A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment （GRACE） K-Band Range Rate （KBRR） data based on dynamic integral approach is presented in this pa...A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment （GRACE） K-Band Range Rate （KBRR） data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combi- nation filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale fiver basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research （CSR）, GeoForschungsZentrum Potsdam （GFZ） and Jet Pro- pulsion Laboratory 0PL）. Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system （DEOS）, Tongji University （Tongji）, Institute of Theoretical Geodesy （ITG）, Astronomical Institute in University of Bern （AIUB） and Groupe de Recherche de Geodesie Spatiale （GRGS}, which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions.展开更多
It is important to quantify mass variations in the Antarctic ice sheet hybrid filtering scheme employing a combination of the decorrelated to study the global sea-level rise and climate change. A filter P3M6 and 300 k...It is important to quantify mass variations in the Antarctic ice sheet hybrid filtering scheme employing a combination of the decorrelated to study the global sea-level rise and climate change. A filter P3M6 and 300 km Fan filter was used, and the sur- face mass variations over the Antarctic are recovered from GRACE CSR RL04 monthly gravity field models from August 2002 to June 2010. After deduction of leakage errors using the GLDAS hydrological model and postglacial rebound effects using the glacial isostatic adjustment model IJ05, the variations in the ice sheet mass are obtained. The results reveal that the rate of melting of the Antarctic ice sheet is 80.0 Gt/a and increasing and contributes 0.22 mm/a to the global sea-level rise; the mass loss rate is 78.3 Gt/a in the West Antarctic and 1.6 Gt/a in the East Antarctic. The average mass loss rate increases from 39.3 Gt/a for the period 2002-2005 to 104.2 Gt/a for the period 2006-2010, and its corresponding contribution to the global sea-level rise increases from 0.11 to 0.29 mm/a, which indicates accelerated ice mass loss over the Antarctic since 2006. Moreover, the mass accumulation rates for Enderby Land and Wilkes Land along the coast of East Antarctica decrease for the period 2006-2008 but increase evidently after 2009.展开更多
The Gravity Recovery and Climate Experiment（GRACE） mission can significantly improve our knowledge of the temporal variability of the Earth＇s gravity field.We obtained monthly gravity field solutions based on varia...The Gravity Recovery and Climate Experiment（GRACE） mission can significantly improve our knowledge of the temporal variability of the Earth＇s gravity field.We obtained monthly gravity field solutions based on variational equations approach from GPS-derived positions of GRACE satellites and K-band range-rate measurements.The impact of different fixed data weighting ratios in temporal gravity field recovery while combining the two types of data was investigated for the purpose of deriving the best combined solution.The monthly gravity field solution obtained through above procedures was named as the Institute of Geodesy and Geophysics（IGG） temporal gravity field models.IGG temporal gravity field models were compared with GRACE Release05（RL05） products in following aspects：（i） the trend of the mass anomaly in China and its nearby regions within 2005-2010; （ii） the root mean squares of the global mass anomaly during 2005-2010; （iii） time-series changes in the mean water storage in the region of the Amazon Basin and the Sahara Desert between 2005 and 2010.The results showed that IGG solutions were almost consistent with GRACE RL05 products in above aspects（i）-（iii）.Changes in the annual amplitude of mean water storage in the Amazon Basin were 14.7 ± 1.2 cm for IGG,17.1 ± 1.3 cm for the Centre for Space Research（CSR）,16.4 ± 0.9 cm for the GeoForschungsZentrum（GFZ） and 16.9 ± 1.2 cm for the Jet Propulsion Laboratory（JPL） in terms of equivalent water height（EWH）,respectively.The root mean squares of the mean mass anomaly in Sahara were 1.2 cm,0.9 cm,0.9 cm and 1.2 cm for temporal gravity field models of IGG,CSR,GFZ and JPL,respectively.Comparison suggested that IGG temporal gravity field solutions were at the same accuracy level with the latest temporal gravity field solutions published by CSR,GFZ and JPL.展开更多
Since April 2002,the Gravity Recovery and Climate Experiment Satellite(GRACE)has provided monthly total water storage anomalies(TWSAs)on a global scale.However,these TWSAs are discontinuous because some GRACE observat...Since April 2002,the Gravity Recovery and Climate Experiment Satellite(GRACE)has provided monthly total water storage anomalies(TWSAs)on a global scale.However,these TWSAs are discontinuous because some GRACE observation data are missing.This study presents a combined machine learning-based modeling algorithm without hydrological model data.The TWSA time-series data for 11 large regions worldwide were divided into training and test sets.Autoregressive integrated moving average(ARIMA),long short-term memory(LSTM),and an ARIMA-LSTM combined model were used.The model predictions were compared with GRACE observations,and the model accuracy was evaluated using fi ve metrics:the Nash-Sutcliff e effi ciency coeffi cient(NSE),Pearson correlation coeffi cient(CC),root mean square error(RMSE),normalized RMSE(NRMSE),and mean absolute percentage error.The results show that at the basin scale,the mean CC,NSE,and NRMSE for the ARIMA-LSTM model were 0.93,0.83,and 0.12,respectively.At the grid scale,this study compared the spatial distribution and cumulative distribution function curves of the metrics in the Amazon and Volga River basins.The ARIMA-LSTM model had mean CC and NSE values of 0.89 and 0.61 and 0.92 and 0.61 in the Amazon and Volga River basins,respectively,which are superior to those of the ARIMA model(0.86 and 0.48 and 0.88 and 0.46,respectively)and the LSTM model(0.80 and 0.41 and 0.89 and 0.31,respectively).In the ARIMA-LSTM model,the proportions of grid cells with NSE>0.50 for the two basins were 63.3%and 80.8%,while they were 54.3%and 51.3%in the ARIMA model and 53.7%and 43.2%in the LSTM model.The ARIMA-LSTM model significantly improved the NSE values of the predictions while guaranteeing high CC values in the GRACE data reconstruction at both scales,which can aid in fi lling in discontinuous data in temporal gravity fi eld models..展开更多
Atmospheric de-aliasing is one of the most important background models for recovering Earth's temporal gravity field from gravity satellite missions.To meet the needs of China's gravimetric satellite platform,...Atmospheric de-aliasing is one of the most important background models for recovering Earth's temporal gravity field from gravity satellite missions.To meet the needs of China's gravimetric satellite platform,an independent atmospheric dealiasing model that relies on Chinese meteorological data needs to be developed.The release of CRA-40,as the firstgeneration Chinese atmospheric reanalysis,provides the opportunity.This study proposes a revised modeling method to calibrate CRA-40 and develops a new atmospheric de-aliasing model(HUST-CRA,2002-20).Intensive assessments are made between HUST-CRA and the latest official de-aliasing product of the international gravity satellite mission.The tidal components of the two products demonstrate high consistency,e.g.,the spatial correlation for the major tide S_1 is 0.96.The non-tidal components of the two products are also equivalent:(1)the temporal correlation of low-degree terms is higher than 0.97,except for the term of S22(0.93);(2)the spectral correlation of degree geoid height up to degree/order 100 is as high as 0.99;(3)the confidence interval of the spatial correlation(2002-20)is[0.971,0.995]at a confidence level of 95%;and(4)the difference in KBRR(K-band range rate)residuals is less than 0.08μm s^(-1),the difference in the derived temporal gravity field is less than 0.32 mm in terms of geoid height,and both are apparently beyond the ability of the current gravity satellite mission.This confirms that CRA-40 is of high quality and that the derived de-aliasing product,HUST-CRA,is accurate enough to be used in both Chinese and international gravity satellite missions.展开更多
The long-term continuous gravity observations obtained by the superconducting gravimeters(SG)at seven globally-distributed stations are comprehensively analyzed.After removing the signals related to the Earth's ti...The long-term continuous gravity observations obtained by the superconducting gravimeters(SG)at seven globally-distributed stations are comprehensively analyzed.After removing the signals related to the Earth's tides and variations in the Earth's rotation,the gravity residuals are used to describe the seasonal fluctuations in gravity field.Meanwhile,the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure,and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models.The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10-9 m s-2 in magnitude,and about 10×10-9 m s-2 for those due to the nontidal ocean loading in the coastal area.On the other hand,the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields,by using Gaussian smoothing technique in which the radius is set to be 600 km.Com-pared the land water induced gravity variations,the SG observations after removal of tides,polar mo-tion effects,air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other,it is inferred that both the ground-and space-based gravity observations can effec-tively detect the seasonal gravity variations with a magnitude of 100×10-9 m s-2 induced by the land water loading.This implies that high precision gravimetry is an effective technique to validate the re-liabilities of the hydrological models.展开更多
基金supported by the National 973Program of China(2013CB733302)the National Natural Science Foundation of China(41131067,41174020,41374023,41474019)+2 种基金the Open Research Fund Program of the State Key Laboratory of Geodesy and Earth's Dynamics(SKLGED2015-1-3-E)the open fund of State Key Laboratory of Geographic Information Engineering(SKLGIE2013-M-1-3)the open fund of Key Laboratory of Geospace Environment and Geodesy,Ministry of Education(13-02-05)
文摘A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment （GRACE） K-Band Range Rate （KBRR） data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combi- nation filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale fiver basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research （CSR）, GeoForschungsZentrum Potsdam （GFZ） and Jet Pro- pulsion Laboratory 0PL）. Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system （DEOS）, Tongji University （Tongji）, Institute of Theoretical Geodesy （ITG）, Astronomical Institute in University of Bern （AIUB） and Groupe de Recherche de Geodesie Spatiale （GRGS}, which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions.
基金supported by the National Basic Research Program of China (Grant No. 2007CB714405)the National Natural Science Foundation of China (Grant No. 40874002)the Program for New Century Excellent Talents in University (Grant No. NCET-07-0635)
文摘It is important to quantify mass variations in the Antarctic ice sheet hybrid filtering scheme employing a combination of the decorrelated to study the global sea-level rise and climate change. A filter P3M6 and 300 km Fan filter was used, and the sur- face mass variations over the Antarctic are recovered from GRACE CSR RL04 monthly gravity field models from August 2002 to June 2010. After deduction of leakage errors using the GLDAS hydrological model and postglacial rebound effects using the glacial isostatic adjustment model IJ05, the variations in the ice sheet mass are obtained. The results reveal that the rate of melting of the Antarctic ice sheet is 80.0 Gt/a and increasing and contributes 0.22 mm/a to the global sea-level rise; the mass loss rate is 78.3 Gt/a in the West Antarctic and 1.6 Gt/a in the East Antarctic. The average mass loss rate increases from 39.3 Gt/a for the period 2002-2005 to 104.2 Gt/a for the period 2006-2010, and its corresponding contribution to the global sea-level rise increases from 0.11 to 0.29 mm/a, which indicates accelerated ice mass loss over the Antarctic since 2006. Moreover, the mass accumulation rates for Enderby Land and Wilkes Land along the coast of East Antarctica decrease for the period 2006-2008 but increase evidently after 2009.
基金funded by the Major National Scientific Research Plan(2013CB733305,2012CB957703)the National Natural Science Foundation of China(41174066,41131067,41374087,41431070)
文摘The Gravity Recovery and Climate Experiment（GRACE） mission can significantly improve our knowledge of the temporal variability of the Earth＇s gravity field.We obtained monthly gravity field solutions based on variational equations approach from GPS-derived positions of GRACE satellites and K-band range-rate measurements.The impact of different fixed data weighting ratios in temporal gravity field recovery while combining the two types of data was investigated for the purpose of deriving the best combined solution.The monthly gravity field solution obtained through above procedures was named as the Institute of Geodesy and Geophysics（IGG） temporal gravity field models.IGG temporal gravity field models were compared with GRACE Release05（RL05） products in following aspects：（i） the trend of the mass anomaly in China and its nearby regions within 2005-2010; （ii） the root mean squares of the global mass anomaly during 2005-2010; （iii） time-series changes in the mean water storage in the region of the Amazon Basin and the Sahara Desert between 2005 and 2010.The results showed that IGG solutions were almost consistent with GRACE RL05 products in above aspects（i）-（iii）.Changes in the annual amplitude of mean water storage in the Amazon Basin were 14.7 ± 1.2 cm for IGG,17.1 ± 1.3 cm for the Centre for Space Research（CSR）,16.4 ± 0.9 cm for the GeoForschungsZentrum（GFZ） and 16.9 ± 1.2 cm for the Jet Propulsion Laboratory（JPL） in terms of equivalent water height（EWH）,respectively.The root mean squares of the mean mass anomaly in Sahara were 1.2 cm,0.9 cm,0.9 cm and 1.2 cm for temporal gravity field models of IGG,CSR,GFZ and JPL,respectively.Comparison suggested that IGG temporal gravity field solutions were at the same accuracy level with the latest temporal gravity field solutions published by CSR,GFZ and JPL.
基金financially supported by The National Natural Science Foundation of China (42374004)the Open Fund of Hubei Luojia Laboratory (220100045)the Natural Science Foundation of Sichuan Province (2022NSFSC1047)。
文摘Since April 2002,the Gravity Recovery and Climate Experiment Satellite(GRACE)has provided monthly total water storage anomalies(TWSAs)on a global scale.However,these TWSAs are discontinuous because some GRACE observation data are missing.This study presents a combined machine learning-based modeling algorithm without hydrological model data.The TWSA time-series data for 11 large regions worldwide were divided into training and test sets.Autoregressive integrated moving average(ARIMA),long short-term memory(LSTM),and an ARIMA-LSTM combined model were used.The model predictions were compared with GRACE observations,and the model accuracy was evaluated using fi ve metrics:the Nash-Sutcliff e effi ciency coeffi cient(NSE),Pearson correlation coeffi cient(CC),root mean square error(RMSE),normalized RMSE(NRMSE),and mean absolute percentage error.The results show that at the basin scale,the mean CC,NSE,and NRMSE for the ARIMA-LSTM model were 0.93,0.83,and 0.12,respectively.At the grid scale,this study compared the spatial distribution and cumulative distribution function curves of the metrics in the Amazon and Volga River basins.The ARIMA-LSTM model had mean CC and NSE values of 0.89 and 0.61 and 0.92 and 0.61 in the Amazon and Volga River basins,respectively,which are superior to those of the ARIMA model(0.86 and 0.48 and 0.88 and 0.46,respectively)and the LSTM model(0.80 and 0.41 and 0.89 and 0.31,respectively).In the ARIMA-LSTM model,the proportions of grid cells with NSE>0.50 for the two basins were 63.3%and 80.8%,while they were 54.3%and 51.3%in the ARIMA model and 53.7%and 43.2%in the LSTM model.The ARIMA-LSTM model significantly improved the NSE values of the predictions while guaranteeing high CC values in the GRACE data reconstruction at both scales,which can aid in fi lling in discontinuous data in temporal gravity fi eld models..
基金financial support from the National Natural Science Foundation of China(Grant Nos.42274112 and 41804016)supported by Danmarks Frie Forskningsfond[https://doi.org/10.46540/2035-00247B]through the DANSk-LSM project and HPC Platform of Huazhong University of Science and Technology。
文摘Atmospheric de-aliasing is one of the most important background models for recovering Earth's temporal gravity field from gravity satellite missions.To meet the needs of China's gravimetric satellite platform,an independent atmospheric dealiasing model that relies on Chinese meteorological data needs to be developed.The release of CRA-40,as the firstgeneration Chinese atmospheric reanalysis,provides the opportunity.This study proposes a revised modeling method to calibrate CRA-40 and develops a new atmospheric de-aliasing model(HUST-CRA,2002-20).Intensive assessments are made between HUST-CRA and the latest official de-aliasing product of the international gravity satellite mission.The tidal components of the two products demonstrate high consistency,e.g.,the spatial correlation for the major tide S_1 is 0.96.The non-tidal components of the two products are also equivalent:(1)the temporal correlation of low-degree terms is higher than 0.97,except for the term of S22(0.93);(2)the spectral correlation of degree geoid height up to degree/order 100 is as high as 0.99;(3)the confidence interval of the spatial correlation(2002-20)is[0.971,0.995]at a confidence level of 95%;and(4)the difference in KBRR(K-band range rate)residuals is less than 0.08μm s^(-1),the difference in the derived temporal gravity field is less than 0.32 mm in terms of geoid height,and both are apparently beyond the ability of the current gravity satellite mission.This confirms that CRA-40 is of high quality and that the derived de-aliasing product,HUST-CRA,is accurate enough to be used in both Chinese and international gravity satellite missions.
基金Supported by Knowledge Innovation of Chinese Academy of Sciences(Grant No.KZCX2-YW-133)National Natural Science Foundation of China(Grant Nos.40730316 and 40574034)Frontier Domain Item of Chinese Academy of Sciences
文摘The long-term continuous gravity observations obtained by the superconducting gravimeters(SG)at seven globally-distributed stations are comprehensively analyzed.After removing the signals related to the Earth's tides and variations in the Earth's rotation,the gravity residuals are used to describe the seasonal fluctuations in gravity field.Meanwhile,the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure,and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models.The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10-9 m s-2 in magnitude,and about 10×10-9 m s-2 for those due to the nontidal ocean loading in the coastal area.On the other hand,the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields,by using Gaussian smoothing technique in which the radius is set to be 600 km.Com-pared the land water induced gravity variations,the SG observations after removal of tides,polar mo-tion effects,air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other,it is inferred that both the ground-and space-based gravity observations can effec-tively detect the seasonal gravity variations with a magnitude of 100×10-9 m s-2 induced by the land water loading.This implies that high precision gravimetry is an effective technique to validate the re-liabilities of the hydrological models.
