Continental water storage plays a major role in Earth's climate system.However,temporal and spatial variations of continental water are poorly known,particularly in Africa.Gravity Recovery and Climate Experiment(G...Continental water storage plays a major role in Earth's climate system.However,temporal and spatial variations of continental water are poorly known,particularly in Africa.Gravity Recovery and Climate Experiment(GRACE)satellite mission provides an opportunity to estimate terrestrial water storage(TWS)variations at both continental and river-basin scales.In this paper,seasonal and secular variations of TWS within Africa for the period from January 2003 to July 2013 are assessed using monthly GRACE coefficients from three processing centers(Centre for Space Research,the German Research Centre for Geo-sciences,and NASA's Jet Propulsion Laboratory).Monthly grids from Global Land Data Assimilation System(GLDAS)-I and from the Tropical Rainfall Measuring Mission(TRMM)-3B43 models are also used in order to understand the reasons of increasing or decreasing water storage.Results from GRACE processing centers show similar TWS estimates at seasonal timescales with some differences concerning inter-annual trend variations.The largest annual signals of GRACE TWS are observed in Zambezi and Okavango River basins and in Volta River Basin.An increasing trend of 11.60 mm/a is found in Zambezi River Basin and of 9 mm/a in Volta River Basin.A phase shift is found between rainfall and GRACE TWS GRACE TWS is preceded by rainfall by 2-3 months in parts of south central Africa.Comparing GLDAS rainfall with TRMM model,it is found that GLDAS has a dry bias from TRMM model.展开更多
Regional sea level variability is linked to regional terrestrial water and the El Ni?o-Southern Oscillation(ENSO).This study assessed the relationships between the sea level variations in the South China Sea(SCS)and E...Regional sea level variability is linked to regional terrestrial water and the El Ni?o-Southern Oscillation(ENSO).This study assessed the relationships between the sea level variations in the South China Sea(SCS)and ENSO,the impact of terrestrial water storage(TWS)on non-steric sea level(NSSL),and the contributions of steric sea level(SSL)and NSSL to sea level anomaly(SLA),respectively.From 2003 to 2015,the SLAs exhibited a long-term trend of 6.65±0.78 mm/yr,which was primarily attributed to the SSLs.Additionally,during 2003-2015,ENSO events alternating with varying intensities might also be responsible for the unusually high SLA trend.Compared to the SSLs,the NSSLs contributed the seasonal signals to the SLAs,while the NSSLs changes were largely explained by the TWS in the Mekong River Basin at the seasonal scale and in the Pearl River Basin and Red River Basin at other time scales.In contrast to the TWS,the contributions of precipitation and evapotranspiration were relatively minor.A negative correlation between the sea level variations and ENSO was also found,with cross-correlation coefficients between the oceanic Ni?o index and SLAs/SSLs/NSSLs of -0.36/-0.37/-0.62 with lags of 2/3/2 months,respectively.These findings systematically reassessed the contributions of different components to the sea level variations.This study provided a benchmark for in-depth analysis of the impacts of terrestrial water and other potential causes on sea level rise in the SCS.展开更多
In the past few decades,the irrational use of water resources has resulted in many issues such as land subsidence in the North China Plain(NCP),hindering its socio-economic development.An accurate understanding of wat...In the past few decades,the irrational use of water resources has resulted in many issues such as land subsidence in the North China Plain(NCP),hindering its socio-economic development.An accurate understanding of water resource changes is important for the allocation of water resources in the NCP.In this study,we employed Gravity Recovery and Climate Experiment(GRACE) satellite data to monitor the total water storage(TWS) change in the NCP during 2004–2019.Evapotranspiration,precipitation,and runoff during 2004–2019 were sequentially examined,using the water balance formula(WBF),to retrieve TWS change.Furthermore,the soil moisture,snow water equivalent,and canopy water storage from the Global Land Data Assimilation System were used to calculate the natural component of the TWS variations.A comparison of these results revealed the drivers of the changes in water resources.The results showed that:(1) overall TWS retrieved by GRACE decreased substantially as a consequence of human activity,while TWS obtained by WBF fluctuated periodically around zero under the impact of three natural drivers;(2) TWS in the NCP fell at a remarkable rate of-12.39 mm/y from 2004 to 2019,and the natural part of TWS experienced two significant declines,during 2004–2010 and 2013–2016;(3) variations in runoff,precipitation,and evapotranspiration from 2004 to 2019 were not significant,but human activities contributed more to the decreasing TWS than natural factors.This study provides a reference for water resource management and groundwater exploitation across the NCP under climate change.展开更多
To meet the growing demand for socioeconomic development,a large amount of groundwater is extracted from confined aquifers worldwide.The North China Plain has experienced considerable groundwater depletion and subside...To meet the growing demand for socioeconomic development,a large amount of groundwater is extracted from confined aquifers worldwide.The North China Plain has experienced considerable groundwater depletion and subsidence during the past six decades.In this study,we use Sentinel-1A/B SAR images from 2015 to 2020 to map the ground subsidence of the Tianjin–Langfang area.Three subsiding zones centered at Guangyang,Wuqing–Bazhou,and Jinghai are identified with maximum subsidence rates of 98.1,121.8,and 104.7 mm/yr.Seasonal and long-term signals are separated from time series subsidence and hydraulic measurements using continuous wavelet transform to retrieve aquifer parameters.The long-term subsidence,which fits well with an exponential decaying model,remarkably slows down in our study area.The elastic skeletal storage coefficients range between 0.52×10−3 and 9.66×10−3.We then retrieve the spatial–temporal variations of total groundwater storage,recoverable groundwater storage,and irreversible groundwater storage.Groundwater storage depletion rates are apparently reducing,which benefits from the operation of the South-to-North Water Transfer Project and local groundwater management practices.展开更多
为了更全面地分析区域陆地水储量长期变化趋势,利用2002年4月—2017年6月近16年的重力恢复与气候实验(gravity recovey and climate explorer,GRACE)时变重力场数据反演中国大陆地区陆地水储量变化,并与全球陆地资料同化系统(global lan...为了更全面地分析区域陆地水储量长期变化趋势,利用2002年4月—2017年6月近16年的重力恢复与气候实验(gravity recovey and climate explorer,GRACE)时变重力场数据反演中国大陆地区陆地水储量变化,并与全球陆地资料同化系统(global land data assimilation system,GLDAS)水文模型结果进行比较分析。同时,通过扣除季节性信号研究近16年来中国大陆地区陆地水储量的异常变化。研究结果表明:在2002—2017年间,中国大陆地区北方以减少为主,而南方以增加为主,其中青藏高原南部、新疆北部和华北地区减少趋势最为显著,并呈现出加速趋势。GRACE时变重力场和GLDAS模型得到的关于加速度项时空分布基本相符,加速度项与长期趋势项的结合更好地反演区域陆地水储量变化。展开更多
基金supported by the Main Direction Project of Chinese Academy of Sciences(KJCX2-EW-T03)Shanghai Science and Technology Commission Project(12DZ2273300)National Natural Science Foundation of China(NSFC)Project(11173050 and 11373059)
文摘Continental water storage plays a major role in Earth's climate system.However,temporal and spatial variations of continental water are poorly known,particularly in Africa.Gravity Recovery and Climate Experiment(GRACE)satellite mission provides an opportunity to estimate terrestrial water storage(TWS)variations at both continental and river-basin scales.In this paper,seasonal and secular variations of TWS within Africa for the period from January 2003 to July 2013 are assessed using monthly GRACE coefficients from three processing centers(Centre for Space Research,the German Research Centre for Geo-sciences,and NASA's Jet Propulsion Laboratory).Monthly grids from Global Land Data Assimilation System(GLDAS)-I and from the Tropical Rainfall Measuring Mission(TRMM)-3B43 models are also used in order to understand the reasons of increasing or decreasing water storage.Results from GRACE processing centers show similar TWS estimates at seasonal timescales with some differences concerning inter-annual trend variations.The largest annual signals of GRACE TWS are observed in Zambezi and Okavango River basins and in Volta River Basin.An increasing trend of 11.60 mm/a is found in Zambezi River Basin and of 9 mm/a in Volta River Basin.A phase shift is found between rainfall and GRACE TWS GRACE TWS is preceded by rainfall by 2-3 months in parts of south central Africa.Comparing GLDAS rainfall with TRMM model,it is found that GLDAS has a dry bias from TRMM model.
基金supported by the Natural Science Foundation of Hubei Province,China(Grant No.2022CFB064)the National Natural Science Foundation of China(Grant Nos.41974003&41674007)。
文摘Regional sea level variability is linked to regional terrestrial water and the El Ni?o-Southern Oscillation(ENSO).This study assessed the relationships between the sea level variations in the South China Sea(SCS)and ENSO,the impact of terrestrial water storage(TWS)on non-steric sea level(NSSL),and the contributions of steric sea level(SSL)and NSSL to sea level anomaly(SLA),respectively.From 2003 to 2015,the SLAs exhibited a long-term trend of 6.65±0.78 mm/yr,which was primarily attributed to the SSLs.Additionally,during 2003-2015,ENSO events alternating with varying intensities might also be responsible for the unusually high SLA trend.Compared to the SSLs,the NSSLs contributed the seasonal signals to the SLAs,while the NSSLs changes were largely explained by the TWS in the Mekong River Basin at the seasonal scale and in the Pearl River Basin and Red River Basin at other time scales.In contrast to the TWS,the contributions of precipitation and evapotranspiration were relatively minor.A negative correlation between the sea level variations and ENSO was also found,with cross-correlation coefficients between the oceanic Ni?o index and SLAs/SSLs/NSSLs of -0.36/-0.37/-0.62 with lags of 2/3/2 months,respectively.These findings systematically reassessed the contributions of different components to the sea level variations.This study provided a benchmark for in-depth analysis of the impacts of terrestrial water and other potential causes on sea level rise in the SCS.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFF0711603)the Fundamental Research Funds for the Central Universities (Grant Nos.0209-14380093 and0209-14380097)+2 种基金the Frontiers Science Center for Critical Earth Material Cycling Fund (Grant No.JBGS2102)the National Natural Science Foundation of China (Grant No.41671423)the Ministry Science and Technology Development of China-Data Sharing Infrastructure of Earth System Science (Grant No.2005DKA32300)。
文摘In the past few decades,the irrational use of water resources has resulted in many issues such as land subsidence in the North China Plain(NCP),hindering its socio-economic development.An accurate understanding of water resource changes is important for the allocation of water resources in the NCP.In this study,we employed Gravity Recovery and Climate Experiment(GRACE) satellite data to monitor the total water storage(TWS) change in the NCP during 2004–2019.Evapotranspiration,precipitation,and runoff during 2004–2019 were sequentially examined,using the water balance formula(WBF),to retrieve TWS change.Furthermore,the soil moisture,snow water equivalent,and canopy water storage from the Global Land Data Assimilation System were used to calculate the natural component of the TWS variations.A comparison of these results revealed the drivers of the changes in water resources.The results showed that:(1) overall TWS retrieved by GRACE decreased substantially as a consequence of human activity,while TWS obtained by WBF fluctuated periodically around zero under the impact of three natural drivers;(2) TWS in the NCP fell at a remarkable rate of-12.39 mm/y from 2004 to 2019,and the natural part of TWS experienced two significant declines,during 2004–2010 and 2013–2016;(3) variations in runoff,precipitation,and evapotranspiration from 2004 to 2019 were not significant,but human activities contributed more to the decreasing TWS than natural factors.This study provides a reference for water resource management and groundwater exploitation across the NCP under climate change.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41702376,42001368 and 42174043).
文摘To meet the growing demand for socioeconomic development,a large amount of groundwater is extracted from confined aquifers worldwide.The North China Plain has experienced considerable groundwater depletion and subsidence during the past six decades.In this study,we use Sentinel-1A/B SAR images from 2015 to 2020 to map the ground subsidence of the Tianjin–Langfang area.Three subsiding zones centered at Guangyang,Wuqing–Bazhou,and Jinghai are identified with maximum subsidence rates of 98.1,121.8,and 104.7 mm/yr.Seasonal and long-term signals are separated from time series subsidence and hydraulic measurements using continuous wavelet transform to retrieve aquifer parameters.The long-term subsidence,which fits well with an exponential decaying model,remarkably slows down in our study area.The elastic skeletal storage coefficients range between 0.52×10−3 and 9.66×10−3.We then retrieve the spatial–temporal variations of total groundwater storage,recoverable groundwater storage,and irreversible groundwater storage.Groundwater storage depletion rates are apparently reducing,which benefits from the operation of the South-to-North Water Transfer Project and local groundwater management practices.
文摘为了更全面地分析区域陆地水储量长期变化趋势,利用2002年4月—2017年6月近16年的重力恢复与气候实验(gravity recovey and climate explorer,GRACE)时变重力场数据反演中国大陆地区陆地水储量变化,并与全球陆地资料同化系统(global land data assimilation system,GLDAS)水文模型结果进行比较分析。同时,通过扣除季节性信号研究近16年来中国大陆地区陆地水储量的异常变化。研究结果表明:在2002—2017年间,中国大陆地区北方以减少为主,而南方以增加为主,其中青藏高原南部、新疆北部和华北地区减少趋势最为显著,并呈现出加速趋势。GRACE时变重力场和GLDAS模型得到的关于加速度项时空分布基本相符,加速度项与长期趋势项的结合更好地反演区域陆地水储量变化。
