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QUARESMA, MATEUS AUGUSTO LIMA, FÁBIO LUIZ DE OLIVEIRA, and DIEGO MATHIAS NATAL DA SILVA. "LEGUMINOUS COVER CROPS FOR BANANA PLANTATIONS IN SEMI-ARID REGIONS." Revista Caatinga 30, no. 3 (September 2017): 614–21. http://dx.doi.org/10.1590/1983-21252017v30n309rc.
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ABSTRACT High temperatures and low rainfall characterize the Brazilian semiarid regions. This regional climate demands the adoption of practices that increase the efficiency and sustainability of local farming. This study aimed to assess the ability of two perennial herbaceous leguminous species, calopo and tropical kudzu, to provide permanent soil cover in banana plantations in Jequitinhonha Valley, northeast Minas Gerais state, Brazil. To this end, we evaluated the differences of calopo and tropical kudzu in soil cover capacity and the amount of senescent phytomass deposited on the soil surface, nutrient content in senescent phytomass, as well as their effects on temperature and soil moisture, compared with bare soil in two experimental sites. The results showed that, compared with tropical kudzu, calopo had a higher soil cover capacity and was more effective at increasing organic material and nutrients in the soil owing to the relatively higher amount of senescent phytomass deposited on the soil surface. However, both calopo and tropical kudzu reduced soil temperature and increase soil moisture compared with bare soil. Overall, we concluded that these species can deposit high levels of senescence in the soil, providing several benefits to the cultivation system of banana plants in the semiarid regions.
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McSweeney, CS, and RN Wesley-Smith. "Factors limiting the intake by sheep of the tropical legume, Calopogonium mucunoides." Australian Journal of Experimental Agriculture 26, no. 6 (1986): 659. http://dx.doi.org/10.1071/ea9860659.
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Sheep were studied to determine whether their low intake of organic matter (400-500 g/day OM) of calopo (Calopogonium mucunoides) was due to toxic properties of the plant, factors that affect its 'acceptability', or to the mineral status of the legume. Practical methods of increasing intake of the harvested plant were also investigated. The low intake by sheep of calopo was not due to its toxicity since supplementation with 500 g/day of ground calopo via the ruminal fistula did not depress voluntary consumption of lucerne hay more than when an equivalent amount of siratro was given. Treatment of the plant with the 'taste-modifiers' monosodium glutumate (2% dry matter fed) and molasses (5%), or with sodium hydroxide 4% w/w or its molar equivalent of potassium hydroxide was associated with an immediate and sustained increase in organic matter intake of about 40%. This intake is similar to that of other tropical forages with similar digestibilities. The taste or odours of the plant therefore appear to limit intake. The low sodium (0.03%) and marginal potassium (0.55%) content of calopo induced a deficiency of these elements in the animal which did not affect intake in the short term. Treatment with molasses had the advantage of supplying extra potassium and energy.
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Chaves, Carla Silva, Karina Guimarães Ribeiro, Odilon Gomes Pereira, Dilermando Miranda da Fonseca, Paulo Roberto Cecon, and Carlos Augusto de Miranda Gomide. "Signal Grass Deferred Pastures Fertilized with Nitrogen or Intercropped with Calopo." Agriculture 11, no. 9 (August 24, 2021): 804. http://dx.doi.org/10.3390/agriculture11090804.
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This study aimed to evaluate the accumulation, structural characteristics, and chemical composition of deferred signal-grass pastures that were subjected to four treatments: without nitrogen fertilization, intercropped with calopo (Calopogonium mucunoides), and fertilized with urea N (50 kg ha−1 and 100 kg ha−1) for 2 years. The design was in randomized blocks, with two blocks and two repetitions of each treatment per block. There were effects of the interaction between treatment and year on green dry mass, forage accumulation, density of vegetative tillers, and crude protein content (simulated grazing). The effects of the treatments on the height, falling index, green dry mass/dead dry mass ratio, number of dead, live and total tillers, and crude protein content (direct cutting) were also observed. Signal-grass–calopo-intercropping ensured adequate mass and forage accumulation and crude protein content equivalent to those of fertilized pastures. In addition, the intercropped pasture showed a higher percentage of leaves and a higher crude protein content compared with those for the other treatments (simulated grazing). The green dry mass/dead dry mass ratio was highest in the intercropped pasture and was equivalent to only that of the pasture fertilized with a low dose of nitrogen. Therefore, signal-grass–calopo-intercropping may be recommended for deferment.
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Alberto Depablos Alviarez, Luis, Bruno Grossi Costa Homem, Paula Hevilen do Couto, José Carlos Batista Dubeux, Thiago Fernandes Bernardes, Daniel Rume Casagrande, and Marcio André Stefanelli Lara. "Managing “Marandu” palisadegrass and calopo pastures based on light interception." Grass and Forage Science 75, no. 4 (September 4, 2020): 447–61. http://dx.doi.org/10.1111/gfs.12501.
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Siqueira da Silva, Hiran Marcelo, José Carlos Batista Dubeux, Mércia Virginia Ferreira dos Santos, Mário de Andrade Lira, Mário de Andrade Lira, and James P. Muir. "Signal Grass Litter Decomposition Rate Increases with Inclusion of Calopo." Crop Science 52, no. 3 (May 2012): 1416–23. http://dx.doi.org/10.2135/cropsci2011.09.0482.
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Sajimin, Sajimin, A. Fanindi, and R. Hutasoit. "PENGARUH METODA PENYIMPANAN TERHADAP VIABILITAS DAN VIGOR BENIH CALOPO (Calopogonium mucunoides)." Pastura 6, no. 2 (January 11, 2019): 98. http://dx.doi.org/10.24843/pastura.2017.v06.i02.p12.
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Calopo (Calopogonium mucunoides) termasuk tanaman penutup tanah yang banyak digunakan di perkebunan di Indonesia. Penelitian ini bertujuan untuk mempelajari kualitas dengan mempelajari daya kecambah benih dengan perbedaan waktu simpan dan perbedaan tempat penyimpan benih. Penelitian dilakukan di laboratorium benih Agrostologi Balai Penelitian Ternak Ciawi-Bogor. Rancangan percobaan acak lengkap dengan perlakuan waktu penyimpanan 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 dan 11 bulan pada tempat penyimpanan yang berbeda yaitu kantang kertas semen, aluminium foil dan kotak plastik. Sebanyak 1 kg benih disimpan sesuai perlakuan di dalam suhu kamar. Kualitas benih dilakukan uji daya kecambah sebanyak 150 biji dibersihkan kemudian diletakan pada petri dish yang berisi 50 biji. Pengamatan dilakukan setiap hari selama 21 hari. Hasil penelitian mengindikasikan penyimpanan semakin lama benih disimpan maka kualitas benih menurun dengan daya kecambahnya semakin rendah. Benih disimpan selama 1 bulan sampai 6 bulan daya kecambahnya 75–84% kemudian penyimpanan 7-11 bulan menurun dengan daya kecambah kurang dari 58,0%. Tempat penyimpanan benih calopo terbaik pada aluminium foil kemudian dikuti dalam kantong kertas semen dan terendah pada kotak plastik.
Kata kunci: kualitas benih, Calopogonium mucunoides, waktu penyimpanan, tempat simpan.
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Barbosa, Juliana Caldeira Victer, Elka Fabiana Aparecida Almeida, Patrícia Duarte de Oliveira Paiva, Marília Andrade Lessa, Lívia Mendes de Carvalho, and Simone Novaes Reis. "Soil management in integrated rose production system." Ornamental Horticulture 25, no. 4 (December 2019): 390–401. http://dx.doi.org/10.1590/2447-536x.v25i4.2018.
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Abstract Integrated production systems have been used with various crops, and their use in floriculture is innovative. The effects of green fertilization in floriculture and the appropriate fertilization levels are still unknown. The aim was to identify the best dose of chemical fertilizer, with or without green fertilization, for integrated production of ‘Carola’ roses. The treatments consisted of 4 doses of the chemical fertilization recommended for rose bushes, (25%, 50%, 75%, and 100%), with or without green fertilization (calopo). Plants that were not treated with 100% (or complete) of chemical fertilization were supplemented monthly with Bokashi (16 g/plant, via the soil) and biofertilizer (5% via the leaves). The assessments were conducted 3 times per week for a year. The use of less chemical fertilizer did not affect rose production or quality, whereas the use of green fertilization did not provide a satisfactory outcome. The analyses, biometric, accumulation and nutrient content, and chemical characteristics of the soil, indicated that green fertilization with calopo was not beneficial. Moreover, with the exception of nitrogen and magnesium, there is the possibility of using 75% of the recommended chemical fertilization in rose bushes.
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Rusdy, Muhammad. "Pengaruh Allelopati Chromolaena odorata terhadap Perkecambahan dan Berat Kering Calopo (Calopogonium muconoides)." Buletin Peternakan 28, no. 4 (December 18, 2012): 148. http://dx.doi.org/10.21059/buletinpeternak.v28i4.1502.
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Santos, Lucas Calazans, Marcela Tonini Venturini, Caroline De Morais Pinheiro, and Eduardo Gross. "GROWTH AND MINERAL COMPOSITION OF TROPICAL FORAGE LEGUMES INOCULATED WITH RHIZOBIA." BRAZILIAN JOURNAL OF AGRICULTURE - Revista de Agricultura 89, no. 3 (January 20, 2015): 252. http://dx.doi.org/10.37856/bja.v89i3.147.
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The objective of this paper was to evaluate the influence of indigenous and inoculated rhizobia and ammonium sulfate fertilizer on growth and mineral composition of the herbaceous legumes, Calopo (Calopogonium mucunoides), Ea Ea (Desmodium heterocarpon subsp. ovalifolium) and Kudzu (Pueraria phaseoloides), which are commonly used as forage plants and cover crops in Brazil. The treatments did not exhibit differences for total biomass of nodules. Lime application along with basic fertilization (without N) permitted nodulation and full growth and development of forages with native rhizobia.
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Calheiros, Altanys Silva, Mario de Andrade Lira Junior, Débora Magalhães Soares, and Márcia do Vale Barreto Figueiredo. "Symbiotic capability of calopo rhizobia from an agrisoil with different crops in Pernambuco." Revista Brasileira de Ciência do Solo 37, no. 4 (August 2013): 869–76. http://dx.doi.org/10.1590/s0100-06832013000400005.
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Biological nitrogen fixation by rhizobium-legume symbiosis represents one of the most important nitrogen sources for plants and depends strongly on the symbiotic efficiency of the rhizobium strain. This study evaluated the symbiotic capacity of rhizobial isolates from calopo (CALOPOGONIUM MUCUNOIDES) taken from an agrisoil under BRACHIARIA DECUMBENS pasture, sabiá (MIMOSA CAESALPINIIFOLIA) plantations and Atlantic Forest areas of the Dry Forest Zone of Pernambuco. A total of 1,575 isolates were obtained from 398 groups. A single random isolate of each group was authenticated, in randomized blocks with two replications. Each plant was inoculated with 1 mL of a bacterial broth, containing an estimated population of 10(8) rhizobial cells mL-1. Forty-five days after inoculation, the plants were harvested, separated into shoots, roots and nodules, oven-dried to constant mass, and weighed. Next, the symbiotic capability was tested with 1.5 kg of an autoclaved sand:vermiculite (1:1) mixture in polyethylene bags. The treatments consisted of 122 authenticated isolates, selected based on the shoot dry matter, five uninoculated controls (treated with 0, 50, 100, 150, or 200 kg ha-1 N) and a control inoculated with SEMIA 6152 (=BR1602), a strain of BRADYRHIZOBIUM JAPONICUM The test was performed as described above. The shoot dry matter of the plants inoculated with the most effective isolates did not differ from that of plants treated with 150 kg ha-1 N. Shoot dry matter was positively correlated with all other variables. The proportion of effective isolates was highest among isolates from SABIÁ forests. There was great variation in nodule dry weight, as well as in N contents and total N.
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Espindola, J. A. A., J. G. M. Guerra, D. L. Almeida, M. G. Teixeira, and S. Urquiaga. "Evaluation of perennial herbaceous legumes with different phosphorus sources and levels in a Brazilian Ultisol." Renewable Agriculture and Food Systems 20, no. 1 (March 2005): 56–62. http://dx.doi.org/10.1079/raf200492.
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AbstractThis study was carried out under field conditions with the aim of evaluating the period of time necessary for soil cover, dry matter production and accumulation of nutrients by perennial herbaceous legumes with different phosphorus sources at different levels. Four legumes were evaluated: calopo (Calopogonium mucunoides Desv.), forage groundnut (Arachis pintoi Krap. & Greg.), siratro (Macroptilium atropurpureum (OC.) Urb.) and tropical kudzu (Pueraria phaseoloides (Roxb.) Benth.). Each of these species received different phosphorus (P) sources and levels: no phosphate fertilization; 44 and 88 kg of P ha−1 applied as rock phosphate; and 44 kg of P ha−1 as triple superphosphate. Calopo, siratro and tropical kudzu completely covered the soil surface 129 days before forage groundnut. Phosphate fertilization did not increase the dry matter production of any species. The legumes forage groundnut, siratro and tropical kudzu showed desirable characteristics that promote their use as cover crops, such as high dry matter production and shoot accumulation of nitrogen (N) and potassium (K). Forage groundnut had the highest proportion of N derived from the atmosphere at the end of the rainy season, while there were no significant differences between the legumes at the end of the dry season. There was an elevation of soil pH and calcium+magnesium (Ca+Mg) contents, associated with a reduction of aluminum (Al) content, in the surface soil layer (0–5 cm) for siratro in relation to groundnut and tropical kudzu. Tropical kudzu promoted higher soil organic C contents when compared to groundnut.
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Adewale Elijah Fadeyi, Saheed Olatunbosun Akiode, Olajide Ebenezer Falayi, Ayodeji Olakunle Fatokun, and Joyce Omohu Orijajogun. "Phytochemical, antioxidant, proximate and FTIR analysis of Calopogonium mucunoides Desv. extracts using selected solvents." World Journal of Biology Pharmacy and Health Sciences 4, no. 1 (October 30, 2020): 014–22. http://dx.doi.org/10.30574/wjbphs.2020.4.1.0069.
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Calopo (Calopogonium mucunoides Desv.), a vigorous, hairy annual trailing legume, is a cover crop in tropical tree plantations. In this study, the aerial part of calopo was extracted separately using hexane, ethylacetate and methanol. The phytochemical constituents and antioxidant activities of the extracts were determined. The nutritional value of the plant was determined by proximate analysis. The FTIR analysis was also carried out. Estimation of the phytochemical and nutritional analysis was done using the standard laboratory methods. The results showed that the total phenolic content of C. mucunoides was the highest (4.29 ± 0.032 mg/g). Antioxidant activity was highest in the methanol extract (65-71% inhibition). Proximate analysis revealed a high protein content (20.54%); ash content (9.86%); Fibre (21.42%); Lipid (18.62%) and carbohydrate content (21.56%). The FTIR analysis showed a broad band at 3392-3353 cm-1 representing bonding –OH groups. The peak around 2924-2918cm-1 represents aliphatic chains, -CH2- and –CH3. The peak around 1623 cm-1 (from methanol and hexane extract only) corresponds to C=O stretch. The peak observed at 1515 cm-1 (from ethylacetate extract) corresponds to the secondary amine group. Results from this study shows the plant contains significant phytochemical compounds and using appropriate solvent, it may serve as a source for the development of novel drugs for the treatment of various diseases as claimed by its traditional uses. The plant is also of high nutritional value, especially due to its high protein and fibre content, and therefore, may be used in feed formulation.
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Omole, A. J. "Performance and Carcass Analysis of Growing Snails Fed Calopogonium mucunoides (Calopo) And Pueraria phaseoloides (Kudzupuero)." Nigerian Journal of Animal Production 37, no. 1 (January 10, 2021): 85–90. http://dx.doi.org/10.51791/njap.v37i1.673.
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An experiment was carried out to determine the effect of feeding growing snails with two different leguminous plants, Calopogonium muculoides, Pueraria phaseoloides, using pawpaw (Carica papaya) leaf as control. A total of 72 growing snails (Archachatina marginata) of mean weight 74.73/3.5g were used for the feeding trial. The snails were randomly alloted into 3 different groups and each group was replicated 4 times with 6 snails per replicate in a completely randomized design. Snails in T1 were fed pawpaw leaf (control), while snails in T2 were fed Calopogolium muculoides. Parameters measured were feed intake, weight gain, shell length and width and feed conversion ratio. The feeding trial lasted for 12 weeks. The results on growth performances reveal that the highest feed intake was recorded in snails fed pawpaw leaf (PL) which was similar to the those fed Pueraria phaseoloids (PP), while the lowest feed intake was recorded in snail fed with Calopognium muculoids (CM). The highest weight gain was also recorded in snails fed with pawpaw leaf and Peuraria phaseoloids (PP) than those fed Calopognium muculoides (CM). In conclusion, Pueraria phaseoloids could be used as substitute for pawpaw leaf.
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Calheiros, Altanys Silva, Mario de Andrade Lira Junior, Mércia Virgínia Ferreira Santos, and Maria do Carmo Catanho Pereira Lyra. "SYMBIOTIC EFFECTIVENESS AND COMPETITIVENESS OF CALOPO RHIZOBIAL ISOLATES IN AN ARGISSOLO VERMELHO-AMARELO UNDER THREE VEGETATION COVERS IN THE DRY FOREST ZONE OF PERNAMBUCO." Revista Brasileira de Ciência do Solo 39, no. 2 (April 2015): 367–76. http://dx.doi.org/10.1590/01000683rbcs20140393.
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Biological N fixation in forage legumes is an important alternative to reduce pasture degradation, and is strongly influenced by the inoculant symbiotic capability. This paper evaluates the effectiveness of Calopo (Calopogonium mucunoides) rhizobial isolated from soil under three vegetation covers of an Argissolo Vermelho-Amarelo of the Dry Forest Zone of Pernambuco. An experiment was conducted evaluating 25 isolates, aside from 5 uninoculated controls with 0; 309; 60; 90 and 120 kg ha-1 N, and a treatment inoculated with the SEMIA 6152 strain. The first cut was performed 45 days after inoculation and a second and third cut after 45-day-intervals. Shoot N content was quantified at all cuts. Shoot dry mass was affected by N rates at all cuts. Shoot dry mass increased from the first to the second cut in inoculated plants. There was no difference between rhizobial isolates from the different plant covers for any of the variables. Most variables were significantly and positively correlated.
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Hu, Yongxiang, David Winker, Mark Vaughan, Bing Lin, Ali Omar, Charles Trepte, David Flittner, et al. "CALIPSO/CALIOP Cloud Phase Discrimination Algorithm." Journal of Atmospheric and Oceanic Technology 26, no. 11 (November 1, 2009): 2293–309. http://dx.doi.org/10.1175/2009jtecha1280.1.
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Abstract The current cloud thermodynamic phase discrimination by Cloud-Aerosol Lidar Pathfinder Satellite Observations (CALIPSO) is based on the depolarization of backscattered light measured by its lidar [Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)]. It assumes that backscattered light from ice crystals is depolarizing, whereas water clouds, being spherical, result in minimal depolarization. However, because of the relationship between the CALIOP field of view (FOV) and the large distance between the satellite and clouds and because of the frequent presence of oriented ice crystals, there is often a weak correlation between measured depolarization and phase, which thereby creates significant uncertainties in the current CALIOP phase retrieval. For water clouds, the CALIOP-measured depolarization can be large because of multiple scattering, whereas horizontally oriented ice particles depolarize only weakly and behave similarly to water clouds. Because of the nonunique depolarization–cloud phase relationship, more constraints are necessary to uniquely determine cloud phase. Based on theoretical and modeling studies, an improved cloud phase determination algorithm has been developed. Instead of depending primarily on layer-integrated depolarization ratios, this algorithm differentiates cloud phases by using the spatial correlation of layer-integrated attenuated backscatter and layer-integrated particulate depolarization ratio. This approach includes a two-step process: 1) use of a simple two-dimensional threshold method to provide a preliminary identification of ice clouds containing randomly oriented particles, ice clouds with horizontally oriented particles, and possible water clouds and 2) application of a spatial coherence analysis technique to separate water clouds from ice clouds containing horizontally oriented ice particles. Other information, such as temperature, color ratio, and vertical variation of depolarization ratio, is also considered. The algorithm works well for both the 0.3° and 3° off-nadir lidar pointing geometry. When the lidar is pointed at 0.3° off nadir, half of the opaque ice clouds and about one-third of all ice clouds have a significant lidar backscatter contribution from specular reflections from horizontally oriented particles. At 3° off nadir, the lidar backscatter signals for roughly 30% of opaque ice clouds and 20% of all observed ice clouds are contaminated by horizontally oriented crystals.
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Yan, Hui, Sheng Xu Luo, Qing Bin Yao, Ya Juan Wang, Yang Yang He, and Yu Jie Xiao. "Study on the Characteristics of Heavy Metal Accumulation in Seven Dominant Plants in Shilu Iron Mines Area of Hainan." Advanced Materials Research 518-523 (May 2012): 2016–21. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.2016.
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Based on the field investigation and sampling, seven dominant wild plants and relative soil samples in Hainan Shilu iron mines area were collected. To analyze and study the contents of heavy metals Pb, Cd, Cu, Fe, Mn and Zn in these samples and the characteristics of enriching heavy metals of these dominant plants. Results of this study showed that the contents of the same heavy metal in the soils around roots system of seven dominant plants had a large range of variation, to a certain extent, it reflected the difference of the enriched characteristics of different plants to the same heavy metal. All seven dominant plants had endurance and enriched characteristics to Fe. Bothriochloa root hoarded up abundant Fe, Cu, Zn and its stored characteristics to Mn, Pb, Cd also stood out from the seven dominant plants, so it could be used as good plant which absorbed a large amount of heavy metals but mainly held in the roots, this result had a good consistance with the finding that the enriched and transferred characteristics of Bothriochloa to heavy metals in soil. In the soil of low cadmium pollution, Calopo and Bothriochloa had higher concentration factors of cadmium, this indicated they had a good potential in high cadmium pollution soil. White tephrosia and Cyperus alternifolius had the higher metastasis ability to Mn, Zn, Cd, which had the potential of phytoremediation.
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Pitts, M. C., L. W. Thomason, L. R. Poole, and D. M. Winker. "Characterization of Polar Stratospheric Clouds with spaceborne lidar: CALIPSO and the 2006 Antarctic season." Atmospheric Chemistry and Physics 7, no. 19 (October 10, 2007): 5207–28. http://dx.doi.org/10.5194/acp-7-5207-2007.
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Abstract. The role of polar stratospheric clouds in polar ozone loss has been well documented. The CALIPSO satellite mission offers a new opportunity to characterize PSCs on spatial and temporal scales previously impossible. A PSC detection algorithm based on a single wavelength threshold approach has been developed for CALIPSO. The method appears to accurately detect PSCs of all opacities, including tenuous clouds, with a very low rate of false positives and few missed clouds. We applied the algorithm to CALIOP data acquired during the 2006 Antarctic winter season from 13 June through 31 October. The spatial and temporal distribution of CALIPSO PSC observations is illustrated with weekly maps of PSC occurrence. The evolution of the 2006 PSC season is depicted by time series of daily PSC frequency as a function of altitude. Comparisons with "virtual" solar occultation data indicate that CALIPSO provides a different view of the PSC season than attained with previous solar occultation satellites. Measurement-based time series of PSC areal coverage and vertically-integrated PSC volume are computed from the CALIOP data. The observed area covered with PSCs is significantly smaller than would be inferred from the commonly used temperature-based proxy TNAT but is similar in magnitude to that inferred from TSTS. The potential of CALIOP measurements for investigating PSC composition is illustrated using combinations of lidar backscatter and volume depolarization for two CALIPSO PSC scenes.
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Pitts, M. C., L. W. Thomason, L. R. Poole, and D. M. Winker. "Characterization of Polar Stratospheric Clouds with Space-Borne Lidar: CALIPSO and the 2006 Antarctic Season." Atmospheric Chemistry and Physics Discussions 7, no. 3 (June 5, 2007): 7933–85. http://dx.doi.org/10.5194/acpd-7-7933-2007.
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Abstract. The role of polar stratospheric clouds in polar ozone loss has been well documented. The CALIPSO satellite mission offers a new opportunity to characterize PSCs on spatial and temporal scales previously impossible. A PSC detection algorithm based on a single wavelength threshold approach has been developed for CALIPSO. The method appears to accurately detect PSCs of all opacities, including tenuous clouds, with a very low rate of false positives and few missed clouds. We applied the algorithm to CALIOP data acquired during the 2006 Antarctic winter season from 13 June through 31 October. The spatial and temporal distribution of CALIPSO PSC observations is illustrated with weekly maps of PSC occurrence. The evolution of the 2006 PSC season is depicted by time series of daily PSC frequency as a function of altitude. Comparisons with "virtual" solar occultation data indicate that CALIPSO provides a different view of the PSC season than attained with previous solar occultation satellites. Measurement-based time series of PSC areal coverage and vertically-integrated PSC volume are computed from the CALIOP data. The observed area covered with PSCs is significantly smaller than would be inferred from the commonly used temperature-based proxy TNAT but is similar in magnitude to that inferred from TSTS . The potential of CALIOP measurements for investigating PSC composition is illustrated using combinations of lidar backscatter and volume depolarization for two CALIPSO PSC scenes.
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Winker, David M., Mark A. Vaughan, Ali Omar, Yongxiang Hu, Kathleen A. Powell, Zhaoyan Liu, William H. Hunt, and Stuart A. Young. "Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms." Journal of Atmospheric and Oceanic Technology 26, no. 11 (November 1, 2009): 2310–23. http://dx.doi.org/10.1175/2009jtecha1281.1.
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Abstract The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is a two-wavelength polarization lidar that performs global profiling of aerosols and clouds in the troposphere and lower stratosphere. CALIOP is the primary instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite, which has flown in formation with the NASA A-train constellation of satellites since May 2006. The global, multiyear dataset obtained from CALIOP provides a new view of the earth’s atmosphere and will lead to an improved understanding of the role of aerosols and clouds in the climate system. A suite of algorithms has been developed to identify aerosol and cloud layers and to retrieve a variety of optical and microphysical properties. CALIOP represents a significant advance over previous space lidars, and the algorithms that have been developed have many innovative aspects to take advantage of its capabilities. This paper provides a brief overview of the CALIPSO mission, the CALIOP instrument and data products, and an overview of the algorithms used to produce these data products.
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Kittaka, C., D. M. Winker, M. A. Vaughan, A. Omar, and L. A. Remer. "Intercomparison of CALIOP and MODIS aerosol optical depth retrievals." Atmospheric Measurement Techniques Discussions 3, no. 4 (August 9, 2010): 3319–44. http://dx.doi.org/10.5194/amtd-3-3319-2010.
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Abstract. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is carried on the CALIPSO satellite and has acquired global aerosol profiles since June 2006. CALIPSO is flown in formation with the Aqua satellite as part of the A-train satellite constellation, so that a large number of coincident aerosol observations are available from CALIOP and the MODIS-Aqua instrument. This study compares column aerosol optical depth at 0.532 μm derived from CALIOP aerosol profiles with MODIS-Aqua 0.55 μm aerosol optical depth over the period June 2006 through August 2008. The study is based on the CALIOP Version 2 Aerosol Layer Product and MODIS Collection 5. While CALIOP is first and foremost a profiling instrument, this comparison of column aerosol optical depth provides insight into quality of CALIOP aerosol data. It is found that daytime aerosol optical depth from the CALIOP Version 2 product has a small global mean bias relative to MODIS Collection 5. Regional biases, of both signs, are larger and biases are seen to vary somewhat with season. In northern mid-latitudes, aerosol optical depth from CALIOP is lower, on average, than from MODIS. This may be partly due to a latitude-dependent calibration error in Version 2 CALIOP Level 1 daytime 0.532 μm profiles. This comparison of CALIOP and MODIS also provides insight into possible biases in the MODIS aerosol optical depth product due to cloud masking and errors in modeling land surface reflectance.
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Alkasem, A., F. Szczap, C. Cornet, V. Shcherbakov, Y. Gour, O. Jourdan, L. C. Labonnote, and G. Mioche. "Effects of cirrus heterogeneity on lidar CALIOP/CALIPSO data." Journal of Quantitative Spectroscopy and Radiative Transfer 202 (November 2017): 38–49. http://dx.doi.org/10.1016/j.jqsrt.2017.07.005.
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Chepfer, H., G. Cesana, D. Winker, B. Getzewich, M. Vaughan, and Z. Liu. "Comparison of Two Different Cloud Climatologies Derived from CALIOP-Attenuated Backscattered Measurements (Level 1): The CALIPSO-ST and the CALIPSO-GOCCP." Journal of Atmospheric and Oceanic Technology 30, no. 4 (April 1, 2013): 725–44. http://dx.doi.org/10.1175/jtech-d-12-00057.1.
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Abstract Two different cloud climatologies have been derived from the same NASA–Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)-measured attenuated backscattered profile (level 1, version 3 dataset). The first climatology, named Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations–Science Team (CALIPSO-ST), is based on the standard CALIOP cloud mask (level 2 product, version 3), with the aim to document clouds with the highest possible spatiotemporal resolution, taking full advantage of the CALIOP capabilities and sensitivity for a wide range of cloud scientific studies. The second climatology, named GCM-Oriented CALIPSO Cloud Product (CALIPSO-GOCCP), is aimed at a single goal: evaluating GCM prediction of cloudiness. For this specific purpose, it has been designed to be fully consistent with the CALIPSO simulator included in the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) used within version 2 of the CFMIP (CFMIP-2) experiment and phase 5 of the Coupled Model Intercomparison Project (CMIP5). The differences between the two datasets in the global cloud cover maps—total, low level (P > 680 hPa), midlevel (680 < P < 440 hPa), and high level (P < 440 hPa)—are frequently larger than 10% and vary with region. The two climatologies show significant differences in the zonal cloud fraction profile (which differ by a factor of almost 2 in some regions), which are due to the differences in the horizontal and vertical averaging of the measured attenuated backscattered profile CALIOP profile before the cloud detection and to the threshold used to detect clouds (this threshold depends on the resolution and the signal-to-noise ratio).
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Kittaka, C., D. M. Winker, M. A. Vaughan, A. Omar, and L. A. Remer. "Intercomparison of column aerosol optical depths from CALIPSO and MODIS-Aqua." Atmospheric Measurement Techniques 4, no. 2 (February 1, 2011): 131–41. http://dx.doi.org/10.5194/amt-4-131-2011.
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Abstract. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is carried on the CALIPSO satellite and has acquired global aerosol profiles since June 2006. CALIPSO is flown in formation with the Aqua satellite as part of the A-train satellite constellation, so that a large number of coincident aerosol observations are available from CALIOP and the MODIS-Aqua instrument. This study compares column aerosol optical depth at 0.532 μm derived from CALIOP aerosol profiles with MODIS-Aqua 0.55 μm aerosol optical depth over the period June 2006 through August 2008. The study is based on the CALIOP Version 2 Aerosol Layer Product and MODIS Collection 5. While CALIOP is first and foremost a profiling instrument, this comparison of column aerosol optical depth provides insight into quality of CALIOP aerosol data. It is found that daytime aerosol optical depth from the CALIOP Version 2 product has only a small global mean bias relative to MODIS Collection 5. Regional biases, of both signs, are larger and biases are seen to vary somewhat with season. Good agreement between the two sensors in ocean regions with low cloudiness suggests that the selection of lidar ratios used in the CALIOP aerosol retrieval is sufficient to provide a regional mean AOD consistent with that retrieved from MODIS. Although differences over land are observed to be larger than over ocean, the bias between CALIOP and MODIS AOD on a regional-seasonal basis is found to be roughly within the envelope of the MODIS expected uncertainty over land and ocean. This work forms a basis for further comparisons using the recently released CALIOP Version 3 data.
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Rogers, R. R., C. A. Hostetler, J. W. Hair, R. A. Ferrare, Z. Liu, M. D. Obland, D. B. Harper, et al. "Assessment of the CALIPSO Lidar 532 nm attenuated backscatter calibration using the NASA LaRC Airborne High Spectral Resolution Lidar." Atmospheric Chemistry and Physics Discussions 10, no. 11 (November 18, 2010): 28355–98. http://dx.doi.org/10.5194/acpd-10-28355-2010.
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Abstract. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC) High Spectral Resolution Lidar (HSRL) was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using an internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that average HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7±2.1% (CALIOP lower) at night and within 2.9±3.9% (CALIOP lower) during the day, demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3.01 calibration scheme compared with the version 2 calibration scheme. Potential systematic uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 3.7% for this validation effort with HSRL. Results from this study are also compared to prior assessments of the CALIOP 532 nm attenuated backscatter calibration.
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Rogers, R. R., C. A. Hostetler, J. W. Hair, R. A. Ferrare, Z. Liu, M. D. Obland, D. B. Harper, et al. "Assessment of the CALIPSO Lidar 532 nm attenuated backscatter calibration using the NASA LaRC airborne High Spectral Resolution Lidar." Atmospheric Chemistry and Physics 11, no. 3 (February 15, 2011): 1295–311. http://dx.doi.org/10.5194/acp-11-1295-2011.
Full textAbstract:
Abstract. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC) High Spectral Resolution Lidar (HSRL) was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% ± 2.1% (CALIOP lower) at night and within 2.9% ± 3.9% (CALIOP lower) during the day, demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3.01 calibration scheme compared with the version 2 calibration scheme. Potential biases and uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 4.5% ± 3.2% for this validation effort with HSRL. Results from this study are also compared with prior assessments of the CALIOP 532 nm attenuated backscatter calibration.
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Winker, D. M., J. Pelon, J. A. Coakley, S. A. Ackerman, R. J. Charlson, P. R. Colarco, P. Flamant, et al. "The CALIPSO Mission." Bulletin of the American Meteorological Society 91, no. 9 (September 1, 2010): 1211–30. http://dx.doi.org/10.1175/2010bams3009.1.
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Aerosols and clouds have important effects on Earth's climate through their effects on the radiation budget and the cycling of water between the atmosphere and Earth's surface. Limitations in our understanding of the global distribution and properties of aerosols and clouds are partly responsible for the current uncertainties in modeling the global climate system and predicting climate change. The CALIPSO satellite was developed as a joint project between NASA and the French space agency CNES to provide needed capabilities to observe aerosols and clouds from space. CALIPSO carries CALIOP, a two-wavelength, polarization-sensitive lidar, along with two passive sensors operating in the visible and thermal infrared spectral regions. CALIOP is the first lidar to provide long-term atmospheric measurements from Earth's orbit. Its profiling and polarization capabilities offer unique measurement capabilities. Launched together with the CloudSat satellite in April 2006 and now flying in formation with the A-train satellite constellation, CALIPSO is now providing information on the distribution and properties of aerosols and clouds, which is fundamental to advancing our understanding and prediction of climate. This paper provides an overview of the CALIPSO mission and instruments, the data produced, and early results.
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Kacenelenbogen, M., M. A. Vaughan, J. Redemann, R. M. Hoff, R. R. Rogers, R. A. Ferrare, P. B. Russell, C. A. Hostetler, J. W. Hair, and B. N. Holben. "An accuracy assessment of the CALIOP/CALIPSO version 2 aerosol extinction product based on a detailed multi-sensor, multi-platform case study." Atmospheric Chemistry and Physics Discussions 10, no. 11 (November 16, 2010): 27967–8015. http://dx.doi.org/10.5194/acpd-10-27967-2010.
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Abstract. The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP's level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that will be introduced in the next version of CALIOP data (version 3, currently being processed). As a first step, we compared CALIOP version 2-derived AOD with the collocated MODerate Imaging Spectroradiometer (MODIS) AOD retrievals over the Continental United States. The best statistical agreement between those two quantities was found over the Eastern part of the United States with, nonetheless, a weak correlation (R ~0.4) and an apparent CALIOP version 2 underestimation (by ~66%) of MODIS AOD. To help quantify the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we then focused on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on August 04, 2007. This case study illustrates the following potential reasons for a bias in the CALIOP AOD: (i) CALIOP's low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth's surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the backscatter-to-extinction ratio (Sa) used in CALIOP's extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles.
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Mitchell, David L., Anne Garnier, Jacques Pelon, and Ehsan Erfani. "CALIPSO (IIR–CALIOP) retrievals of cirrus cloud ice-particle concentrations." Atmospheric Chemistry and Physics 18, no. 23 (December 6, 2018): 17325–54. http://dx.doi.org/10.5194/acp-18-17325-2018.
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Abstract. A new satellite remote sensing method is described whereby the sensitivity of thermal infrared wave resonance absorption to small ice crystals is exploited to estimate cirrus cloud ice-particle number concentration N, effective diameter De and ice water content IWC. This method uses co-located observations from the Infrared Imaging Radiometer (IIR) and from the CALIOP (Cloud and Aerosol Lidar with Orthogonal Polarization) lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) polar orbiting satellite, employing IIR channels at 10.6 and 12.05 µm. Using particle size distributions measured over many flights of the TC4 (Tropical Composition, Cloud and Climate Coupling) and the mid-latitude SPARTICUS (Small Particles in Cirrus) field campaigns, we show for the first time that N∕IWC is tightly related to βeff; the ratio of effective absorption optical depths at 12.05 and 10.6 µm. Relationships developed from in situ aircraft measurements are applied to βeff derived from IIR measurements to retrieve N. This satellite remote sensing method is constrained by measurements of βeff from the IIR and is by essence sensitive to the smallest ice crystals. Retrieval uncertainties are discussed, including uncertainties related to in situ measurement of small ice crystals (D<15 µm), which are studied through comparisons with IIR βeff. The method is applied here to single-layered semi-transparent clouds having a visible optical depth between about 0.3 and 3, where cloud base temperature is ≤235 K. CALIPSO data taken over 2 years have been analyzed for the years 2008 and 2013, with the dependence of cirrus cloud N and De on altitude, temperature, latitude, season (winter vs. summer) and topography (land vs. ocean) described. The results for the mid-latitudes show a considerable dependence on season. In the high latitudes, N tends to be highest and De smallest, whereas the opposite is true for the tropics. The frequency of occurrence of these relatively thick cirrus clouds exhibited a strong seasonal dependence in the high latitudes, with the occurrence frequency during Arctic winter being at least twice that of any other season. Processes that could potentially explain some of these micro- and macroscopic cloud phenomena are discussed.
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Dionisi, Davide, Vittorio Brando, Gianluca Volpe, Simone Colella, and Rosalia Santoleri. "Particulate Optical Properties in the Mediterranean and Black Seas Through Calipso Spaceborne Lidar Measurements." EPJ Web of Conferences 237 (2020): 01014. http://dx.doi.org/10.1051/epjconf/202023701014.
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New applications on global-scale plankton retrievals using the CALIOP (Cloud-Aerosol Lidar with orthogonal Polarization) lidar measurements on the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite recently suggested that space-based lidars could provide information about the depth distribution of optical scattering. Assessing the oceanic surface layer’s optical properties through CALIOP is one of the reasons of the extension of the CALIOP mission for another 3 years (2018-2020). The objective of this work is the evaluation of the potential CALIOP ocean products in the Mediterranean and Black seas using the ocean color products provided by the Copernicus Marine Environment Monitoring Systems (CMEMS).
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Baligar, V. C., M. K. Elson, Z. He, Y. Li, A. de Q. Paiva, A. A. F. Almeida, and D. Ahnert. "Light Intensity Effects on the Growth, Physiological and Nutritional Parameters of Tropical Perennial Legume Cover Crops." Agronomy 10, no. 10 (October 6, 2020): 1515. http://dx.doi.org/10.3390/agronomy10101515.
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In the early stages of the establishment of plantation crops such as cacao, perennial legume cover crops provide vegetative cover to reduce soil and nutrient loss by erosion. Light intensity at cover crop canopy levels greatly influences their adaptability and optimum growth. As tree crops mature, understory cover crops suffer from inadequate light intensity. A greenhouse experiment was undertaken with nine perennial legume cover crop species (Calopo, Ea-Ea, Jack Bean, Lab-Lab, Mucuna ana, Mucuna preta, Cowpea, Black Pigeon Pea and Mixed Pigeon Pea) to assess the effects of three photosynthetic photon flux densities (PPFDs, µmol m−2 s−1) 180 (inadequate light), 450 (moderate light) and 900 (adequate light) on growth, physiological and nutrient uptake parameters. PPFD had highly significant effects on leaf, shoot and root growth parameters and increasing the light intensity from 180 to 900 µmol m−2 s−1 increased all growth parameters with the exception of specific leaf area. In all the legume cover crops, increasing the light intensity significantly increased the net assimilation rates (NAR), SPAD index and net photosynthesis (PN) and its components, stomatal conductance (gs), transpiration (E) and vapor pressure deficit (VPD). Cover crop species, PPFD and their interactions significantly affected water flux (Vo) and various water use efficiency parameters (WUETOTAL, WUEINST and WUEINTR). Increasing the PPFD increased the WUE in all of the cover crops. Species and PPFD had highly significant effects on the uptake of macro- and micronutrients. Overall uptakes of all nutrients were increased with increases in the PPFD from 180 to 900 µmol m−2 s−1. With few exceptions, the nutrient use efficiency (NUE) of the nutrients was significantly influenced by species, PPFD and their interactions. Except for Mn, increasing the PPFD from 180 to 900 µmol m−2 s −1 increased the NUE for all the nutrients.
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Painemal, David, Marian Clayton, Richard Ferrare, Sharon Burton, Damien Josset, and Mark Vaughan. "Novel aerosol extinction coefficients and lidar ratios over the ocean from CALIPSO–CloudSat: evaluation and global statistics." Atmospheric Measurement Techniques 12, no. 4 (April 10, 2019): 2201–17. http://dx.doi.org/10.5194/amt-12-2201-2019.
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Abstract. Aerosol extinction coefficients (σa) and lidar ratios (LRs) are retrieved over the ocean from CALIPSO's Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) attenuated backscatter profiles by solving the lidar equation constrained with aerosol optical depths (AODs) derived by applying the Synergized Optical Depth of Aerosols (SODA) algorithm to ocean surface returns measured by CALIOP and CloudSat's Cloud Profiling Radar. σa and LR are retrieved for two independent scenarios that require somewhat different assumptions: (a) a single homogeneous atmospheric layer (1L) for which the LR is constant with height and (b) a vertically homogeneous layer with a constant LR overlying a marine boundary layer with a homogenous LR fixed at 25 sr (two-layer method, 2L). These new retrievals differ from the standard CALIPSO version 4.1 (V4) product, as the CALIOP–SODA method does not rely on an aerosol classification scheme to select LR. CALIOP–SODA σa and LR are evaluated using airborne high-spectral-resolution lidar (HSRL) observations over the northwest Atlantic. CALIOP–SODA LR (1L and 2L) positively correlates with its HSRL counterpart (linear correlation coefficient r>0.67), with a negative bias smaller than 17.4 % and a good agreement for σa (r≥0.78) with a small negative bias (≤|-9.2%|). Furthermore, a global comparison of optical depths derived by CALIOP–SODA and CALIPSO V4 reveals substantial discrepancies over regions dominated by dust and smoke (0.24), whereas Aqua's Moderate resolution Imaging Spectroradiometer (MODIS) and SODA AOD regional differences are within 0.06. Global maps of CALIOP–SODA LR feature high values over littoral zones, consistent with expectations of continental aerosol transport offshore. In addition, seasonal transitions associated with biomass burning from June to October over the southeast Atlantic are well reproduced by CALIOP–SODA LR.
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Young, Stuart A., Mark A. Vaughan, Anne Garnier, Jason L. Tackett, James D. Lambeth, and Kathleen A. Powell. "Extinction and optical depth retrievals for CALIPSO's Version 4 data release." Atmospheric Measurement Techniques 11, no. 10 (October 18, 2018): 5701–27. http://dx.doi.org/10.5194/amt-11-5701-2018.
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Abstract. The Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud–Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) satellite has been making near-global height-resolved measurements of cloud and aerosol layers since mid-June 2006. Version 4.10 (V4) of the CALIOP data products, released in November 2016, introduces extensive upgrades to the algorithms used to retrieve the spatial and optical properties of these layers, and thus there are both obvious and subtle differences between V4 and previous data releases. This paper describes the improvements made to the extinction retrieval algorithms and illustrates the impacts of these changes on the extinction and optical depth estimates reported in the CALIPSO lidar level 2 data products. The lidar ratios for both aerosols and ice clouds are generally higher than in previous data releases, resulting in generally higher extinction coefficients and optical depths in V4. A newly implemented algorithm for retrieving extinction coefficients in opaque layers is described and its impact examined. Precise lidar ratio estimates are also retrieved in these opaque layers. For semi-transparent cirrus clouds, comparisons between CALIOP V4 optical depths and the optical depths reported by MODIS collection 6 show substantial improvements relative to earlier comparisons between CALIOP version 3 and MODIS collection 5.
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Várnai, T., and A. Marshak. "Analysis of co-located MODIS and CALIPSO observations near clouds." Atmospheric Measurement Techniques Discussions 4, no. 6 (November 14, 2011): 6861–81. http://dx.doi.org/10.5194/amtd-4-6861-2011.
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Abstract. This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS imager can refine our perceptions based on CALIOP lidar measurements about the systematic aerosol changes that occur near clouds. The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies – due mainly to wind drift and differences in view angle – do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. The global median distance to clouds in maritime clear-sky areas is in the 4–5 km range.
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Kacenelenbogen, M., M. A. Vaughan, J. Redemann, R. M. Hoff, R. R. Rogers, R. A. Ferrare, P. B. Russell, C. A. Hostetler, J. W. Hair, and B. N. Holben. "An accuracy assessment of the CALIOP/CALIPSO version 2/version 3 daytime aerosol extinction product based on a detailed multi-sensor, multi-platform case study." Atmospheric Chemistry and Physics 11, no. 8 (April 29, 2011): 3981–4000. http://dx.doi.org/10.5194/acp-11-3981-2011.
Full textAbstract:
Abstract. The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP's level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. space-borne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth's Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP's low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth's surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP's extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case study seems to partially fix factor (i) although the aerosol retrieved by CALIOP is still somewhat lower than the profile measured by HSRL; the cloud contamination (ii) appears to be corrected; no particular change is apparent in the observation-based CALIOP Sa value (iii). Our case study also showed very little difference in version 2 and version 3 CALIOP attenuated backscatter coefficient profiles, illustrating a minor change in the calibration scheme (iv).
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Lopes, F. J. S., E. Landulfo, and M. A. Vaughan. "Evaluating CALIPSO's 532 nm lidar ratio selection algorithm using AERONET sun photometers in Brazil." Atmospheric Measurement Techniques 6, no. 11 (November 28, 2013): 3281–99. http://dx.doi.org/10.5194/amt-6-3281-2013.
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Abstract. Since the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite first began probing the Earth's atmosphere on 13 June 2006, several research groups dedicated to investigating the atmosphere's optical properties have conducted measurement campaigns to validate the CALIPSO data products. Recently, in order to address the lack of CALIPSO validation studies in the Southern Hemisphere, and especially the South American continent, the Lasers Environmental Applications Research Group at Brazil's Nuclear and Energy Research Institute (IPEN) initiated efforts to assess CALIPSO's aerosol lidar ratio estimates using the AERONET sun photometers installed at five different locations in Brazil. In this study we develop a validation methodology to evaluate the accuracy of the modeled values of the lidar ratios used by the CALIPSO extinction algorithms. We recognize that the quality of any comparisons between satellite and ground-based measurements depends on the degree to which the instruments are collocated, and that even selecting the best spatial and temporal matches does not provide an unequivocal guarantee that both instruments are measuring the same air mass. The validation methodology presented in this study therefore applies backward and forward air mass trajectories in order to obtain the best possible match between the air masses sampled by the satellite and the ground-based instruments, and thus reduces the uncertainties associated with aerosol air mass variations. Quantitative comparisons of lidar ratios determined from the combination of AERONET optical depth measurements and CALIOP integrated attenuated backscatter measurements show good agreement with the model values assigned by the CALIOP algorithm. These comparisons yield a mean percentage difference of −1.5% ± 24%. This result confirms the accuracy in the lidar ratio estimates provided by the CALIOP algorithms over Brazil to within an uncertainty range of no more than 30%.
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Tesche, Matthias, Peggy Achtert, and Michael C. Pitts. "On the best locations for ground-based polar stratospheric cloud (PSC) observations." Atmospheric Chemistry and Physics 21, no. 1 (January 15, 2021): 505–16. http://dx.doi.org/10.5194/acp-21-505-2021.
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Abstract. Spaceborne observations of polar stratospheric clouds (PSCs) with the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provide a comprehensive picture of the occurrence of Arctic and Antarctic PSCs as well as their microphysical properties. However, advances in understanding PSC microphysics also require measurements with ground-based instruments, which are often superior to CALIOP in terms of, for example, time resolution, measured parameters, and signal-to-noise ratio. This advantage is balanced by the location of ground-based PSC observations and their dependence on tropospheric cloudiness. CALIPSO observations during the boreal winters from December 2006 to February 2018 and the austral winters 2012 and 2015 are used to assess the effect of tropospheric cloudiness and other measurement-inhibiting factors on the representativeness of ground-based PSC observations with lidar in the Arctic and Antarctic, respectively. Information on tropospheric and stratospheric clouds from the CALIPSO Cloud Profile product (05kmCPro version 4.10) and the CALIPSO polar stratospheric cloud mask version 2, respectively, is combined on a profile-by-profile basis to identify conditions under which a ground-based lidar is likely to perform useful measurements for the analysis of PSC occurrence. It is found that the location of a ground-based measurement together with the related tropospheric cloudiness can have a profound impact on the derived PSC statistics and that these findings are rarely in agreement with polewide results from CALIOP observations. Considering the current polar research infrastructure, it is concluded that the most suitable sites for the expansion of capabilities for ground-based lidar observations of PSCs are Summit and Villum in the Arctic and Mawson, Troll, and Vostok in the Antarctic.
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Várnai, T., and A. Marshak. "Analysis of co-located MODIS and CALIPSO observations near clouds." Atmospheric Measurement Techniques 5, no. 2 (February 17, 2012): 389–96. http://dx.doi.org/10.5194/amt-5-389-2012.
Full textAbstract:
Abstract. This paper aims at helping synergistic studies in combining data from different satellites for gaining new insights into two critical yet poorly understood aspects of anthropogenic climate change, aerosol-cloud interactions and aerosol radiative effects. In particular, the paper examines the way cloud information from the MODIS (MODerate resolution Imaging Spectroradiometer) imager can refine our perceptions based on CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar measurements about the systematic aerosol changes that occur near clouds. The statistical analysis of a yearlong dataset of co-located global maritime observations from the Aqua and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellites reveals that MODIS's multispectral imaging ability can greatly help the interpretation of CALIOP observations. The results show that imagers on Aqua and CALIPSO yield very similar pictures, and that the discrepancies – due mainly to wind drift and differences in view angle – do not significantly hinder aerosol measurements near clouds. By detecting clouds outside the CALIOP track, MODIS reveals that clouds are usually closer to clear areas than CALIOP data alone would suggest. The paper finds statistical relationships between the distances to clouds in MODIS and CALIOP data, and proposes a rescaling approach to statistically account for the impact of clouds outside the CALIOP track even when MODIS cannot reliably detect low clouds, for example at night or over sea ice. Finally, the results show that the typical distance to clouds depends on both cloud coverage and cloud type, and accordingly varies with location and season. In maritime areas perceived cloud free, the global median distance to clouds below 3 km altitude is in the 4–5 km range.
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Kim, S. W., S. Berthier, P. Chazette, J. C. Raut, F. Dulac, and S. C. Yoon. "Validation of aerosol and cloud layer structures from the space-borne lidar CALIOP using Seoul National University ground-based lidar." Atmospheric Chemistry and Physics Discussions 7, no. 4 (August 1, 2007): 11207–22. http://dx.doi.org/10.5194/acpd-7-11207-2007.
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Abstract. We present first observationally based validations of the space-borne lidar CALIOP onboard CALIPSO satellite using coincidental observations from a ground-based SNU lidar for 3 different types of atmospheric scenes. Both lidar measurements were taken in nearly same airmass in space and time. Total attenuated backscatters at 532 nm from the two instruments show similar aerosol and cloud layer structures (the top and bottom heights) both under cloud-free conditions and in case of multi-aerosol layers underlying semi-transparent cirrus clouds. This result confirms that the CALIPSO science team algorithms of the discrimination of cloud and aerosol as well as of their layer top and base altitudes are sound. Under thick clouds conditions, only information on the cloud top (bottom) height is reliable from CALIOP (ground-based lidar) observations due to strong signal attenuations. However, simultaneous space-borne CALIOP and ground-based SNU lidar measurements complement each other and provide full information on the vertical distribution of aerosols and clouds. Discrepancies between space-borne and ground-based lidar signals are partly explained by the strong spatial and vertical inhomogeneous distributions of clouds at few kilometer horizontal scales.
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Kanitz, T., A. Ansmann, A. Foth, P. Seifert, U. Wandinger, R. Engelmann, H. Baars, D. Althausen, C. Casiccia, and F. Zamorano. "Surface matters: limitations of CALIPSO V3 aerosol typing in coastal regions." Atmospheric Measurement Techniques 7, no. 7 (July 10, 2014): 2061–72. http://dx.doi.org/10.5194/amt-7-2061-2014.
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Abstract. In the CALIPSO data analysis, surface type (land/ocean) is used to augment the aerosol characterization. However, this surface-dependent aerosol typing prohibits a correct classification of marine aerosol over land that is advected from ocean to land. This might result in a systematic overestimation of the particle extinction coefficient and of the aerosol optical thickness (AOT) of up to a factor of 3.5 over land in coastal areas. We present a long-term comparison of CALIPSO and ground-based lidar observations of the aerosol conditions in the coastal environment of southern South America (Punta Arenas, Chile, 53° S), performed in December 2009–April 2010. Punta Arenas is almost entirely influenced by marine particles throughout the year, indicated by a rather low AOT of 0.02–0.04. However, we found an unexpectedly high fraction of continental aerosol in the aerosol types inferred by means of CALIOP observations and, correspondingly, too high values of particle extinction. Similar features of the CALIOP data analysis are presented for four other coastal areas around the world. Since CALIOP data serve as important input for global climate models, the influence of this systematic error was estimated by means of simplified radiative-transfer calculations.
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Kanitz, T., A. Ansmann, A. Foth, P. Seifert, U. Wandinger, R. Engelmann, H. Baars, D. Althausen, C. Casiccia, and F. Zamorano. "Surface matters: limitations of CALIPSO V3 aerosol typing in coastal regions." Atmospheric Measurement Techniques Discussions 7, no. 2 (February 11, 2014): 1333–65. http://dx.doi.org/10.5194/amtd-7-1333-2014.
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Abstract. In the CALIPSO data analysis the surface type (land/ocean) is used to augment the aerosol characterization. However, this surface-dependent aerosol typing prohibits a correct classification of sea-breeze-related marine aerosol over land. This might result in a systematic overestimation of the particle extinction coefficient and of the aerosol optical thickness (AOT) of up to a factor of 3.5 over land in coastal areas. We present a long-term comparison of CALIPSO and ground-based lidar observations of the aerosol conditions in the coastal environment of southern Latin America (Punta Arenas, Chile, 53° S), performed in December 2009–April 2010. Punta Arenas is almost entirely influenced by marine particles throughout the year, indicated by a rather low AOT of 0.02–0.04. However, we found an unexpectedly high fraction of continental aerosol in the aerosol types inferred by means of CALIOP observations and, correspondingly, too high particle extinction values. Similar features of the CALIOP data analysis are presented for four other coastal areas around the world. Since CALIOP data serve as important input for global climate models, the influence of this systematic error was estimated by means of simplified radiative-transfer calculations.
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Lu, Xiaomei, Yongxiang Hu, Ali Omar, Rosemary Baize, Mark Vaughan, Sharon Rodier, Jayanta Kar, et al. "Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects." Remote Sensing 13, no. 14 (July 14, 2021): 2769. http://dx.doi.org/10.3390/rs13142769.
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Recent studies indicate that the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provides valuable information about ocean phytoplankton distributions. CALIOP’s attenuated backscatter coefficients, measured at 532 nm in receiver channels oriented parallel and perpendicular to the laser’s linear polarization plane, are significantly improved in the Version 4 data product. However, due to non-ideal instrument effects, a small fraction of the backscattered optical power polarized parallel to the receiver polarization reference plane is misdirected into the perpendicular channel, and vice versa. This effect, known as polarization crosstalk, typically causes the measured perpendicular signal to be higher than its true value and the measured parallel signal to be lower than its true value. Therefore, the ocean optical properties derived directly from CALIOP’s measured signals will be biased if the polarization crosstalk effect is not taken into account. This paper presents methods that can be used to estimate the CALIOP crosstalk effects from on-orbit measurements. The global ocean depolarization ratios calculated both before and after removing the crosstalk effects are compared. Using CALIOP crosstalk-corrected signals is highly recommended for all ocean subsurface studies.
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Powell, Kathleen A., Chris A. Hostetler, Mark A. Vaughan, Kam-Pui Lee, Charles R. Trepte, Raymond R. Rogers, David M. Winker, et al. "CALIPSO Lidar Calibration Algorithms. Part I: Nighttime 532-nm Parallel Channel and 532-nm Perpendicular Channel." Journal of Atmospheric and Oceanic Technology 26, no. 10 (October 1, 2009): 2015–33. http://dx.doi.org/10.1175/2009jtecha1242.1.
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Abstract The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission was launched in April 2006 and has continuously acquired collocated multisensor observations of the spatial and optical properties of clouds and aerosols in the earth’s atmosphere. The primary payload aboard CALIPSO is the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), which makes range-resolved measurements of elastic backscatter at 532 and 1064 nm and linear depolarization ratios at 532 nm. CALIOP measurements are important in reducing uncertainties that currently limit understanding of the global climate system, and it is essential that these measurements be accurately calibrated. This work describes the procedures used to calibrate the 532-nm measurements acquired during the nighttime portions of the CALIPSO orbits. Accurate nighttime calibration of the 532-nm parallel-channel data is fundamental to the success of the CALIOP measurement scheme, because the nighttime calibration is used to infer calibration across the day side of the orbits and all other channels are calibrated relative to the 532-nm parallel channel. The theoretical basis of the molecular normalization technique as applied to space-based lidar measurements is reviewed, and a comprehensive overview of the calibration algorithm implementation is provided. Also included is a description of a data filtering procedure that detects and removes spurious high-energy events that would otherwise introduce large errors into the calibration. Error estimates are derived and comparisons are made to validation data acquired by the NASA airborne high–spectral resolution lidar. Similar analyses are also presented for the 532-nm perpendicular-channel calibration technique.
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Léon, Jean-François, Nadège Martiny, and Sébastien Merlet. "A Multi Linear Regression Model to Derive Dust PM10 in the Sahel Using AERONET Aerosol Optical Depth and CALIOP Aerosol Layer Products." Remote Sensing 12, no. 18 (September 22, 2020): 3099. http://dx.doi.org/10.3390/rs12183099.
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Due to a limited number of monitoring stations in Western Africa, the impact of mineral dust on PM10 surface concentrations is still poorly known. We propose a new method to retrieve PM10 dust surface concentrations from sun photometer aerosol optical depth (AOD) and CALIPSO/CALIOP Level 2 aerosol layer products. The method is based on a multi linear regression model that is trained using co-located PM10, AERONET and CALIOP observations at 3 different locations in the Sahel. In addition to the sun photometer AOD, the regression model uses the CALIOP-derived base and top altitude of the lowermost dust layer, its AOD, the columnar total and columnar dust AOD. Due to the low revisit period of the CALIPSO satellite, the monthly mean annual cycles of the parameters are used as predictor variables rather than instantaneous observations. The regression model improves the correlation coefficient between monthly mean PM10 and AOD from 0.15 (AERONET AOD only) to 0.75 (AERONET AOD and CALIOP parameters). The respective high and low PM10 concentration during the winter dry season and summer season are well produced. Days with surface PM10 above 100 μg/m3 are better identified when using the CALIOP parameters in the multi linear regression model. The number of true positives (actual and predicted concentrations above the threshold) is increased and leads to an improvement in the classification sensitivity (recall) by a factor 1.8. Our methodology can be extrapolated to the whole Sahel area provided that satellite derived AOD maps are used in order to create a new dataset on population exposure to dust events in this area.
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Lopes, F. J. S., E. Landulfo, and M. A. Vaughan. "Assessment of the CALIPSO Lidar 532 nm version 3 lidar ratio models using a ground-based lidar and AERONET sun photometers in Brazil." Atmospheric Measurement Techniques Discussions 6, no. 1 (February 1, 2013): 1143–99. http://dx.doi.org/10.5194/amtd-6-1143-2013.
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Abstract. Since the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite first began probing the Earth's atmosphere on 13 June 2006, several research groups dedicated to investigating the atmosphere's optical properties have conducted measurement campaigns to validate the CALIPSO data products. Recently, in order to address the lack of CALIPSO validation studies in the Southern Hemisphere, and especially the South American continent, the Lasers Environmental Applications Research Group at Brazil's Nuclear and Energy Research Institute (IPEN) initiated efforts to assess CALIPSO's aerosol lidar ratio estimates using two ground-based remote sensing instruments: a single elastic backscatter lidar system and the AERONET sun photometers installed at five different locations in Brazil. In this study we develop a validation methodology to assess the accuracy of the modeled values of the lidar ratios used by the CALIPSO extinction algorithms. We recognize that the quality of any comparisons between satellite and ground-based measurements depends on the degree to which the instruments are collocated, and that even selecting the best spatial and temporal matches does not provide an unequivocal guarantee that both instruments are measuring the same air mass. The validation methodology presented in this study therefore applies backward and forward air mass trajectories in order to obtain the best possible match between the air masses sampled by the satellite and the ground-based instruments, and thus reduces the uncertainties associated with aerosol air mass variations. Quantitative comparisons of lidar ratio values determined from the combination of AERONET optical depth measurements and CALIOP integrated attenuated backscatter show good agreement with the model values assigned by the CALIOP algorithm. These comparisons yield a mean percentage difference of −2% ± 26%. Similarly, lidar ratio values retrieved by the elastic backscatter lidar system at IPEN show a mean percentage difference of −2% ± 15% when compared with CALIOP's lidar ratio. These results confirm the accuracy in the lidar ratio estimates provided by the CALIOP algorithms to within an uncertainty range of no more than 30%.
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Córdoba-Jabonero, C., J. L. Guerrero-Rascado, D. Toledo, M. Parrondo, M. Yela, M. Gil, and H. A. Ochoa. "Depolarization ratio of polar stratospheric clouds in coastal Antarctica: comparison analysis between ground-based Micro Pulse Lidar and space-borne CALIOP observations." Atmospheric Measurement Techniques 6, no. 3 (March 14, 2013): 703–17. http://dx.doi.org/10.5194/amt-6-703-2013.
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Abstract. Polar stratospheric clouds (PSCs) play an important role in polar ozone depletion, since they are involved in diverse ozone destruction processes (chlorine activation, denitrification). The degree of that ozone reduction is depending on the type of PSCs, and hence on their occurrence. Therefore PSC characterization, mainly focused on PSC-type discrimination, is widely demanded. The backscattering (R) and volume linear depolarization (δV) ratios are the parameters usually used in lidar measurements for PSC detection and identification. In this work, an improved version of the standard NASA/Micro Pulse Lidar (MPL-4), which includes a built-in depolarization detection module, has been used for PSC observations above the coastal Antarctic Belgrano II station (Argentina, 77.9° S 34.6° W, 256 m a.s.l.) since 2009. Examination of the MPL-4 δV feature as a suitable index for PSC-type discrimination is based on the analysis of the two-channel data, i.e., the parallel (p-) and perpendicular (s-) polarized MPL signals. This study focuses on the comparison of coincident δV-profiles as obtained from ground-based MPL-4 measurements during three Antarctic winters with those reported from the space-borne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite in the same period (83 simultaneous cases are analysed for 2009–2011 austral winter times). Three different approaches are considered for the comparison analysis between both lidar profile data sets in order to test the degree of agreement: the correlation coefficient (CC), as a measure of the relationship between both PSC vertical structures; the mean differences together with their root mean square (RMS) values found between data sets; and the percentage differences (BIAS), parameter also used in profiling comparisons between CALIOP and other ground-based lidar systems. All of them are examined as a function of the CALIPSO ground-track distance from the Belgrano II station. Results represent a relatively good agreement between both ground-based MPL-4 and space-borne CALIOP profiles of the volume linear depolarization ratio δV for PSC events, once the MPL-4 depolarization calibration parameters are applied. Discrepancies between CALIOP and MPL-4 profiles in vertical layering structure are enhanced from 20 km up, likely due to a decrease of the signal-to-noise ratio (SNR) for both lidar systems at those altitudes. Regarding the results obtained from the mean and the percentage differences found between MPL-4 and CALIOP δV profiles, a predominance of negative values is also observed, indicating a generalized underestimation of the MPL-4 depolarization as compared to that reported by CALIOP. However, absolute differences between those δV-profile data sets are no higher than a 10 ± 11% in average. Moreover, the degree of agreement between both lidar δV data sets is slightly dependent on the CALIPSO ground-track overpass distance from the Belgrano II station. That is, small discrepancies are found when CALIPSO ground-track distance is as close as far from the ground-based station. These results would indicate that MPL-4 depolarization observations would reflect relatively well the PSC field that CALIOP can detect at relatively large distances from the ground-based station. As a consequence, PSC properties can be statistically similar, on average, over large volumes, and hence the present weak disagreement found between both the lidar δV data sets can be likely dominated by small spatial PSC inhomogeneities along the CALIPSO separation from the station. This statement is based on the fact that Belgrano II is a station located well inside the stable Antarctic polar vortex, allowing determined thermodynamic conditions leading to a very low variability in the PSC field, and in their properties.
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Royer, P., J. C. Raut, G. Ajello, S. Berthier, and P. Chazette. "Synergy between CALIOP and MODIS instruments for aerosol monitoring: application to the Po Valley." Atmospheric Measurement Techniques 3, no. 4 (July 9, 2010): 893–907. http://dx.doi.org/10.5194/amt-3-893-2010.
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Abstract. In this study aerosol optical properties are studied over the Po Valley from June 2006 to February 2009 using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations/Cloud-Aerosol LIdar with Orthogonal Polarization (CALIPSO/CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua and Terra. The choice of the Po valley has been driven by the numerous occurrences of pollutant events leading to a mean MODIS-derived aerosol optical depth (AOD) of 0.27 (±0.17) at 550 nm over a large area of ~120 000 km2. AOD derived from MODIS, AERONET and CALIOP have been compared. The comparison with AERONET sun-photometers has highlighted an overestimation of AOD from MODIS radiometers of 0.047 for Aqua and 0.088 for Terra. A systematic underestimation of AOD derived from CALIOP Level-2 products has been observed in comparison to Aqua (0.060) and Terra (0.075) MODIS values. Considering those discrepancies a synergistic approach combining CALIOP level-1 data and MODIS AOD has been developed for the first time over land to retrieve the equivalent extinction-to-backscatter ratio at 532 nm (LR). MODIS-derived AOD were indeed used to constrain CALIOP profiles inversion. A significant number of CALIOP level-1 vertical profiles have been averaged (~200 individual laser shots) in the Po Valley, leading to a signal-to-noise ratio (SNR) higher than 10 in the planetary boundary layer (PBL), which is sufficient to invert the mean lidar profiles. The mean LR (together with the associated variabilities) over the Po Valley retrieved from the coupling between CALIOP/MODIS-Aqua and CALIOP/MODIS-Terra are ~78±22 sr and ~86±27 sr, respectively. The total uncertainty on LR retrieval has been assessed to be ~12 sr using a Monte Carlo approach. The mean LR determined from a look-up table through a selection algorithm in CALIOP level 2 operational products (~63±8 sr) show a good agreement for daytime inversion (70±11 sr for Aqua and 74±14 sr for Terra). These values appear close to what is expected for pollution aerosols in an urban area. Contrarily large differences are observed when considering nighttime CALIOP profiles inverted with daytime AOD from MODIS (63±7 sr for CALIOP level-2 compared with 89±28 sr for CALIOP/Aqua and 103±32 sr for CALIOP/Terra synergies). They can be explained by a significant evolution of AOD between lidar and radiometer passing times. In most of cases, the mean aerosol extinction coefficient in the PBL significantly differs between the level-2 operational products and the result CALIPSO/MODIS synergy results. Mean differences of 0.10 km−1 (~50%) and 0.13 km−1 (~60%) have indeed been calculated using MODIS-Aqua/CALIOP and MODIS-Terra/CALIOP coupling studies, respectively. Such differences may be due to the identification of the aerosol model by the operational algorithm and thus to the choice of the LR.
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Kim, S. W., S. Berthier, J. C. Raut, P. Chazette, F. Dulac, and S. C. Yoon. "Validation of aerosol and cloud layer structures from the space-borne lidar CALIOP using a ground-based lidar in Seoul, Korea." Atmospheric Chemistry and Physics 8, no. 13 (July 11, 2008): 3705–20. http://dx.doi.org/10.5194/acp-8-3705-2008.
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Abstract. We present initial validation results of the space-borne lidar CALIOP onboard CALIPSO satellite using coincidental observations from a ground-based lidar in Seoul National University (SNU), Seoul, Korea (37.46° N, 126.95° E). We analyze six selected cases between September 2006 and February 2007, including 3 daytime and 3 night-time observations and covering different types of clear and cloudy atmospheric conditions. Apparent scattering ratios calculated from the two lidar measurements of total attenuated backscatter at 532 nm show similar aerosol and cloud layer structures both under cloud-free conditions and in cases of multiple aerosol layers underlying semi-transparent cirrus clouds. Agreement on top and base heights of cloud and aerosol layers is generally within 0.10 km, particularly during night-time. This result confirms that the CALIPSO science team algorithms for the discrimination of cloud and aerosol as well as for the detection of layer top and base altitude provide reliable information in such atmospheric conditions. This accuracy of the planetary boundary layer top height under cirrus cloud appears, however, limited during daytime. Under thick cloud conditions, however, information on the cloud top (bottom) height only is reliable from CALIOP (ground-based lidar) due to strong signal attenuations. However, simultaneous space-borne CALIOP and ground-based SNU lidar (SNU-L) measurements complement each other and can be combined to provide full information on the vertical distribution of aerosols and clouds. An aerosol backscatter-to-extinction ratio (BER) estimated from lidar and sunphotometer synergy at the SNU site during the CALIOP overpass is assessed to be 0.023±0.004 sr−1 (i.e. a lidar ratio of 43.2±6.2 sr) from CALIOP and 0.027±0.006 sr−1 (37.4±7.2 sr) from SNU-L. For aerosols within the planetary boundary layer under cloud-free conditions, the aerosol extinction profiles from both lidars are in agreement within about 0.02 km−1. Under semi-transparent cirrus clouds, such profiles also show good agreement for the night-time CALIOP flight, but large discrepancies are found for the daytime flights due to a small signal-to-noise ratio of the CALIOP data.
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Burton, S. P., R. A. Ferrare, M. A. Vaughan, A. H. Omar, R. R. Rogers, C. A. Hostetler, and J. W. Hair. "Aerosol classification from airborne HSRL and comparisons with the CALIPSO vertical feature mask." Atmospheric Measurement Techniques Discussions 6, no. 1 (February 14, 2013): 1815–58. http://dx.doi.org/10.5194/amtd-6-1815-2013.
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Abstract. Aerosol classification products from the NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft are compared with coincident V3.01 aerosol classification products from the CALIOP instrument on the CALIPSO satellite. For CALIOP, aerosol classification is a key input to the aerosol retrieval, and must be inferred using aerosol loading-dependent observations and location information. In contrast, HSRL-1 makes direct measurements of aerosol intensive properties, including the lidar ratio, that provide information on aerosol type. In this study, comparisons are made for 109 underflights of the CALIOP orbit track. We find that 62% of the CALIOP marine layers and 54% of the polluted continental layers agree with HSRL-1 classification results. In addition, 80% of the CALIOP desert dust layers are classified as either dust or dusty mix by HSRL-1. However, agreement is less for CALIOP smoke (13%) and polluted dust (35%) layers. Specific case studies are examined, giving insight into the performance of the CALIOP aerosol type algorithm. In particular, we find that the CALIOP polluted dust type is overused due to an attenuation-related depolarization bias. Furthermore, the polluted dust type frequently includes mixtures of dust plus marine aerosol. Finally, we find that CALIOP's identification of internal boundaries between different aerosol types in contact with each other frequently do not reflect the actual transitions between aerosol types accurately. Based on these findings, we give recommendations which may help to improve the CALIOP aerosol type algorithms.
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Pitts, M. C., L. R. Poole, and L. W. Thomason. "CALIPSO polar stratospheric cloud observations: second-generation detection algorithm and composition discrimination." Atmospheric Chemistry and Physics Discussions 9, no. 2 (March 27, 2009): 8121–57. http://dx.doi.org/10.5194/acpd-9-8121-2009.
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Abstract. This paper focuses on polar stratospheric cloud (PSC) measurements by the CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) lidar system onboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) spacecraft, which has been operating since June 2006. We describe a second-generation PSC detection algorithm that utilizes both the CALIOP 532-nm scattering ratio (ratio of total-to-molecular backscatter coefficients) and 532-nm perpendicular backscatter coefficient measurements for cloud detection. The inclusion of the perpendicular backscatter measurements enhances the detection of tenuous PSC mixtures containing low number densities of solid particles and leads to about a 15% increase in PSC areal coverage compared with our original algorithm. In addition, the new algorithm allows discrimination of PSCs by composition in terms of their ensemble backscatter and depolarization in a manner analogous to that used in previous ground-based and airborne lidar PSC studies. Based on theoretical optical calculations, we define four CALIPSO-based composition classes which we call supercooled ternary solution (STS), ice, and Mix1 and Mix2, denoting mixtures of STS with nitric acid trihydrate (NAT) particles in lower or higher number densities/volumes, respectively. We examine the evolution of PSCs for three Antarctic and two Arctic seasons and illustrate the unique attributes of the CALIPSO PSC database. These analyses show substantial interannual variability in PSC areal coverage and also the well-known contrast between the Antarctic and Arctic. The CALIPSO data also reveal seasonal and altitudinal variations in Antarctic PSC composition, which are related to changes in HNO3 and H2O observed by the Microwave Limb Sounder on the Aura satellite.
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Kox, S., L. Bugliaro, and A. Ostler. "Retrieval of cirrus cloud optical thickness and top altitude from geostationary remote sensing." Atmospheric Measurement Techniques 7, no. 10 (October 1, 2014): 3233–46. http://dx.doi.org/10.5194/amt-7-3233-2014.
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Abstract. A novel approach for the detection of cirrus clouds and the retrieval of optical thickness and top altitude based on the measurements of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) aboard the geostationary Meteosat Second Generation (MSG) satellite is presented. Trained with 8 000 000 co-incident measurements of the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission the new "cirrus optical properties derived from CALIOP and SEVIRI algorithm during day and night" (COCS) algorithm utilizes a backpropagation neural network to provide accurate measurements of cirrus optical depth τ at λ = 532 nm and top altitude z every 15 min covering almost one-third of the Earth's atmosphere. The retrieved values are validated with independent measurements of CALIOP and the optical thickness derived by an airborne high spectral resolution lidar.