The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Shilong Piao - One of the best experts on this subject based on the ideXlab platform.
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analysis of slight precipitation in china during the past decades and its relationship with advanced very high Radiometric Resolution normalized difference vegetation index
International Journal of Climatology, 2018Co-Authors: Yves Balkanski, Thomas Gasser, Philippe Ciais, Feng Zhou, Shu Tao, Shushi Peng, Shilong Piao, Rong WangAbstract:Precipitation is one of the most important factors determining the occurrence of extreme hydro-meteorological events and water resource availability. Precipitation in different grades has diverse ecological effects, and slight precipitation (SP, defined as 0.1-1.0 mm/day) is the minimal level among them. In this study, we investigated SP trends from 1961 to 2013, as well as the relationship between SP and advanced very high Radiometric Resolution (AVHRR) normalized difference vegetation index (NDVI) in China during growing season from 1981 to 2006. The distributions and trends of SP were analysed by calculating the daily precipitation data. The average annual slight precipitation amount (SPA) and the number of slight precipitation days (SPD), derived from 839 monitoring stations in China, show a decreasing trend over the last five decades, which is in agreement with total precipitation (TP) but in different rates. When the trend was analysed seasonally, SP in most stations decreases significantly in September-October-November (SON) and June-July-August (JJA), and the largest decrease is found in SON. About 49.5 and 68.7% of monitoring stations show a decreasing trend in SON, in both SPA and SPD, whereas the trend is less popular in March-April-May Accepted manuscript. Li et al. 2018, International Journal of Climatology. https://doi.org/10.1002/joc.5763 page 2 (MAM, SPA: 19.7%, SPD: 41.4%) and December-January-February (JJF, SPA: 25.6%, SPD: 43.1%). Moreover, our analysis indicates that the decrease of SP is mainly due to the decrease of SPD as the median amount of daily SP was unchanged over the past five decades (close to 0.3 mm/day). Based on 26-year (1981-2006) semi-monthly AVHRR NDVI data and the records of SP data, the relationship between AVHRR NDVI and SP was also investigated. In regions with lower (<600 mm) TP, the correlation coefficients between NDVI and SP tend to be higher. These results highlight that SP has different effects than TP on vegetation growth. We also analysed time lag effects and concluded that the sensitivity of NDVI to SP for grass vegetation (the correlation coefficient is 0.327) is more noticeable than for trees (0.211) or shrubs (−0.058). The relationship between SP and NDVI also provides us new insights on the dependence of vegetation growth on meteorological factors.
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Analysis of slight precipitation in China during the past decades and its relationship with advanced very high Radiometric Resolution normalized difference vegetation index
International Journal of Climatology, 2018Co-Authors: Yves Balkanski, Thomas Gasser, Philippe Ciais, Feng Zhou, Shu Tao, Shushi Peng, Shilong PiaoAbstract:Precipitation is one of the most important factors determining the occurrence of extreme hydro-meteorological events and water resource availability. Precipitation in different grades has diverse ecological effects, and slight precipitation (SP, defined as 0.1-1.0 mm/day) is the minimal level among them. In this study, we investigated SP trends from 1961 to 2013, as well as the relationship between SP and advanced very high Radiometric Resolution (AVHRR) normalized difference vegetation index (NDVI) in China during growing season from 1981 to 2006. The distributions and trends of SP were analysed by calculating the daily precipitation data. The average annual slight precipitation amount (SPA) and the number of slight precipitation days (SPD), derived from 839 monitoring stations in China, show a decreasing trend over the last five decades, which is in agreement with total precipitation (TP) but in different rates. When the trend was analysed seasonally, SP in most stations decreases significantly in September-October-November (SON) and June-July-August (JJA), and the largest decrease is found in SON. About 49.5 and 68.7% of monitoring stations show a decreasing trend in SON, in both SPA and SPD, whereas the trend is less popular in March-April-May Accepted manuscript. Li et al. 2018, International Journal of Climatology. https://doi.org/10.1002/joc.5763 page 2 (MAM, SPA: 19.7%, SPD: 41.4%) and December-January-February (JJF, SPA: 25.6%, SPD: 43.1%). Moreover, our analysis indicates that the decrease of SP is mainly due to the decrease of SPD as the median amount of daily SP was unchanged over the past five decades (close to 0.3 mm/day). Based on 26-year (1981-2006) semi-monthly AVHRR NDVI data and the records of SP data, the relationship between AVHRR NDVI and SP was also investigated. In regions with lower (
Thomas Gasser - One of the best experts on this subject based on the ideXlab platform.
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analysis of slight precipitation in china during the past decades and its relationship with advanced very high Radiometric Resolution normalized difference vegetation index
International Journal of Climatology, 2018Co-Authors: Yves Balkanski, Thomas Gasser, Philippe Ciais, Feng Zhou, Shu Tao, Shushi Peng, Shilong Piao, Rong WangAbstract:Precipitation is one of the most important factors determining the occurrence of extreme hydro-meteorological events and water resource availability. Precipitation in different grades has diverse ecological effects, and slight precipitation (SP, defined as 0.1-1.0 mm/day) is the minimal level among them. In this study, we investigated SP trends from 1961 to 2013, as well as the relationship between SP and advanced very high Radiometric Resolution (AVHRR) normalized difference vegetation index (NDVI) in China during growing season from 1981 to 2006. The distributions and trends of SP were analysed by calculating the daily precipitation data. The average annual slight precipitation amount (SPA) and the number of slight precipitation days (SPD), derived from 839 monitoring stations in China, show a decreasing trend over the last five decades, which is in agreement with total precipitation (TP) but in different rates. When the trend was analysed seasonally, SP in most stations decreases significantly in September-October-November (SON) and June-July-August (JJA), and the largest decrease is found in SON. About 49.5 and 68.7% of monitoring stations show a decreasing trend in SON, in both SPA and SPD, whereas the trend is less popular in March-April-May Accepted manuscript. Li et al. 2018, International Journal of Climatology. https://doi.org/10.1002/joc.5763 page 2 (MAM, SPA: 19.7%, SPD: 41.4%) and December-January-February (JJF, SPA: 25.6%, SPD: 43.1%). Moreover, our analysis indicates that the decrease of SP is mainly due to the decrease of SPD as the median amount of daily SP was unchanged over the past five decades (close to 0.3 mm/day). Based on 26-year (1981-2006) semi-monthly AVHRR NDVI data and the records of SP data, the relationship between AVHRR NDVI and SP was also investigated. In regions with lower (<600 mm) TP, the correlation coefficients between NDVI and SP tend to be higher. These results highlight that SP has different effects than TP on vegetation growth. We also analysed time lag effects and concluded that the sensitivity of NDVI to SP for grass vegetation (the correlation coefficient is 0.327) is more noticeable than for trees (0.211) or shrubs (−0.058). The relationship between SP and NDVI also provides us new insights on the dependence of vegetation growth on meteorological factors.
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Analysis of slight precipitation in China during the past decades and its relationship with advanced very high Radiometric Resolution normalized difference vegetation index
International Journal of Climatology, 2018Co-Authors: Yves Balkanski, Thomas Gasser, Philippe Ciais, Feng Zhou, Shu Tao, Shushi Peng, Shilong PiaoAbstract:Precipitation is one of the most important factors determining the occurrence of extreme hydro-meteorological events and water resource availability. Precipitation in different grades has diverse ecological effects, and slight precipitation (SP, defined as 0.1-1.0 mm/day) is the minimal level among them. In this study, we investigated SP trends from 1961 to 2013, as well as the relationship between SP and advanced very high Radiometric Resolution (AVHRR) normalized difference vegetation index (NDVI) in China during growing season from 1981 to 2006. The distributions and trends of SP were analysed by calculating the daily precipitation data. The average annual slight precipitation amount (SPA) and the number of slight precipitation days (SPD), derived from 839 monitoring stations in China, show a decreasing trend over the last five decades, which is in agreement with total precipitation (TP) but in different rates. When the trend was analysed seasonally, SP in most stations decreases significantly in September-October-November (SON) and June-July-August (JJA), and the largest decrease is found in SON. About 49.5 and 68.7% of monitoring stations show a decreasing trend in SON, in both SPA and SPD, whereas the trend is less popular in March-April-May Accepted manuscript. Li et al. 2018, International Journal of Climatology. https://doi.org/10.1002/joc.5763 page 2 (MAM, SPA: 19.7%, SPD: 41.4%) and December-January-February (JJF, SPA: 25.6%, SPD: 43.1%). Moreover, our analysis indicates that the decrease of SP is mainly due to the decrease of SPD as the median amount of daily SP was unchanged over the past five decades (close to 0.3 mm/day). Based on 26-year (1981-2006) semi-monthly AVHRR NDVI data and the records of SP data, the relationship between AVHRR NDVI and SP was also investigated. In regions with lower (
Shushi Peng - One of the best experts on this subject based on the ideXlab platform.
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analysis of slight precipitation in china during the past decades and its relationship with advanced very high Radiometric Resolution normalized difference vegetation index
International Journal of Climatology, 2018Co-Authors: Yves Balkanski, Thomas Gasser, Philippe Ciais, Feng Zhou, Shu Tao, Shushi Peng, Shilong Piao, Rong WangAbstract:Precipitation is one of the most important factors determining the occurrence of extreme hydro-meteorological events and water resource availability. Precipitation in different grades has diverse ecological effects, and slight precipitation (SP, defined as 0.1-1.0 mm/day) is the minimal level among them. In this study, we investigated SP trends from 1961 to 2013, as well as the relationship between SP and advanced very high Radiometric Resolution (AVHRR) normalized difference vegetation index (NDVI) in China during growing season from 1981 to 2006. The distributions and trends of SP were analysed by calculating the daily precipitation data. The average annual slight precipitation amount (SPA) and the number of slight precipitation days (SPD), derived from 839 monitoring stations in China, show a decreasing trend over the last five decades, which is in agreement with total precipitation (TP) but in different rates. When the trend was analysed seasonally, SP in most stations decreases significantly in September-October-November (SON) and June-July-August (JJA), and the largest decrease is found in SON. About 49.5 and 68.7% of monitoring stations show a decreasing trend in SON, in both SPA and SPD, whereas the trend is less popular in March-April-May Accepted manuscript. Li et al. 2018, International Journal of Climatology. https://doi.org/10.1002/joc.5763 page 2 (MAM, SPA: 19.7%, SPD: 41.4%) and December-January-February (JJF, SPA: 25.6%, SPD: 43.1%). Moreover, our analysis indicates that the decrease of SP is mainly due to the decrease of SPD as the median amount of daily SP was unchanged over the past five decades (close to 0.3 mm/day). Based on 26-year (1981-2006) semi-monthly AVHRR NDVI data and the records of SP data, the relationship between AVHRR NDVI and SP was also investigated. In regions with lower (<600 mm) TP, the correlation coefficients between NDVI and SP tend to be higher. These results highlight that SP has different effects than TP on vegetation growth. We also analysed time lag effects and concluded that the sensitivity of NDVI to SP for grass vegetation (the correlation coefficient is 0.327) is more noticeable than for trees (0.211) or shrubs (−0.058). The relationship between SP and NDVI also provides us new insights on the dependence of vegetation growth on meteorological factors.
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Analysis of slight precipitation in China during the past decades and its relationship with advanced very high Radiometric Resolution normalized difference vegetation index
International Journal of Climatology, 2018Co-Authors: Yves Balkanski, Thomas Gasser, Philippe Ciais, Feng Zhou, Shu Tao, Shushi Peng, Shilong PiaoAbstract:Precipitation is one of the most important factors determining the occurrence of extreme hydro-meteorological events and water resource availability. Precipitation in different grades has diverse ecological effects, and slight precipitation (SP, defined as 0.1-1.0 mm/day) is the minimal level among them. In this study, we investigated SP trends from 1961 to 2013, as well as the relationship between SP and advanced very high Radiometric Resolution (AVHRR) normalized difference vegetation index (NDVI) in China during growing season from 1981 to 2006. The distributions and trends of SP were analysed by calculating the daily precipitation data. The average annual slight precipitation amount (SPA) and the number of slight precipitation days (SPD), derived from 839 monitoring stations in China, show a decreasing trend over the last five decades, which is in agreement with total precipitation (TP) but in different rates. When the trend was analysed seasonally, SP in most stations decreases significantly in September-October-November (SON) and June-July-August (JJA), and the largest decrease is found in SON. About 49.5 and 68.7% of monitoring stations show a decreasing trend in SON, in both SPA and SPD, whereas the trend is less popular in March-April-May Accepted manuscript. Li et al. 2018, International Journal of Climatology. https://doi.org/10.1002/joc.5763 page 2 (MAM, SPA: 19.7%, SPD: 41.4%) and December-January-February (JJF, SPA: 25.6%, SPD: 43.1%). Moreover, our analysis indicates that the decrease of SP is mainly due to the decrease of SPD as the median amount of daily SP was unchanged over the past five decades (close to 0.3 mm/day). Based on 26-year (1981-2006) semi-monthly AVHRR NDVI data and the records of SP data, the relationship between AVHRR NDVI and SP was also investigated. In regions with lower (
Josef Mittermayer - One of the best experts on this subject based on the ideXlab platform.
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Wrapped Staring Spotlight SAR
IEEE Transactions on Geoscience and Remote Sensing, 2016Co-Authors: Josef Mittermayer, Thomas Krauß, Paco Lopez-dekker, Pau Prats-iraola, Gerhard Krieger, Alberto MoreiraAbstract:This paper proposes the wrapped staring spotlight\ud (WSS) SAR imaging mode, which is a new method to extend\ud the azimuth steering capability for phased array SAR to achieve\ud either an improved azimuth geometric or Radiometric Resolution.\ud It investigates the utility of steering directions with main lobe gains\ud that are smaller than that of the grating lobes and exposes how\ud these directions can be exploited. Furthermore, two methods are\ud proposed to reduce the speckle and the image noise at once, i.e.,\ud the Look-Normalized Pattern Correction and the Ω-weighting.\ud Based on two example TerraSAR-X WSS acquisitions, the image\ud performance of extended and point targets is discussed
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TerraSAR-X System Performance Characterization and Verification
IEEE Transactions on Geoscience and Remote Sensing, 2010Co-Authors: Josef Mittermayer, Marwan Younis, R. Metzig, Steffen Wollstadt, J.m. Martinez, Adriano MetaAbstract:This paper presents results from the synthetic aperture radar (SAR) system performance characterization, optimization, and verification as carried out during the TerraSAR-X commissioning phase. Starting from the acquisition geometry and instrument performance, fundamental acquisition parameters such as elevation beam definition, range timing, receiving gain, and block adaptive quantization setting are presented. The verification of the key performance parameters-ambiguities, impulse-response function, noise, and Radiometric Resolution-is discussed. ScanSAR and Spotlight particularities are described.
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Radiometric Resolution optimization for future sar systems
International Geoscience and Remote Sensing Symposium, 2004Co-Authors: J Marquezmartinez, Josef Mittermayer, M RodriguezcassolaAbstract:This paper presents a Radiometric Resolution optimization strategy which can be used in new generation of Synthetic Aperture Radar (SAR) systems. An expression, which allows optimization depending on application, has been developed for this purpose. In particular, special effort has been made for improving the Radiometric Resolution keeping the geometric Resolution constant. Optimization examples have been carried out with realistic parameters taken from TerraSAR-X. The objective is to provide an effective and realistic way to tradeoff the instrument parameters for optimal exploitation of SAR images. Furthermore, a precise SNR formulation has been derived including processing gain and noise distribution
N Duffo - One of the best experts on this subject based on the ideXlab platform.
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angular and Radiometric Resolution of y shaped nonuniform synthetic aperture radiometers for earth observation
IEEE Geoscience and Remote Sensing Letters, 2008Co-Authors: A. Camps, M Vallllossera, I Corbella, F Torres, N DuffoAbstract:MIRAS is the single payload of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite mission, and it will be the first synthetic aperture radiometer for Earth observation from space. It consists of an array of 69 antennas uniformly spaced along three arms forming a Y-shaped antenna array. This work analyzes the angular Resolution improvement, and the Radiometric performance degradation when the spacing between antennas is geometrically increased.
