نتایج جستجو برای: the gravity recovery and climate experiment grace

تعداد نتایج: 21200198  

2005
Isabella Velicogna John Wahr Edward Hanna Philippe Huybrechts

[1] We use twenty-two monthly GRACE (Gravity Recovery and Climate Experiment) gravity fields to recover nonsecular mass change in Greenland. The results show large seasonal variability. We compare with modeled precipitation, evaporation, and runoff derived from ERA40 (the 40-year ECMWF Re-Analysis of the global atmosphere). The model’s seasonal amplitude is controlled by runoff and agrees reaso...

2006
Sean Swenson Pat J.-F. Yeh John Wahr James Famiglietti

[1] This study presents the first direct comparison of terrestrial water storage estimates from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to in situ hydrological observations. Monthly anomalies of total water storage derived from GRACE gravity fields are compared with combined soil moisture and groundwater measurements from a network of observing sites in Illinois. T...

2005
Isabella Velicogna John Wahr

[1] We use 22 monthly GRACE (Gravity Recovery and Climate Experiment) gravity fields to estimate the linear trend in Greenland ice mass during 2002–2004. We recover a decrease in total ice mass of 82 ± 28 km of ice per year, consistent with estimates from other techniques. Our uncertainty estimate is dominated by the effects of GRACE measurement errors and errors in our post glacial rebound (PG...

2008
Sean Swenson Don Chambers John Wahr

[1] In this study, we estimate a time series of geocenter anomalies from a combination of data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission and the output from oceanmodels. Amatrix equation is derived relating total geocenter variations to the GRACE coefficients of degrees two and higher and to the oceanic component of the degree one coefficients. We estimate the o...

2005
J. Wickert

CHAMP (CHAllenging Minisatellite Payload) and GRACE (Gravity Recovery And Climate Experiment) formed a satellite configuration for precise atmospheric sounding during the first activation of the GPS (Global Positioning System) radio occultation experiment aboard GRACE on 28 and 29 July 2004. 338 occultations were recorded aboard both satellites, providing globally distributed vertical profiles ...

2003

The first 111 days of preliminary data from GRACE were used to produce a map of the Earth’s gravity anomalies. A gravity anomaly map shows us how much the actual Earth’s gravity field departs from “normal” as defined by a simplified mathematical gravity model that assumes the Earth is perfectly smooth and featureless. In this grayscale representation, brighter areas represent positive gravity a...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید چمران اهواز - دانشکده مهندسی علوم آب 1393

drought is transient phenomenon , slow , repetitive and integral part of the climate of each region. drought begins with a substantial reduction in precipitation over the long-term average rainfall and over time, reduced soil moisture and surface and ground water resources will continue to decrease. this phenomenon is the most important in bakhtegan basin because of its importance in strategic ...

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