Dissertations / Theses on the topic 'Arctiin'

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1999.
Includes bibliographical references (p. 67-[69]).
Currently available housing in the Arctic is limited to solutions that have been adapted from designs for less severe climates. This thesis has developed a new manner of residential construction designed specifically for the Arctic climate and culture. The system invented ensures a variety of building options for traditional cultural requirements, while also improving on the level of amenity expected of contemporary dwellings. It has developed a sustainable and responsible building system that represents definite and quantifiable improvements through the use of appropriate technologies.
by Joel A. Turkel.
M.Arch.

CHDS State/Local
Approved for public release; distribution is unlimited
The Arctic environment is in a state of flux and the U.S. government must be prepared to handle the evolution and capitalize on the opportunities. Once barren and desolate, the Arctic is slowly coming to life with industry and commerce brought about by receding ice conditions. Along with that comes the need for a comprehensive and actionable Arctic policy. The other Arctic nations that ring the North Pole are quickly adapting to the shifting Arctic. Unlike the U.S., they have established Arctic policies, are implementing plans to operate in the region, and taking advantage of the opportunities that this new frontier has to offer. The U.S. framework is the National Strategy for the Arctic Region. The plan is short on detail and aspirational in nature. It lacks clear direction and authority. The U.S. has yet to commit to its role as an Arctic nation. The U.S. Arctic lacks infrastructure such as a deep-water port, a joint military base, and additional heavy icebreaker assets. Additionally, there is no lead agency that has authority and funding to carry out U.S. Arctic objectives. Under the current state of affairs, the U.S. is vulnerable to security, economic, and sovereignty issues in the Arctic.

With the recent increase of interest in Arctic, the need rises for new tools for understanding the typical mechanisms of this very unique and so vulnerable area. The coast, which concentrates nearly all of the human activities, is in the front line and probably the most critical part of the system. Trough the past decades, mappings of the Arctic’s shorelines point out huge erosion rates and show the threat of a climate change upon the coast. Recent studies seem to link those tremendous moves to the annual thermal variations within the soil. However, the mechanisms of thermal abrasion that are suggested to be at the hearth of the process are not yet completely understood.In answer for the need of numerical models for thermal analysis of the erosion process, this thesis proposes a toolbox specially designed, based on literature review and fieldwork data. Trough the chapters, the reader shall find essential tools for estimations of the heat transfer into a soil and complete understanding of the physical mechanisms behind. Critical parameters that influence the erosion process are highlighted. To assess the operational deployment of those tools, a thermal analysis of a site has been performed. The conclusions demonstrate the capacity of numerical models to underline the critical gears of the heat transfers, and hopefully will help understanding the erosion processes of this particular place.

Lilliputian Arctic Deviation is a work for small orchestra inspired by average snow and ice extent in the Northern Hemisphere over four decades. Something so large as forty years of snow and ice coverage can be interpreted as what Timothy Morton calls a hyperobject, an entity so vast in space and time that we as human beings cannot experience it within our limited senses and lifespans. For example, we can’t experience 150 years of global warming directly, but we can conceptualize it as an idea, or observe it as a graph. Like a graph, Lilliputian Arctic Deviation is an attempt to experience a hyperobject, while also allowing the composer free rein to creatively interpret and comment on the hyperobject. The Rutgers University Global Snow Lab records weekly and monthly snow extent averages for the Northern Hemisphere from 1967 until the present day. Lilliputian Arctic Deviation focuses on the summer yearly averages. Certain characteristics of the data, when graphed, show patterns that have both scientific and, after translation through algorithmic processes, musical significance. These characteristics are: 1. A significant decline in average snow extent from 1967 to the present; and 2. A transition from drastic yearly differences in the late 1960s through early 1990s to more consistent and predictable values in the late 1990s to 2015. Lilliputian Arctic Deviation proceeds in chronological order, starting with 1967 and ending with 2015. The density of the musical texture reflects the shape of the graph. Higher yearly averages involve more instruments sounding simultaneously, and lower yearly averages involve fewer instruments. Similar yearly average data values are reflected through shared musical materials; the range under which data points are located have similar characteristics. I group the data into eight regions: 3–3.9, 4–4.9,…10–10.9. Data points falling within a similar region share motivic, melodic, harmonic, and timbral materials. Other musical aspects of the piece reflect summer’s place within the larger hyperobject that includes all four seasons. The general characteristics of fall, winter, and spring are implied through listening to the summer, Lilliputian Arctic Deviation. Generally, Lilliputian Arctic Deviation features sharp articulated sounds of short duration, while sustained pitches are dynamically soft and fade in and out of the overall texture. Certain timbres are tight and subdued, such as a prevalence of muted brass, pizzicato and col legno battuto in the strings, and the use of wooden percussion. Set class (014) is used exclusively throughout the piece and is reflective of the small amount of snow and ice in the Northern Hemisphere respective to the amount found in the winter. Finally, since this process of the Earth has been and will continue to happen long before and after the years featured in this piece, this musical composition serves as an interpretation of a small fraction of the overall process, a hyperobject well beyond our ability to experience in our lifetimes.

Today, more people have the opportunity to travel which means that more places need to raise awareness that they exist. In the global world that we live in today, competition among places are growing. This means that places need to work on their marketing to create a unique and special image that reaches out through all the noise. This study aims to investigate why a special image is chosen, in this case why the destination Swedish Lapland have chosen to market a region in north of Sweden as an artic destination. The study also aims to investigate what is included in the concept of an artic destination and what is comprehended in an artic lifestyle, which also is a theme that is used in the marketing of the region. Are there any challenges by using the artic and artic lifestyle concept in the marketing and what consequences can it entail? To answer these questions interviews where made with informants that have a professional work connection to the area. The result showed that the arctic region is complex phenomena to define also for those who use the expression in marketing. What is included in the artic concept and the lifestyle is connected to a lot of conceptions of the nature, culture, climate and experiences. The informants gave different viewpoints about challenges when marketing a large region and the consequences that can be registered. The hope with this study was to get a deeper understanding about the area and especially why a specific theme as the artic was used in marketing purpose for a region in north of Sweden.

This is a master thesis by Maria Ader and David Axelsson, students at the Master of Science in Engineering degree program in Design and Product Realization at KTH, within the master program Integrated Product Design. The thesis work will benefit ÅF and the EU project ɪɴᴛᴇʀᴀᴄᴛ. The ɪɴᴛᴇʀᴀᴄᴛ project is part of the EU’s effort to forward climate research, and aims to “coordinate and harmonize research and monitoring efforts that will greatly contribute to our knowledge and understanding of changes occurring in the arctic environment.” One out of 12 subprojects within ɪɴᴛᴇʀᴀᴄᴛ aims to “increase awareness of drone technology and sensors among researchers and research station managers while making industry aware of innovative potential uses requiring drone and sensor development.” A drone is an unmanned aerial system/vehicle (UAS/UAV), i.e. an airborne vehicle without a human pilot aboard. This master thesis examines the need of drones at the ɪɴᴛᴇʀᴀᴄᴛ research stations and how arctic climates affect drone technology and the ergonomics of piloting a drone. The thesis also provides an overview of the current state of the drone market and the laws and regulations that affect the use of drones. A survey was distributed within ɪɴᴛᴇʀᴀᴄᴛ to map the researchers’ need of, and attitudes towards, drones, followed by exhaustive interviews with researchers and other key figures. Field testing at Tarfala Research Station provided complementing data. The primary insight from the study was that the researchers’ need, as well as the tasks and methods that they employ, vary greatly. Another insight was that many researchers want to use drones primarily as a sensor platform to collect data from large areas in a short time span. A situation-based drone recommendation and a concept proposal for a simple water sampling solution were made based on the results of the study
Detta är ett examensarbete utfört av Maria Ader och David Axelsson, studenter på civilingenjörsprogrammet Design och Produktframtagning på KTH, med masterinriktning Teknisk Design. Arbetet är utfört åt ÅF i syfte att bidra till EU-projektet ɪɴᴛᴇʀᴀᴄᴛ. Iɴᴛᴇʀᴀᴄᴛ är EU:s satsning på klimatforskning i Arktis och syftar till att “koordinera och harmonisera forskning och miljöbevakning som bidrar till vår kunskap och förståelse av förändringar som sker i de arktiska miljöerna.” Ett av tolv delprojekt inom ɪɴᴛᴇʀᴀᴄᴛ-projektet syftar till att öka medvetenheten om drönarteknologi och sensorer bland forskare och föreståndare på forskningsstationerna inom ɪɴᴛᴇʀᴀᴄᴛ, samt att göra drönarindustrin medveten om nya potentiella användningsområden. En drönare är ett obemannat luftfartyg, d.v.s. en flygfarkost utan pilot ombord. Drönare benämns ibland som “UAS” och “UAV”. I den här rapporten används främst den engelska termen “drones”. Detta examensarbete undersöker behovet av drönare på de forskningsstationer som är delaktiga i ɪɴᴛᴇʀᴀᴄᴛ och hur det arktiska klimatet påverkar drönartekniken och ergonomin. Arbetet kartlägger även drönarmarknaden och de lagar och regler som påverkar användandet av drönare. En utförlig studie genomfördes, där forskarnas behov av drönare undersöktes. En enkät skickades ut inom ɪɴᴛᴇʀᴀᴄᴛ och utförliga intervjuer genomfördes med forskare och andra nyckelpersoner. Ett studiebesök på Tarfala forskningsstation kompletterade med fältdata. Den främsta insikten från studien var att behov, arbetsuppgifter och metoder varierar mycket mellan de olika forskarna. En annan insikt var att många ville använda drönare som sensorbärare, och på så sätt insamla data från stora områden på kort tid. Resultatet från studien låg till grund för en situationsbaserad drönarrekommendation samt ett konceptförslag för en enkel vattenprovtagningslösning.

This thesis asks whether there existed a unified view of the Arctic during the time period connected to the high point of British endeavour to find a Northwest Passage, from the first expeditions of the nineteenth-century in 1818 to the return of the last Franklin search party in 1859, forty-one years later. Using this time frame as its marker, the focus of the thesis is primarily on British representations of Arctic landscapes, exploration and Inuit peoples. Through careful empirical analysis of a variety of media, including professional painting, on-the-spot sketches, prints and popular exhibitions, it examines from an art historical viewpoint the historical, political, social and aesthetic contexts in which Arctic representations occurred.

Viruses are the most abundant, ubiquitous and diverse biological entities in the world’s oceans. Through infection and lysis, viruses play critical roles in shaping marine microbial assemblages, with consequences for ecosystem functioning and biogeochemical processes. Despite their global-scale importance in oceanic processes, relatively little is currently known about the distribution, ecological roles and diversity of marine viruses. Furthermore, this existing knowledge is largely limited to temperate and lower latitude ecosystems, leaving the role of viruses in polar waters relatively unexplored. The Canadian Arctic Shelf (CAS) is a heterogeneous and productive marine ecosystem within the Arctic Ocean that plays a key role in carbon cycling. Emerging data suggest that the microbial assemblages on the CAS are active and diverse and can respond rapidly to changes in environmental conditions. This dissertation addresses a knowledge gap regarding marine viruses in polar waters by examining ecology and diversity of marine viruses on the CAS. Toward this end, multiple approaches such as flow cytometry and epifluorescence microscopy, experimental incubations and filtration, molecular techniques (polymerase chain reaction, denaturing gradient gel electrophoresis fingerprint analysis, cloning and sequencing) and statistical analyses were used to investigate 1) spatio-temporal variations in viral distribution and abundance, 2) significance of lysogenic and lytic viral infections and their impacts on host mortality and carbon cycling, 3) patterns in the genetic structure of T4-like viruses (Myoviridae) and phycodnaviruses (Phycodnaviridae), two virus families infecting bacteria and eukaryotic phytoplankton, respectively and 4) phylogenetic diversity and richness of T4-like viruses and phycodnaviruses. Together, the results of these studies have demonstrated that viruses are abundant, active and diverse components of the CAS microbial assemblages, and are strongly coupled with environmental conditions and microbial abundance, productivity and composition. In addition, these studies indicate that viruses are significant agents of microbial mortality on the CAS, and can influence energy fluxes and carbon cycling. Overall, this dissertation has increased our understanding of the marine viruses in arctic environments. Moreover, the results stress the need to include viruses in models when studying the influence of climate changes on biogeochemical cycles in the Arctic Ocean.

Au cours de ces dernières décennies, le climat Arctique a subit de profondes modifications. A l'aide d'une base de données regroupant plus de 18000 observations collectées depuis 1997, nous nous sommes intéressés à la variabilité interannuelle de la partie supérieure de l'Océan Arctique. Les eaux Pacifiques estivales se sont réchauffées depuis la fin des années 1990. En particulier, un flux particulièrement chaud entré en Arctique fin 2004 a pu être documenté tout au long de sa propagation dans le bassin Canadien. Ces analyses suggèrent une possible influence de ces eaux de sub-surface sur l'évolution de la glace de mer dans cette région de l'Arctique. En profondeur, les observations confirment la propagation de plusieurs bouffées d'eaux chaudes d'origine Atlantique, en particulier une anomalie chaude de l'ordre de 0. 8°C détectée pour la première fois en 2004 à l'Ouest du Svalbard. Cependant, nous n'avons pas identifié de tendance au réchauffement graduel de cette eau. Le processus de double diffusion semble être un phénomène assez répandu dans l'ensemble du bassin profond Arctique. Les flux de chaleur verticaux transmis aux interfaces entre deux couches de mélange ont augmenté en raison de l'apparition de super-steps caractérisées par de fortes augmentations en température à l'interface. La halocline est restée relativement stable au cours de la dernière décennie. Sa stratification s'est intensifiée en 2007-2008 dans le bassin Canadien en raison d'une augmentation du contenu en eau douce liée au forçage atmosphérique. Les eaux chaudes Atlantiques sont donc restées isolées de la surface et n'ont pas contribué aux bouleversements observés en surface pendant cette période
The Arctic climate underwent strong modifications over the past decades. Thanks to a data base gathering more than 18000 observations collected in the entire deep basin of the Arctic Ocean since 1997, we focused on the interannual variability of the upper ocean. The subsurface Summer Pacific Water warmed up since the late 1990s. Notably, a particularly warm flux entered the Arctic Ocean in 2004 was documented all along its propagation in the Canadian basin. These analyses suggest a possible influence of the subsurface waters on the sea ice evolution in the Arctic region. At depth, observations confirm the propagation of warm Atlantic water pulses, in particular a warm anomaly of 0. 8°C detected for the first time in 2004 West of Svalbard. Nevertheless, we did not find evidence for any gradual warming trend of this water mass. The double diffusion process seems to be a widespread phenomenon in the entire deep basin. The vertical heat fluxes transmitted through the interfaces between two mixed layers increased since the 1980s, notably because of the “supersteps” appearance, characterized by a strong temperature increase at the interface. Above the thermocline, the halocline remained relatively robust over the past decade. Its stratification intensified in 2007-2008 in the Canadian basin due to a freshwater content increase probably in response to the atmospheric forcing. As a consequence, the warm Atlantic waters remained insulated from the surface waters and did not contribute to the changes observed at the surface over this period

Thesis (M.S. in Applied Science (Physical Oceanography))--Naval Postgraduate School, Sept. 2004.
Thesis Advisor(s): Wieslaw Maslowski. Includes bibliographical references (p. 87-90). Also available online.

The thesis describes fieldwork conducted during the Joint Services Expeditions to Ellesmere Island 1988, 1991 and subsequent modelling activities. Four landlocked populations of Arctic charr, Salvelinus alpinus L., were surveyed at 81 oN, close to the northerly extreme of the species range. They were single-species populations consisting of two distinct size modes, "Dwarf" and "Normal" charr, but with major differences both in size and relative numbers between the lakes. Tentative correlations between population structure, growth rate variation and possible genetic divergence are suggested by this fieldwork and the models examine their credibility. The key hypothesis is that the alternative life history strategies represented by Dwarf and Normal charr represent different solutions to the problem of energy limitation within a size-structured population. Major findings of the models are that alternative life history strategies should be expected to be optimised at different growth rates; density dependence implies that Dwarfs and Normals have equal fitness; a high average juvenile growth rate is likely to lead to a large number of Normals relative to Dwarfs; and that maximum individual fitness is probably achieved in bimodal populations within a "semi-speciated" condition. A combination of evidence further suggests that cannibalism is a likely mechanism for maintenance of the bimodal population structures; and the form of a reaction norm for choice of life history strategy is predicted and found to be similar to one experimentally determined for smolting in Atlantic salmon, Safmo safar L.

The purpose of the thesis is to examine future international relations in the Arctic as a theoretical exercise based on realism and liberalism. As the ice cap shrinks, and the region's environment changes, developing costs will decrease allowing for resource-extraction while new transit routes emerge. The opportunities to develop resources and ship via the Arctic are economic and strategically valuable, altering the geopolitics of the region. This thesis seeks to explore how resource development and new transit routes will affect regional politics through the lens of two theories. The two theoretical approaches will examine states and actors' interests and possible actions. Concluding, that realism will best describe the Arctic as states strive to be the regional hegemon by controlling transit routes and resources or defending the regional status quo, creating tension and a security competition between the U.S., China, and Russia. States will jockey for position within institutions before the ice cap disappears and transit routes emerge. These states seek to grow regional governance in their favor, providing support for a liberal framework, and possibly creating a structure strong enough to reduce tension before states strive to be the Arctic hegemon.

Identifying the drivers of Arctic climate variability is essential for understanding the recent rapid changes in local climate and determining the mechanisms that cause them. Remote tropical sea surface temperatures (SST) have been identified in previous studies as having contributed to the recent positive trends in surface temperature and geopotential height at 200 hPa over north Canada and Greenland (1979-2012) through poleward propagating Rossby waves. However, the source and direction of wave propagation on to north Canada and Greenland (NCG) differs across climate datasets indicating that there are still uncertainties surrounding the mechanisms for how the tropics influence the NCG climate. This thesis aims to further investigate the robustness of the trends over NCG and understand how circulation in this region responds to imposed tropical SST perturbations. The eddy 200 hPa geopotential height (Z200) trends over NCG are assessed in a number of different datasets and compared to the response of eddy Z200 over NCG to imposed tropical SST perturbations in a number of sensitivity studies using the HadGEM3 atmosphere-only model. These model experiments are forced with observed differences in SSTs from the beginning and end of the satellite record (1979-1988 and 2003-2012), with spatial perturbations for [i] the entire tropics, [ii] global SSTs, [iii] the tropical Pacific only, [iv] the tropical Atlantic SST only, [v] the tropical Indian Ocean only. The positive spatial trends of eddy Z200 over NCG from ERA-Interim reanalysis is largely captured in ensemble means of two available climate datasets, UPSCALE and AMIP, indicating that this is a robust climate pattern, however, these trends appear to be stronger in the latter part of the record specifically over the UPSCALE period (1985 to 2011). The model sensitivity studies show that a negative eddy Z200 anomaly over NCG was found in response to all imposed tropical SST perturbations (2003-2012) relative to a background state (1979-1988). This was due a stationary trough over the region that was able to intensify in response to a lack of a strong anomalous wave forcing from changes in mid-tropospheric temperature and zonal winds. The forcing from the tropical Atlantic, relative to the other tropical ocean basins, resulted in the largest eddy Z200 response over NCG, indicating its dominance in forcing the large scale tropical signal. The influence of extratropical SST perturbations relative to tropical SST perturbations were also investigated and it was demonstrated that this negative anomaly is largely driven by the change in tropical sea surface temperatures.

This thesis addresses the consequences of the last glaciation on the distribution and genetic diversity of arctic flora. The principal aim is to infer the full-glacial and postglacial migrational history of Dryas integrifolia M. Vahl. (Rosaceae) from the intraspecific phylogeny of cpDNA haplotypes along with pollen and macrofossil distribution data. The results suggest that four refugia existed during the last glaciation and that each served as significant sources of recolonization when the ice retreated. The two most important refugia are located in the northwestern Arctic (Beringia and the High Arctic), with two other refugia located southeast of the ice sheet and along the coastal regions of the eastern Arctic. High genetic substructure among populations is likely attributable to past vicariance and recent recolonization events, whereas high local diversity is probably indicative of recolonization from several sources and high gene flow in recent time.

Primary production was studied in Fram Sound, part of the Hell Gate-Cardigan Strait polynya, from June to August, 1982. Primary production rates, phytoplankton biomass (chlorophyll α), and water transparency were measured and used in conjunction with modelled solar radiation values to numerically model primary production during this time. The major phytoplankton nutrients were also measured. Early season chlorophyll α concentrations were low, and the increased light availability due to reduced ice cover in this area did not appear to enhance early season production. Chlorophyll concentrations peaked twice; the first peak occured on 20 July and the second on 14 August. The mean primary production rate and phytoplankton biomass were 998 mg C.m⁻² .d⁻¹ and 72 mg chl.m⁻² . This production rate is higher than that measured in other High Arctic areas. Nitrogen, phosphorus and silica were essentially homogeneously distributed during the sampling period and these concentrations varied little from June to August except during 5 days in late August, when they decreased by half then returned to previous levels.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

The seasonal cycle of snow and sea ice is a fundamental feature of the Arctic climate system. In the Northern Hemisphere, about 55 million km2 of sea ice and snow undergo complete melt and freeze processes every year. Because snow and sea ice are much brighter (higher albedo) than the underlying surface, their presence reduces absorption of incoming solar energy at high latitudes. Therefore, changes of the sea-ice and snow cover have a large impact on the Arctic climate and possibly at lower latitudes. One of the most important determining factors of the seasonal snow and sea-ice cover is the timing of the seasonal melt-freeze transitions. Hence, in order to better understand Arctic climate variability, it is key to continuously monitor these transitions. This thesis presents an algorithm for obtaining melt-freeze transitions using scatterometers over both the land and sea-ice domains. These satellite-borne instruments emit radiation at microwave wavelengths and measure the returned signal. Several scatterometers are employed: QuikSCAT (1999–2009), ASCAT (2009–present), and OSCAT (2009–present). QuikSCAT and OSCAT operate at Ku-band (λ=2.2 cm) and ASCAT at C-band (λ=5.7 cm), resulting in slightly different surface interactions. This thesis discusses these dissimilarities over the Arctic sea-ice domain, and juxtaposes the time series of seasonal melt-freeze transitions from the three scatterometers and compares them with other, independent datasets. The interactions of snow and sea ice with other components of the Arctic climate system are complex. Models are commonly employed to disentangle these interactions. But this hinges upon robust and well-formulated models, reached by perpetual testing against observations. This thesis also presents an evaluation of how well eleven state-of-the-art global climate models reproduce the Arctic sea-ice cover and the summer length—given by the melt-freeze transitions—using surface observations of air temperature.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: In press. Paper 4: Submitted.

The purpose of the present study was to establish the prevalence of sensory, neurological and systemic impairments in the Inuit pediatric population (0-18 years) in 13 communities of the Baffin region of the Northwest Territories, Canada.
A data collection instrument (DCI) was developed to obtain clinical data from medical files in each of the Community Health Centres. Impairments rather than disabilities were described and possible causal factors were identified. Data collection took place during the month of June, 1989.
Nearly 13% of Inuit children living in the Baffin area have impairments. Of this group, 15.9% have multiple impairments. The prevalence of children with sensory impairments is 49.4/1000, with neurological impairments is 28.7/1000, with systemic impairments is 30.2/1000 and with multiple impairments is 20.5/1000 children. Over 50% of the impairments reported were due to infectious diseases such as meningitis and chronic otitis media.
The results of this study provide a basis for the development of community based programs which emphasize prevention of impairments in children.
Recommendations for the development of appropriate rehabilitation programs are discussed in the context of the policies of the Canadian government pertaining to the needs of Aboriginal persons with disabilities.

The focus of this thesis is the design of Android applications from building blocks in Arctis. The Arctis tool is used for modeling applications with UML activities, which already can be deployed on the Java ME and Java SE platforms. State machines and a runtime support system are generated. Creation of a generator for Arctis, enabling deployment to the Android platform, is the key element in this work. The Android platform is presented using an example application. A discussion on challenges, solutions and architectures for the design and implementation of Android applications using Arctis is presented. Then, the example application is redesigned using Arctis building blocks and deployed as a Java project using the existing code generator for Java SE. The adaptations necessary for turning the Java project into a runnable Android project is studied in detail and serves as a basis for the development of our code generator, along with the discussion. After describing our code generator, several building blocks are designed for an Android building block library. Demonstration of the code generator and the building blocks are done by designing and deploying an Android application named emph{TwitterFromAndroid}.

The Arctic region attracts considerable scientific interest in these years. Some of the Earth's most pronounced signs of the recent climate change are found here. The summer sea-ice cover is shrinking at an alarming rate. At the same time the region warms faster than the rest of the globe.

The sea-ice reduction implies an increase of solar-radiation absorption at the surface leading to warming which is expected to be larger at higher than at lower latitudes. It is therefore often assumed that the sea-ice reduction is a major cause of the observed Arctic temperature amplification. However, results presented in this thesis suggest that the snow and ice-albedo feedbacks are a contributing but not dominating mechanism behind the Arctic amplification. A coupled climate-model experiment with a doubling of the atmospheric CO2 concentration reveals a considerable Arctic surface-air-temperature amplification in a world without surface-albedo feedback. The amplification is only 8 % larger when this feedback is included. Instead the greenhouse effect associated with an increase of humidity and cloud cover over the Arctic seems to play a major role for the amplification.

Reanalysis data, which are partly based on observations, show Arctic temperature amplification well above the surface in the troposphere. In the summer season, the amplification has its maximum at ~ 2 km height. These trends cannot be explained by the snow- and ice-albedo feedbacks which are expected to induce the largest amplification near the surface. Instead, a considerable part of the trends aloft can be linked to an increase of the atmospheric energy transport into the Arctic.

A major topic of this thesis is the linkage between the mid-latitude circulation and the Arctic warming. It is suggested that the atmospheric meridional energy transport is an efficient indicator of this linkage.

Clouds regulate the Earth’s radiation budget, both by reflecting part of the incoming sunlight leading to cooling and by absorbing and emitting infrared radiation which tends to have a warming effect. Globally averaged, at the top of the atmosphere the cloud radiative effect is to cool the climate, while at the Arctic surface, clouds are thought to be warming. Here we compare a passive instrument, the AVHRR-based retrieval from CM-SAF, with recently launched active instruments onboard CloudSat and CALIPSO and the widely used ERA-Interim reanalysis. We find that in particular in winter months the three data sets differ significantly. While passive satellite instruments have serious difficulties, detecting only half the cloudiness of the modeled clouds in the reanalysis, the active instruments are in between. In summer, the two satellite products agree having monthly means of 70–80 percent, but the reanalysis are approximately ten percent higher. The monthly mean long- and shortwave components of the surface cloud radiative effect obtained from the ERAInterim reanalysis are about twice that calculated on the basis of CloudSat’s radar-only retrievals, while ground based measurements from SHEBA are in between. We discuss these differences in terms of instrument-, retrieval- and reanalysis characteristics, which differ substantially between the analyzed datasets.

Rapid climate change in Arctic regions is of concern due to important feedbacks between the Arctic land surface and the global climate system. A large amount of organic carbon (C) is currently stored in Arctic soils; if decomposition is stimulated under warmer conditions additional release of CO2 could result in an accelerating feedback on global climate. The strength and direction of Arctic C cycle - climate feedbacks will depend on the growth response of vegetation; if plant growth increases some or all of the extra CO2 emissions may be offset. Currently the Arctic is thought to be a small net sink for CO2, the expected balance of terrestrial C sinks and sources in the future is unknown. In this thesis I explore some of the critical unknowns in current understanding of C cycle dynamics in Arctic vegetation. Quantifying gross primary productivity (GPP) over regional scales is complicated by large spatial heterogeneity in plant functional type (PFT) in Arctic vegetation. I use data from five Arctic sites to test the generality of a relationship between leaf area index (LAI) and canopy total foliar nitrogen (TFN). LAI and TFN are key drivers of GPP and are tightly constrained across PFTs in Low Arctic Alaska and Sweden, therefore greatly simplifying the task of up-scaling. I use data from Greenland, Barrow and Svalbard to asses the generality of the LAI-TFN relationship in predicting GPP at higher Arctic latitudes. Arctic ecosystems are unique among biomes in the large relative contribution of bryophytes (mosses, liverworts and hornworts) to plant biomass. The contribution of bryophytes to ecosystem function has been relatively understudied and they are poorly represented in terrestrial C models. I use ground based measurements in Northern Sweden to fill an existing data gap by quantifying CO2 fluxes from bryophytes patches in early spring and summer, and develop a simple model of bryophyte GPP. Using the model I compare bryophyte GPP to that of vascular plants before, during and after the summer growing season, finding that productive bryophyte patches can contribute up to 90 % of modelled annual GPP for typical vascular plant communities at the same site, and that the relative magnitude of bryophyte GPP is greatest in spring whilst the vascular plant canopy is still developing. Understanding how GPP relates to plant growth is important in relating remotely sensed increases in Arctic ‘greenness’ to changes in plant C stocks. I use a 13C pulselabelling techniques to follow the fate of recently fixed C in mixed vascular and bryophyte vegetation, with a focus on quantifying the contribution of bryophytes to ecosystem carbon use efficiency (CUE). I show that bryophytes contribute significantly to GPP in mixed vegetation, and act to increase ecosystem CUE. I highlight the importance of including bryophytes, which do not have roots, in aboveground: belowground partitioning schemes in C models. To further explore C turnover in bryophytes, I use the results of a second 13C labelling experiment to develop a model of C turnover in two contrasting Arctic mosses (Polytrichum piliferum and Sphagnum fuscum). I find significant differences in C turnover between Polytrichum piliferum which respires or translocates about 80 % of GPP, while Sphagnum fuscum respires 60 %. This analysis is the first to explicitly model differences in C partitioning between Arctic bryophyte species. Finally, I discuss the implications of each chapter for our understanding of Arctic C dynamics, and suggest areas for further research.

The purpose of this study is to quantify patterns or trends of electromagnetic ducting conditions in the Arctic. On average, ducts occurred 5% of the time in the summer months, and 2-3% in the spring, fall, and winter months. This is considered a low approximation due to the vertical resolution of the sounding data. For some local regions, ducts occurred up to 20% of the time, especially in summer months. In general, local areas near coast lines or near the pole over ice/ocean had higher frequency of ducts than local areas over land mass. For summer and fall months, humidity gradients contributed most to the formation of a duct, while temperature gradients contributed to a lesser degree. For spring months, temperature gradients contributed most to the formation of the duct, while humidity gradients contributed to a lesser degree. For winter months, due to the extremely cold surface temperatures and low available humidity, temperature gradients were the dominant contribution to duct formation, and humidity gradients worked against duct formation.

This work investigates the breeding success of the Black-throated Diver, Gavia arctica, related to the water quality in three lakes located in the Vallentuna area, north of Stockholm, Sweden.For more than 30 years, I have studied the bird life around these three and other nearby lakes, and noticed that the Black-throated Diver breeds in some lakes, but not in others.The results confirm that the deep and clear lakes Tärnan and Stora Harsjön have good water quality regarding pH, alkalinity, aluminium and Secchi disk values. As expected, the Black-throated Diver shows breeding success in those two lakes, but does not breed in the shallow and eutrophic lake Mysslingen.

Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Animal, 2006.
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O gênero neotropical Cresera Schaus, 1894 é revisado e suas 14 espécies são redescritas. São apresentadas uma chave, ilustrações das genitálias masculinas e femininas dos adultos, bem como venação alar e mapas de distribuição geográfica. Dois sinônimos são estabelecidos: C. simillima (Rothschild, 1933) Syn. n. = C. optima (Butler, 1877); C. intermedia (Rothschild, 1922) Syn. n. = C. hieroglyphica (Schaus, 1905). Duas espécies novas semelhantes a C. ilus (Cramer, 1776) e C. annulata Schaus, 1894 são descritas, sendo que a distinção entre estas espécies baseia-se principalmente nas diferenças entre suas genitálias, antenas e uns poucos caracteres cromáticos. _____________________________________________________________________________ ABSTRACT
The neotropical genus Cresera Schaus, 1894 is revised and its 14 species are redescribed. A key for species, male and female genitalia of adults, as well as wing venation and geographic distribution maps, are provided. Two synonyms are stablished: C. simillima (Rothschild, 1933) Syn. n. = C. optima (Butler, 1877); C. intermedia (Rothschild, 1922) Syn. n. = C. hieroglyphica (Schaus, 1905). Two new species very similar to C. ilus (Cramer, 1776) and C. annulata Schaus, 1894 are described. These species have different antenna, genitalia and a few cromatic characters.

Dispersal can have a multitude of ecological and evolutionary consequences that can be either positive or negative for population fitness and persistence. In this thesis, I describe patterns of dispersal in Arctic Char (Salvelinus alpinus), and I explored some of its consequences. I first examined the consequences of post-glacial dispersal for the distribution of genetic variation across the Canadian range of the species. MtDNA sequences and microsatellite markers provided evidence that the populations of Arctic Char currently inhabiting the Arctic Archipelago probably recolonized from a small glacial refugium, most likely located in ice-free areas of the Archipelago itself. I also presented evidence that two glacial lineages of Char (an Arctic lineage and an Atlantic lineage) probably hybridized post-glacially in the eastern Arctic. Finally, the importance of contemporary dispersal in redistributing genetic variation was illustrated by the fact that anadromous populations have greater within-population genetic diversity, and are less genetically differentiated, than landlocked populations. Second, I used a genetic assignment approach to study patterns of dispersal among populations distributed around Cumberland Sound, Nunavut. Estimates of dispersal rates varied extensively depending on the analysis method used, but all were relatively high compared to other salmonid species. I also found evidence that overwintering individuals have a greater propensity to disperse to non-natal habitats than individuals destined to spawn that year. The consequences of this behaviour for local adaptation among populations was examined using a population genetic model parameterized with estimates of gene flow obtained from microsatellite data. Third, I tested alternative hypotheses for the co-existence of sympatric migratory ecotypes in three lakes of southeast Baffin Island. Microsatellite data showed that the resident and anadromous components of the population are not genetically differentiated, suggesting that migratory behavior is not a genetically fixed trait. Together, the three parts of my thesis provide a general understanding of the patterns and consequences of dispersal for Arctic Char. Since dispersal will be crucial for the response of Arctic Char to environmental change, I conclude by discussing how my work can serve as a foundation for future work on the role of dispersal in adaptation to a changing Arctic.

Arctic Grayling (Thymallus arcticus) are widely distributed on the Arctic Coastal Plain (ACP) of Alaska, and are one of the few upper level consumers in streams, but the trophic pathways and food resources supporting these fish are unknown. Grayling migrate each summer into small beaded streams, which are common across the landscape on the ACP, and appear to be crucial foraging grounds for these and other fishes. I investigated prey resources supporting different size classes of grayling in a beaded stream, Crea Creek, where petroleum development is being planned. The specific objectives were to measure terrestrial prey subsidies entering the stream, quantify prey ingested by Arctic Grayling and Ninespine Stickleback (Pungitius pungitius ), determine if riparian plant species affect the quantity of terrestrial invertebrates ingested by grayling, and determine if prey size and type ingested were a function of predator size. Results indicated that small grayling (< 15 cm fork length (FL)) consumed mostly aquatic invertebrates (caddisflies, midges, and blackflies) early in the summer, and increasing quantities of terrestrial invertebrates (wasps, beetles, and spiders) later in summer, while larger fish (> 15 cm FL) foraged most heavily on stickleback. Riparian plant species influenced the quantity of terrestrial invertebrates entering the stream, however these differences were not reflected in fish diets. This study showed that grayling can be both highly insectivorous and piscivorous, depending upon fish size class, and that both aquatic and terrestrial invertebrates, and especially stickleback, are the main prey of grayling. These results highlight the importance of beaded streams as summer foraging habitats for grayling. Understanding prey flow dynamics in these poorly studied aquatic habitats, prior to further petroleum development and simultaneous climate change, establishes essential baseline information to interpret if and how these freshwater ecosystems may respond to a changing Arctic environment.

The most puzzling aspect of the Canadian relationship with the Arctic region revolves around the split between the appearance of absent-minded governance, bordering on indifference toward the region, and the raging nationalism during moments of actual and perceived challenge toward the imagined “Canadian Arctic region.” Canada’s nationalistic relationship with the Arctic region is often discussed as a reactionary phenomenon to anti-American sentiments, national identity insecurities and government propaganda, but its complexity and evolution within Canadian society are rarely given much in-depth consideration and analysis. As such, this thesis explores the complexities and evolution of the Canadian-Arctic relationship through two central research questions: how have the dominant cultural attitudes about the Canadian Arctic emerged and evolved within Canadian society and how have these cultural ideas about the Canadian Arctic region effected, and been effected by, Canada’s international disputes in the Arctic region? Using Canada as the focus for the analysis, the purpose of this project is to develop upon Arctic studies and international relations literature by providing an intricate look at how interests and disputes in the Canadian Arctic region at the regional and international levels are affects by domestic cultural and political factors.

Theories about how plate tectonics work have existed since the early 1900s, but have not been solidified until more modern times. Since the beginning theories as well as methods have evolved and given new insight of how the Earth works. How it is in constant change and its continents move along its surface. The evolution of the Arctic region have been relatively unknown for some time, but the evolution of new technology and climate change have made parts of the region more accessible for scientific research. This has made understanding of the evolution of the region over time easier. Methods have been developed to either reinforce or disprove others. Theories of how supercontinents have evolved for billions of years and the Arctic regions place in them have been developed. More local areas are also used for proof of different types of interactions between continents like collision and separation to reconstruct where and when these areas have been situated in comparison to different parts of the Earth. This study makes an attempt to show what scientists have come up with within this field and what methods they have used to make their interpretations.

The arctic region is undergoing the most rapid environmental change experienced on Earth, and the rate of change is expected to increase over the coming decades. Arctic coasts are particularly vulnerable because they lie at the interface between terrestrial systems dominated by permafrost and marine systems dominated by sea ice. An increased rise in sea level and degradation of sea-ice as predicted by the Intergovernmental Panel on Climate Change in its most recent report and as observed recently in the Arctic will likely result in greater rates of coastal retreat. An increase in coastal erosion would result in dramatic increases in the volume of sediment, organic carbon and contaminants to the Arctic Ocean. These in turn have the potential to create dramatic changes in the geochemistry and biodiversity of the nearshore zone and affect the Arctic Ocean carbon cycle. To calculate estimates of organic carbon input from coastal erosion to the Arctic Ocean, current methods rely on the length of the coastline in the form of non self-similar line datasets. This thesis however emphasizes that using shorelines drawn at different scales can induce changes in the amount of sediment released by 30% in some cases. It proposes a substitute method of computations of erosion based on areas instead of lengths (i.e. buffers instead of shoreline lengths) which can be easily implemented at the circum-Arctic scale. Using this method, variations in quantities of eroded sediment are, on average, 70% less affected by scale changes and are therefore a more reliable method of calculation. Current estimates of coastal erosion rates in the Arctic are scarce and long-term datasets are a handful, which complicates assessment and prognosis of coastal processes, in particular the occurrence of coastal hazards. This thesis aims at filling the gap by providing the first long-term dataset (1951-2006) of coastal erosion on the Bykovsky Peninsula, North-East Siberia. This study shows that the coastline, which is made of ice-rich permafrost, retreated at a mean annual rate of 0.59 m/yr between 1951and 2006. Rates were highly variable: 97.0 % of the rates observed were less than 2 m/yr and 81.6% were less than 1m/yr. However, no significant trend in erosion could be recorded despite the study of five temporal subperiods within 1951-2006. The juxtaposition of wind records could not help to explain erosion records either and this thesis emphasizes the local controls on erosion, in particular the cryostratigraphy, the proximity of the Peninsula to the Lena River Delta freshwater plume and the local topographical constraints on swell development. On ice-rich coastal stretches of the Artic, the interaction of coastal dynamics and permafrost leads to the occurrence of spectacular “C-shaped” depressions termed retrogressive thaw slumps which can reach lengths of up to 650 m. On Herschel Island and at King Point (Yukon Coastal Plain, northern Canada), topographical, sedimentological and biogeochemical surveys were conducted to investigate the present and past activity of these landforms. In particular, undisturbed tundra areas were compared with zones of former slump activity, now stabilized and re-vegetated. This thesis shows that stabilized areas are drier and less prone to plant growth than undisturbed areas and feature fundamentally different geotechnical properties. Radiocarbon dating and topographical surveys indicated until up to 300 BP a likely period of dramatic slump activity on Herschel Island, similar to the one currently observed, which led to the creation of these surfaces. This thesis hypothesizes the occurrence of a ~250 years cycle of slump activity on the Herschel Island shoreline based on the surveyed topography and cryostratigraphy and anticipates higher frequency of slump activity in the future. The variety of processes described in this thesis highlights the changing nature of the intensity and frequency of physical processes acting upon the arctic coast. It also challenges current perceptions of the threats to existing industry and community infrastructure in the Arctic. The increasing presence of humans on Artic coasts coupled with the expected development of shipping will drive an increase in economical and industrial activity on these coasts which remains to be addressed scientifically.
In der Arktis sind die derzeit stärksten Umweltänderungen weltweit zu beobachten, und es wird angenommen, dass sich deren Ausmaß sogar noch verstärken wird. Aufgrund ihrer Lage zwischen terrestrischen, von Permafrost geprägten Systemen und marinen, von Meereis geprägten Systemen, sind arktische Küstenregionen im Zuge dieses Wandels besonders sensibel. Ein verstärkter Meeresspiegelanstieg und der Rückgang des Meereises, wie vom letzten Bericht des Intergovernmental Panel on Climate Change (IPCC) vorhergesagt und in letzter Zeit in der Arktis beobachtet, werden zu erhöhten Küstenrückzugsraten führen. Ein Anstieg der Küstenerosion würde zu einer drastischen Erhöhung von Sedimentfracht, organischem Kohlenstoff und von Schadstoffen im Arktischen Ozean führen. Durch diese wiederum drohen dramatische Änderungen in der Geochemie und Biodiversität der küstennahen Zone sowie Veränderungen im Kohlenstoffkreislauf des Arktischen Ozeans. Modelle zur Berechnung des Eintrags organischen Kohlenstoffs in den Arktischen Ozean infolge von Küstenerosion basieren auf der Länge der Küstenlinie in Form von „non self-similar“ Datensätzen. Die vorliegende Arbeit zeigt jedoch, dass die Nutzung von Küstenlinien unterschiedlicher Maßstäbe Abweichungen in der berechneten Sedimentfracht von bis zu 30 % zur Folge haben kann. Es wird daher eine alternative Methode zur Berechnung von Erosionsraten vorgeschlagen, die auf Flächen, nicht auf Längenangaben basiert (z.B. Pufferzonen anstelle von Küstenlinien) und die auf einfache Art und Weise für die Zirkum-Arktis angewandt werden kann. Durch diese Methode ist die Variation der berechneten Erosionsmengen um durchschnittlich 70 % weniger von Maßstabsänderungen betroffen. Damit kann eine deutlich höhere Zuverlässigkeit in den Prognosen erreicht werden. Aktuelle Abschätzungen von Küstenerosionsraten in der Arktis sind spärlich und es gibt nur sehr wenige Langzeitdatensätze, so dass Einschätzungen und Prognosen zu Prozessen im Küstenbereich, insbesondere von dessen Gefährdung, schwierig sind. Die vorliegende Arbeit soll dazu beigetragen, diese Lücke zu schließen, indem der erste Langzeitdatensatz (1951-2006) zu Küstenerosionsraten auf der Bykovsky Halbinsel in Nordost-Sibirien bereitgestellt wird. Die Arbeit zeigt, dass die Küstenlinie auf der Bykovsky Halbinsel, die durch eisreichen Permafrost geprägt ist, im Zeitraum 1951-2006 um durchschnittlich 0,59 m pro Jahr zurückging. Die Rückzugsraten waren dabei äußerst variabel: 97 % aller ermittelten Raten betrugen weniger als 2 m und 81,6 % weniger als 1 m pro Jahr. Ein signifikanter Trend in den Erosionsraten konnte dabei jedoch trotz Analyse von fünf verschiedenen zeitlichen Epochen nicht festgestellt werden. Auch die Gegenüberstellung von Winddatensätzen kann die Erosionsraten nicht erklären. Deshalb stellt diese Arbeit die Bedeutung lokaler Kontrollmechanismen wie Kryostratigraphie, die Nähe der Bykovsky Halbinsel zum Lena-Delta und seinen Süßwasservorkommen sowie die lokale Topographie und deren Einfluss auf Wellengang und Wellenbildung heraus. Innerhalb eisreicher arktischer Küstenabschnitte führt die Interaktion zwischen Küstendynamik und Permafrost zur Ausprägung eindrucksvoller, „C-förmiger“ Depressionen, sogenannten regressiven auftaubedingten Rutschungen, die Längen von bis zu 650 m erreichen können. Auf Herschel Island und am King Point (Yukon Küste, Nordkanada) wurden topographische, sedimentologische und biogeochemische Aufnahmen durchgeführt, um die rezente und vergangene Dynamik dieser Landschaftsformen nachvollziehen zu können. Insbesondere wurden ungestörte Tundrenareale mit ehemals aktiven Rutschungszonen, die heute stabil und wiederbewachsen sind, verglichen. Die vorliegende Arbeit zeigt, dass diese ehemaligen, heute stabilisierten Rutschungszonen trockenere und für Pflanzenwachstum weniger geeignete Standorte darstellen als ungestörte Bereiche und überdies fundamental andere geotechnische Eigenschaften aufweisen. Radiocarbon-Datierungen und topographische Aufnahmen weisen darauf hin, dass es auf Herschel Island und am King Point bis vor 300 Jahren eine Periode ausgeprägter, auftaubedingter Rutschungsaktivitäten ähnlich denen, die derzeit auf der Insel beobachtet werden können, gegeben haben muss, die zur Ausbildung dieser Oberflächenstrukturen geführt haben. Diese Arbeit stellt auf Grundlage der untersuchten Topographie und Kryostratigraphie die Hypothese auf, dass an der Küstenlinie von Herschel Island ein etwa 250-jähriger Zyklus von Rutschungsaktivitäten existiert und antizipiert eine höhere Frequenz im Auftreten dieser Rutschungsaktivitäten für die Zukunft. Die Vielfalt an Faktoren, die in dieser Arbeit beschrieben wurden, hebt die veränderte Intensität und Frequenz der auf arktische Küsten einwirkenden physikalischen Prozesse hervor. Dadurch werden auch aktuelle Auffassungen zur Bedrohung bestehender Industrie und Infrastruktur in der Arktis hinterfragt. Im Zusammenhang mit dem erwarteten Ausbau der Schifffahrt treibt der zunehmende anthropogene Einfluss die ökonomische und industrielle Entwicklung in arktischen Küstenregionen an, die Gegenstand einer wissenschaftlichen Betrachtung sein sollten.

During the Arctic summer when the anthropogenic influence is limited, the natural marine source of sulfur in the form of gas-phase dimethyl sulfide viz. DMS(g), is of great importance for cloud formation. The harsh environment of the Arctic makes it difficult to perform in situ measurements of DMS(g) and hence regional model simulations can serve as a complement to increase our understanding of DMS related processes in the Arctic. In this thesis a regional scale meteorological forecast model, extended with DMS(g) calculations, is used to provide a consistent three-dimensional time evolving picture of DMS(g) over the pack-ice region. The analysis focus on meteorological aspects on the horizontal and vertical distribution of DMS(g). Our results show that the amount of DMS(g) over an oceanic source region alone does not determine concentration found over the pack-ice, the prevailing wind also exerts a large influence on the horizontal DMS(g) distribution. The modeled DMS(g) concentrations are advected in plumes in over the pack-ice, which, in combination with the photo-chemical decay, explain the large observed temporal variability of DMS(g) over the pack-ice. The modeled vertical structure show episodes with DMS(g) maxima well above the local boundary layer. Also shown is that DMS(g) maxima can be formed adjacent to frontal zones. In the presence of turbulence DMS(g) can be mixed downwards into the local boundary layer and aid growth to local particles and hence contribute to cloud formation in the boundary layer.
At the time of the doctoral defense the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 4: Manuscript.

Operation of manned oil and gas installations in arctic locations is complicated and presents new challenges. One of the challenges is to maintain the safety of the crew, by obtaining adequate lifeboat systems for crew evacuation. This master thesis focuses on different methods for meeting this challenge. The weather and climate conditions in the Arctic are very different from the conditions we find in more southern oceans. Extreme temperatures, winds caused by polar lows, icing and sea ice presents new and difficult challenges which is demanding for the operation of lifeboats. Hazard identification analyses of two types are performed to identify potential hazards of operating existing lifeboats in arctic conditions. These identify the following hazards as the most critical: Freezing of moving davit components Risk of floating pieces of ice occurring in the launching zone for free fall lifeboats Close pack ice present at the time of evacuation Open drift ice or close pack ice present during the initial operational phase Sea spray icing on the lifeboat at sea Open drift ice or close pack ice present in the operational phase Based on the hazard identification analyses, a specification of requirements for arctic lifeboats is established. This specification is intended to supplement, and not replace, the existing regulations and requirements which apply to lifeboats. Based on the specification, alternatives for modification of existing lifeboats are suggested and discussed. The modification alternatives include modifications of launching equipment, hull strengthening and propulsion equipment. However, full compliance with the specification is not believed to be achievable by modifications. Three different concepts for arctic survival crafts are outlined, each intended for a specific set of ice conditions. Concept one is an arctic free fall lifeboat, intended to be launched by free fall in the icefree summer season, and launched by a more conventional method in the ice season. The lifeboat is designed to be able to operate in higher ice concentrations than existing lifeboats are capable of. Concept two is an arctic conventional lifeboat, intended to be launched in the same way as existing conventional lifeboats. It is designed to operate in very high ice concentrations, by use of Archimedes screws. Concept three is an arctic survival vehicle, designed to operate in continuous ice and very high ice concentrations. Propulsion is provided by twin pair of tracks. In the final part of the thesis, the Arctic Free Fall Lifeboat is developed further. Dimensions, capacities, hull design and features for arctic operation are described. An improved launching arrangement is also described, capable of operating in two different modes depending on the ice concentrations in the area. The thesis concludes that existing lifeboats can be modified to achieve better performance and safety in arctic conditions, but the potential for improvement is limited. To achieve high performance and a high level of safety, arctic lifeboats must be designed and built for this purpose.

Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.
At the time of the doctoral defense the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 4: Manuscript.

The Arctic is warming approximately two time faster than the entire globe, producing considerable local environmental changes that not only affect the fragile Arctic ecosystem but cause also significant socio-economic impacts on the midlatitudes and influence global climate and ocean circulation. In this context the Arctic warm extremes are receiving a growing attention. Until now they have been studied mostly from a overall point of view, considering their mean characteristics and precursors, or focusing on single particularly intense events. This thesis work aims to classify them on the base of their large scale circulation features. Firstly, a definition of Arctic heatwave is proposed, combining the methodology used by some recent studies for identifying Arctic warm extremes with the structure common to the majority of the heatwave definitions used in scientific literature. Then Arctic heatwaves are classified, separately for each season, on the base of their 500-hP a geopotential height anomaly maps in the extra-tropical Northern Hemisphere. Particular attention is given to winter extremes. On the basis of a clustering method, winter events are grouped in three different circulation patterns. Two of these latter are characterized by a pronounced anticyclonic anomaly in the Eurasian sector of the Arctic and by an extensive cold anomaly over southern Siberia (WACE pattern). The third circulation regime is composed by a limited number of events and is countersigned by the prevalence of cyclonic anomalies in the Arctic region. The temporal series of these three regimes shows decadal variations that suggest possible periodicities or Arctic temperature trend dependencies. In the other seasons the circulation regime with the highest number of heatwaves is characterized by an anticyclonic anomaly over the high Arctic. Finally, both on a seasonal level and for single regimes a strong positive correlation between heatwave duration and intensity is observed.

Thesis (M.S. in Meteorology and Physical Oceanography) Naval Postgraduate School, Sept. 2001.
Thesis advisor: Guest, Peter S. "September 2001." Includes bibliographical references (p. 63-64). Also available in print.