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Rizvani, Lejla. "Cooling Oasis." Thesis, KTH, Arkitektur, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298809.
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The urban heat island, UHI, is a phenomenon that occurs in all cities. This phenomenon is an effect of us humans and the environments we have built. What happens in cities are that they re-emit the suns heat and other energies trapping them in this heat island. The re-emitting happens through the pavement of the city, lack of greenery, roads and how the city is built and its geometry. Cities with skycrapers and of high density see a greater impact of the urban heat island where the wind flow is reduced and more heat is trapped and stored. The UHI is worst experienced in places with a very hot climate, such as the arid desert climate with extreme temperatures year round, like in the UAE and Dubai. It is vital to tackle the UHI effect problem, because it puts people at danger. Many lives are shed each year due to heat strokes, that can be reduced if we take this problem into consideration when we design our cities. The UHI effect can be reduced by simple yet effective steps.
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Fitzpatrick, Ginny M. "Thermal Ecology of Mutualism: The Consequences of Temperature for Ant-Plant Interactions." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/321375.
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Mutualism is an often-complex positive interaction between species, each of which responds independently to varying biotic and abiotic conditions. Temperature is an important factor that can affect species both directly (e.g., physiologically) and indirectly (e.g., via its effects on interactions with consumers, competitors, and mutualists). Although much research has investigated the consequences of temperature for individual organisms, the effects of temperature on the formation, dissolution, and success of species interactions remain minimally understood. The unique ways in which species respond to temperature likely play a role in structuring communities. Environmental heterogeneity, including the thermal environment, can promote coexistence when species exploit resources in different ways, such as by occupying different thermal niches. This dissertation examines the consequences of temperature for participants in an ant-plant protection mutualism, and investigates how the thermal ecology of individual species affects the interaction. Many mutualisms involve multiple species, or interacting guilds. In these mutualisms, species interact with partner species that vary in multiple characteristics. Mutualists are quite sensitive to both partner quantity and partner quality (e.g., their effectiveness at performing a beneficial task). Mutualisms between ants and plants are common across a variety of habitats worldwide, which differ in thermal range, fluctuation, and seasonality. In light of ants’ well-studied and predictable responses to temperature, ant-plant interaction networks provide excellent systems for studying the thermal ecology of mutualisms. In ant-plant protection mutualisms, each of the participants (ants, plants, and enemies) likely differs in its response to temperature. In addition to the direct effects of temperature on ant species, temperature may affect the magnitude of mutualistic interactions among species by affecting the quantity and quality of the reward offered to partners, and the activity of the partners themselves and the plant’s enemies (i.e., herbivores). If herbivores are more thermally tolerant than the mutualistic ant defenders, the consequences for plants may well be severe; however, if herbivores are less thermally tolerant than are the ants, the effects of rising temperatures might be mitigated: although less-effective ants might be more frequent in a warmer world, herbivores would be less abundant there. This dissertation describes the thermal ecology of the participants in a mutualism between the cactus Ferocactus wislizeni and four of its common ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the extreme environment of the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plant, and in exchange protect the plants from herbivores, including a common phytophagous cactus bug, Narnia pallidicornis (Hemiptera: Coreidae). Specifically, it investigates how thermal ecology of the individual species affects the interactions among those species. Also, it considers the impact of a tradeoff between behavioral dominance and thermal tolerance among ants.
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Agha, Mirza Mickey. "A LONG-TERM INVESTIGATION OF THE FEDERALLY THREATENED DESERT TORTOISE (GOPHERUS AGASSIZII) AT A WIND ENERGY FACILITY IN SOUTHERN CALIFORNIA." UKnowledge, 2015. http://uknowledge.uky.edu/forestry_etds/21.
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With the recent increase in utility-scale wind energy development and current climate variation in the desert southwest US, researchers have become increasingly concerned with the reaction of wildlife and critical habitat. Understanding the relationships among monitoring efforts, climate, industrial landscapes and wildlife is critical to effective management. Given the need for information available on how these potential stressors affect terrestrial wildlife, my objective was to determine how climate variation, wind energy facilities (WEF) and monitoring efforts by researchers influence behavior and survivorship in a population of the federally threatened desert tortoise (Gopherus agassizii). Data were collected via surveys, motion-sensor camera trapping and radio-telemetry during the span of two decades at a WEF in California. Using capture-mark-recapture survivorship analysis and generalized linear mixed-effects models, I acquired long-term estimates of survivorship, activity, and levels of stress response to researchers and climate. From this study I found that researchers as well as abiotic effects influence the probability of voiding, a possible stress induced behavior in desert tortoises. Additionally, we found that tortoise activity and survival is constrained by winter precipitation and habitat types. Further research is needed on proximate mechanisms of wind turbines (noise and vibration) and their effects on desert tortoise behavior.
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Gueye, Birahim Moussa. "Modélisation des couplages entre les aérosols désertiques et le climat ouest-africain." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066145.
Full textAbstract:
Nous avons introduit, dans cette thèse, une représentation physique du soulèvement des poussières désertiques sur le Sahara, basée sur les travaux de Marticorena and Bergametti (1995) pour le calcul du flux horizontal des poussières et de Alfaro and Gomes (2001) pour le calcul du flux vertical de poussières optimisé par Menut et al.(2005). Pour valider le calcul du soulèvement de poussières dans le modèle LMDZ, nous avons utilisé la version”Chimere-dust” du modèle de chimie-transport Chimere. Les vents horizontaux des réanalyses ERA-I sont également utilisés pour guider le modèle LMDZ. L’ émission dépend de façon très non linéaire des tensions de vent en surface. Des simulations menées avec les versions ”physique standard” LMDZ5A et nouvelle physiqueLMDZ5B du modèle basée sur des développement récents des paramétrisations de la couche limite convective et de la convection nuageuse. Cette dernière version améliore la représentation du cycle diurne du vent par rapport aux réanalyses utilisées pour le guidage. Le cycle diurne du vent dans les observations et dans les simulations LMDZ montre un maximum marqué en fin de matinée. L'impact sur le soulèvement des poussières de la meilleure représentation du cycle diurne dans la « Nouvelle Physique » se traduit par un accroissement des émissions d'un facteur 2 à 3, venant confirmer l'importance des émissions matinales de poussières dans cette région du globe. La version LMDZ5B inclut également une paramétrisation des poches froides ou courant de densité créés sous les orages par ré-évaporation des pluies. Ces courants de densité sont connus pour contribuer largement au soulèvement des poussières au Sahel et au Sahara en période de mousson, au travers de la formation de haboobs.On montre ici comment une prise en compte relativement simple des bourrasques de vents associées aux poches(diagnostiquées dans le modèle au travers de la « Available Lifting Energy ») permet d'augmenter de façon significative le soulèvement de poussières, et de réconcilier le cycle saisonnier des simulations des concentrations de surface de la poussières et des épaisseurs optiques (sensibles elles à la colonne intégrée) avec les observationsWe have introduced in this thesis, a physical representation of the desert dust lifting over the Sahara, based on the work of Marticorena and Bergametti (1995) to calculate the horizontal flow of dust and the calculation of the vertical flux of dust following Alfaro and Gomes (2001) but optimized by Menut et al. (2005). To validate the calculation of dust emission in the LMDZ model, we used the "Chimere-dust" version of the chemistry-transport model Chimere. Horizontal winds from the ERA-I reanalysis are also used for nudging. The dust emission depends very nonlinearly on the surface wind shear. Simulations conducted with the version "physical standard"LMDZ5A and the version "new physic" LMDZ5B of the model LMDZ based on recent developments in the parameterization of convective boundary layer and cloud. This new version improves the representation of the diurnal cycle of wind relative to the reanalysis used for nudging. The diurnal cycle of wind from the observations and simulated by the version LMDZ5B show a maximum at the end of the morning. The impact of the better representation of diurnal cycle of wind on the dust lifting is the increasing emissions by a factor 2 to 3, that confirm the importance of dust emissions in the morning at this region of the globe. The version LMDZ5B also includes a parameterization of “cold pools” or density current resulting from the re-evaporation of rainfall in the base of the clouds. These density currents are known to contribute significantly to the dust lifting in the Sahel and the Sahara monsoon with the formation of “haboobs”. In this work, we show how a relatively simple consideration of density current's associated wind gusts (diagnosed in the model through the “Available Lifting Energy” ) allows to significantly increase dust lifting, and reconcile the simulations of the seasonal cycle of surface concentrations and the Aerosol Optical Thickness (AOT) of dust with observations
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Murad, Waheed [Verfasser], Frank [Akademischer Betreuer] Schlütz, Hermann [Akademischer Betreuer] Behling, and Markus [Akademischer Betreuer] Hauck. "Late Quaternary Vegetation History And Climate Change In The Gobi Desert, South Mongolia / Waheed Murad. Gutachter: Hermann Behling ; Markus Hauck ; Frank Schlütz. Betreuer: Frank Schlütz." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://d-nb.info/1043029214/34.
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Nobel, Park S. "Water Relations and Carbon Dioxide Uptake of Agave deserti - Special Adaptations to Desert Climates." University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/554207.
Full textAbstract:
Agave deserti Engelm., a common agave of the Sonoran Desert, possesses Crassulacean acid metabolism. Thus, the main period for stomatal opening and net CO, uptake is at night, which leads to a high water -use efficiency. Seedling establishment occurs only when enough water -storage capacity can be generated following germination so that the young seedling can withstand the first drought. Agave deserti is only moderately tolerant of low tissue temperatures but extremely tolerant of high tissue temperatures, an important desert adaptation. Its rosette growth habit leads to a relatively uniform distribution of photosynthetically active radiation over the leaves, which contributes to its high productivity for a desert plant.
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Gueye, Birahim Moussa. "Modélisation des couplages entre les aérosols désertiques et le climat ouest-africain." Electronic Thesis or Diss., Paris 6, 2015. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2015PA066145.pdf.
Full textAbstract:
Nous avons introduit, dans cette thèse, une représentation physique du soulèvement des poussières désertiques sur le Sahara, basée sur les travaux de Marticorena and Bergametti (1995) pour le calcul du flux horizontal des poussières et de Alfaro and Gomes (2001) pour le calcul du flux vertical de poussières optimisé par Menut et al.(2005). Pour valider le calcul du soulèvement de poussières dans le modèle LMDZ, nous avons utilisé la version”Chimere-dust” du modèle de chimie-transport Chimere. Les vents horizontaux des réanalyses ERA-I sont également utilisés pour guider le modèle LMDZ. L’ émission dépend de façon très non linéaire des tensions de vent en surface. Des simulations menées avec les versions ”physique standard” LMDZ5A et nouvelle physiqueLMDZ5B du modèle basée sur des développement récents des paramétrisations de la couche limite convective et de la convection nuageuse. Cette dernière version améliore la représentation du cycle diurne du vent par rapport aux réanalyses utilisées pour le guidage. Le cycle diurne du vent dans les observations et dans les simulations LMDZ montre un maximum marqué en fin de matinée. L'impact sur le soulèvement des poussières de la meilleure représentation du cycle diurne dans la « Nouvelle Physique » se traduit par un accroissement des émissions d'un facteur 2 à 3, venant confirmer l'importance des émissions matinales de poussières dans cette région du globe. La version LMDZ5B inclut également une paramétrisation des poches froides ou courant de densité créés sous les orages par ré-évaporation des pluies. Ces courants de densité sont connus pour contribuer largement au soulèvement des poussières au Sahel et au Sahara en période de mousson, au travers de la formation de haboobs.On montre ici comment une prise en compte relativement simple des bourrasques de vents associées aux poches(diagnostiquées dans le modèle au travers de la « Available Lifting Energy ») permet d'augmenter de façon significative le soulèvement de poussières, et de réconcilier le cycle saisonnier des simulations des concentrations de surface de la poussières et des épaisseurs optiques (sensibles elles à la colonne intégrée) avec les observationsWe have introduced in this thesis, a physical representation of the desert dust lifting over the Sahara, based on the work of Marticorena and Bergametti (1995) to calculate the horizontal flow of dust and the calculation of the vertical flux of dust following Alfaro and Gomes (2001) but optimized by Menut et al. (2005). To validate the calculation of dust emission in the LMDZ model, we used the "Chimere-dust" version of the chemistry-transport model Chimere. Horizontal winds from the ERA-I reanalysis are also used for nudging. The dust emission depends very nonlinearly on the surface wind shear. Simulations conducted with the version "physical standard"LMDZ5A and the version "new physic" LMDZ5B of the model LMDZ based on recent developments in the parameterization of convective boundary layer and cloud. This new version improves the representation of the diurnal cycle of wind relative to the reanalysis used for nudging. The diurnal cycle of wind from the observations and simulated by the version LMDZ5B show a maximum at the end of the morning. The impact of the better representation of diurnal cycle of wind on the dust lifting is the increasing emissions by a factor 2 to 3, that confirm the importance of dust emissions in the morning at this region of the globe. The version LMDZ5B also includes a parameterization of “cold pools” or density current resulting from the re-evaporation of rainfall in the base of the clouds. These density currents are known to contribute significantly to the dust lifting in the Sahel and the Sahara monsoon with the formation of “haboobs”. In this work, we show how a relatively simple consideration of density current's associated wind gusts (diagnosed in the model through the “Available Lifting Energy” ) allows to significantly increase dust lifting, and reconcile the simulations of the seasonal cycle of surface concentrations and the Aerosol Optical Thickness (AOT) of dust with observations
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Aronsson, Sofia. "Varm klimatutbildning för blivande officerare." Thesis, Swedish National Defence College, Swedish National Defence College, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-777.
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Försvarsmakten genomför skarpa uppdrag på flera platser i världen, både i extrem kyla och hetta för att lyckas lösa påfrestande uppgifter krävs både kunskap och erfarenhet. Syftet med uppsatsen är att undersöka om Militärhögskolan Karlberg bör utbilda sina kadetter i varmt klimat, så att de innehar kunskapen innan de kommer ut på sina förband. Syftet har brutits ned i följande frågeställningar. Huvudfrågeställning: Bör kadetter på militärhögskolan utbildas i varmt klimat?Delfrågor: Definiera vad varmt klimat är, Hur påverkar värmen människan och vilka risker finns? Vilka utbildningar bedriver Försvarsmakten idag över varmt klimat?Varför utbildar inte Militärhögskolan Karlberg sina kadetter i varmt klimat? Jag har använt mig av metoden induktion vilket innebär att jag gjort empiriska iakttagelser i form av intervjuer samt litteratursökning och sedan dragit slutsatser utifrån dessa. Uppsatsens viktigasteslutsatser är: Utbildning i kallt väder är en god grund, men är inte tillräcklig för att behärska ett varmt klimat. En kompletteringsutbildning för varmt klimat bör eftersträvas på officersprogrammet. Denna utbildning bedrivs på överlevnadsskolan och heter SERE B.
The Swedish Armed Forces have taken part and participated in several countries in the world, both in extreme cold and heat. To succeed in solving challenging tasks requires both knowledge and experience. The purpose of this paper is to find out if the the Military Academy Karlberg should train their cadets in hot weather, so they have the knowledge before they start working within their units. The aim has been divided into the following questions. Main Issue: Should the Military Academy cadets be trained in hot weather? A secondary purpose with the analysis is to answer following issues: Define hot weather? How does heat affect the human body, and what are the risks? What training does the Swedish Armed Forces conduct regarding warm weather today? Why does the Swedish Armed forces not train their cadets in The Military Academy Karlberg on hot weather? I have used the method induction, which means that I have done empirical observations by interviews and through literature search and then drawn conclusions from them.
Essay main conclusions are: Training in cold weather is a good basis, but is not sufficient to master a warm climate. A additional training in hot weather should be sought in the officer program. The training is conducted at the Survival School and is called SERE B
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Lehmann, Philipp Nicolas. "Changing Climates: Deserts, Desiccation, and the Rise of Climate Engineering, 1870-1950." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:13070077.
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This dissertation examines the impact of the nineteenth-century discussions about climate change and desiccation on large engineering projects in desert regions between 1870 and 1950. It demonstrates that the debate over the variability of global climatic conditions was a product of both internal academic and transnational political developments, and that the perceived threat of advancing desert conditions found a popular and technocratic expression in climate engineering designs.
Against the background of new theories about the earth's geological history, the development of academic geography, the travels of Sahara explorers, and imperialism in North Africa, European geographers and geologists initiated an enduring discussion on the origin of desert environments and the question of large-scale climatic changes in the recent past and present. Using a wide array of evidence ranging from cave paintings found in the interior Sahara and classical travel accounts to modern meteorological data, scientists debated whether North Africa, the entire continent, or even the whole world were undergoing desiccation. While the lack of a widely-accepted causal mechanism behind large climatic changes meant that the academic debate remained unresolved by the beginning of the twentieth century, images of progressing desert conditions had already left the confines of academia, heightening public anxiety over the possibility of future climatic catastrophes on a global scale.
From the early stages of the nineteenth-century debate on climate change, fears of desiccation inspired scientists and engineers to come up with solutions to detrimental climatic shifts, whether these were viewed as man-made or natural. The resulting climate engineering projects were an expression of environmental pessimism paired with a powerful technological optimism. This was apparent in French and British schemes in the late nineteenth century that aimed to flood large parts of the Sahara and effect wide-ranging climatic changes; in the plan of a German architect to engineer a geographically and climatically transformed new Euro-African continent in the 1920s; and eventually in Nazi designs to Germanize and green the "desertified" areas of Eastern Europe and Central Asia.History
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Said, Ahmed Hami. "Etude de l’alimentation hydrique du palmier dattier (Phoenix dactylifera L.) dans le contexte pédoclimatique de la zone littorale de la République de Djibouti." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2034/document.
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Le palmier-dattier constitue une des rares cultures à vocation alimentaire adaptées aux conditions climatiques extrêmes (sécheresse, salinité), telles que rencontrées à Djibouti. Dans un contexte de ressources en eau fortement limitées, la connaissance des modalités de l’alimentation hydrique du palmier dattier est essentielle. L’objectif de ce travail de recherche est d’acquérir cette connaissance, dans le contexte pédoclimatique de Djibouti, par la réalisation d’un suivi in situ du fonctionnement hydrique du système sol-palmier, à l’échelle d’un individu, et la quantification du puits racinaire du palmier-dattier. Un palmier-dattier, pleinement développé, a été instrumenté à l’échelle de la cuvette d’irrigation, à l’aide de plusieurs tubes d’accès de sonde à neutrons, pour le suivi de la teneur en eau volumique du sol, et de plusieurs tensiomètres, répartis de 10 à 160 cm de profondeur. Trois expériences d’infiltration/redistribution a été réalisées successivement, la première sans altérer le fonctionnement du système sol-palmier, la seconde après avoir coupé le palmier, tout en permettant l’évaporation de la surface du sol, la dernière après avoir couvert la surface du sol afin d’empêcher l’évaporation. Les résultats mettent en évidence une forte hétérogénéité des propriétés hydriques du sol, avec une stratification liée au contexte sédimentaire littoral. L’impact du puits racinaire sur la dynamique hydrique du sol est observé jusqu’à 80 cm de profondeur. Pour la période fraîche, les besoins en eau du palmier dattier sont estimés à 130 L par jour, avec une fréquence d’irrigation d’une fois toutes les 2 semaines. Pour la première fois, le coefficient cultural du palmier dattier (kc = 1,39) a été établi dans les conditions climatiques de Djibouti. Les résultats obtenus contribueront à une meilleure gestion de l’irrigation et à une meilleure maîtrise du risque de salinisation du sol dans le contexte pédoclimatique de la République de DjiboutiDate palm is one of the few food crops adapted to the extreme weather conditions (drought, salinity), such as encountered in Djibouti. In the context of highly limited water resources, knowledge of the date palm water requirements is essential. The objective of this research was to determine the date palm water requirements, in the Djibouti pedoclimatic context, using in situ monitoring of water transport in the soil-plantatmosphere system, at the scale of a single date palm tree, and to quantify the date palm root water uptake. A fully developed date palm tree was instrumented at the irrigation basin scale, using several access tubes for neutron probe for monitoring the soil volumetric water content, and several tensiometers, installed from 10 to 160 cm depth. Three infiltration/redistribution experiments have been performed successively, the first without alteration of the soil-plant system, the second after cutting off a date palm tree while allowing the surface evaporation, the last with covering the soil surface to avoid evaporation. The results show large heterogeneity in soil hydraulic properties, with stratification linked to the coastline sedimentary context. The root water uptake is observed up to 80 cm depth. The date palm water requirements in the fresh period are estimated at 130 liters per day with a frequency of irrigation of one time every two weeks. For the first time, the date palm cultural coefficient has been established in the Djibouti climatic conditions (kc = 1.39). The obtained results will contribute to better management of irrigation and to improve the control of soil salinization in the pedoclimatic context of the Republic of Djibouti
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Fossati, Jacques. "Caractéristiques du système oued en milieu hyperaride, végétation des oueds du désert oriental septentrional (Egypte) et phytoécologique d'un secteur de l'oued Sannur." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10138.
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La vegetation des oueds est etudiee a deux echelles spatiale: la region du desert oriental septentrional d'egypte (3010'n a 2610'n et 3050'e a 3230'e) et un secteur de l'oued sannur (29104n ; 3128'e). A l'echelle regionale, quatre groupements s'individualisent au sein des gradients climatiques nord/sud (precipitations et temperature moyenne annuelle) et nord-ouest/sud-est (evapotranspiration). Un gradient biogeographique se surimpose a cette description, avec des especes mediterranneennes au nord et des especes soudano-angolanes au sud, le fond commun etant saharo-arabique. A l'echelle d'un secteur de l'oued sannur ou la frequence des crues est estimee a sept ans, les especes perennes s'organisent en cinq groupes. La geomorphologie et la granulometrie de surface expliquent une partie de la structure de la vegetation: les especes sont liees au chenal ou aux rives et terrasses d'une part, a une granulometrie de surface fine ou a des zones plus grossieres d'autre part. Les especes annuelles ephemerophytes constituent une synusie ombrique en relation avec les precipitations hivernales et atteignent un maximum de recouvrement au mois de mars. Leur repartition depend essentiellement de la granulometrie dominee par des particules fines. D'une echelle spatiale a l'autre, le poids des facteurs expliquant la structure de la communaute vegetale peut etre different. A l'emboitement des echelles spatiales peut correspondre un emboitement des facteurs mesologiques explicatifs, parmi eux, certains seront pertinents a une echelle donnee et d'autres a plusieurs niveaux
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del, Río Camilo [Verfasser], and Alexander [Akademischer Betreuer] Siegmund. "Spatiotemporal characteristics of coastal fog in the Atacama Desert. A remote sensing based analysis of the past, present and future distribution and variability of low clouds under climate change in a hyper-arid region of northern Chile / Camilo del Río ; Betreuer: Alexander Siegmund." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1206187913/34.
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Sambuco, Emily Nicole. "Exploring Great Basin National Park using a high-resolution Embedded Sensor Network." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555579768450066.
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Unland, Helene Emmi Karin. "Surface flux measurement and modeling at a semi-arid Sonoran Desert site." Thesis, The University of Arizona, 1996. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0257_sip1_w.pdf&type=application/pdf.
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Rizk, Samuel, and Johanna Wickström. "Desertopia." Thesis, KTH, Arkitektur, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122855.
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Today over 80 million Egyptians and the majority of the country’s agricultural land are squeezed into an area the size of Stockholm county. This doesn’t have to be the case since Egypt also has an area about twice the size of Sweden covered by unutilized desert land. We have investigated how Egypt could use the endless resources of the sun and the sea water to colonize its own desert and give its citizens a chance to build a better future. Desertopia covers eight different scales, from the global (1:15 000 000) to the building construction (1:25) and uses architecture and urban design to deal with the issues of climate change, desertification, poverty and unemployment. Desertopia combines traditional vernacular building techniques with the latest climate technology to create a structure that can be used by common Egyptians to take charge of their own future.Idag är över 80 miljoner egyptier och majoriteten av landets jordbruksmark ihopklämda på en yta motsvarande Stockholms län. Det skulle dock inte behöva vara så eftersom Egyptens landyta är dubbelt så stor som hela Sverige. En yta som dock är täckt av öken. Vi har undersökt hur Egypten skulle kunna använda de ändlösa resurserna solen och havsvattnet för att kolonisera sin egen öken och ge sina invånare chansen att bygga sig en bättre framtid. Desertopia täcker åtta olika skalor, från den globala (1:15 000 000) till den enskilda byggnadens konstruktion (1:25) och använder arkitektur och stadsbyggnad för att hantera klimatförändringen, ökenspridningen, fattigdomen och arbetslösheten. Desertopia kombinerar ökenklimatets traditionella byggnadstekniker med den senaste klimatteknologin för att skapa en struktur som kan användas av vanliga egyptier för att ta makten över sin egen framtid.
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Claquin, Tanguy. "Modélisation de la minéralogie et du forçage radiatif des poussières désertiques." Paris 6, 1999. http://www.theses.fr/1999PA066597.
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Rabanal-Arabach, Jorge [Verfasser]. "Development of a c-Si Photovoltaic Module for Desert Climates / Jorge Rabanal-Arabach." Konstanz : KOPS Universität Konstanz, 2019. http://d-nb.info/1187137391/34.
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