Abstract
Accurate terrestrial water storage (TWS) estimation is important to evaluate the situation of the water resources over the Yangtze River Basin (YRB). This study exploits the TWS observation from the new temporal gravity field model, HUST-Grace2016 (Huazhong University of Science and Technology), which is developed by a new low-frequency noise processing strategy. A novel GRACE (Gravity Recovery and Climate Experiment) post-processing approach is proposed to enhance the quality of the TWS estimate, and the improved TWS is used to characterize the drought and flood events over the YRB. The HUST-Grace2016-derived TWS presents good agreement with the CSR (Center for Space Research) mascon solution as well as the PCR-GLOBWB (PCRaster Global Water Balance) hydrological model. Particularly, our solution provides remarkable performance in identifying the extreme climate events e.g., flood and drought over the YRB and its sub-basins. The comparison between GRACE-derived TWS variations and the MODIS-derived (Moderate Resolution Imaging Spectroradiometer) inundated area variations is then conducted. The analysis demonstrates that the terrestrial reflectance data can provide an alternative way of cross-comparing and validating TWS information in Poyang Lake and Dongting Lake, with a correlation coefficient of 0.77 and 0.70, respectively. In contrast, the correlation is only 0.10 for Tai Lake, indicating the limitation of cross-comparison between MODIS and GRACE data. In addition, for the first time, the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) vertical velocity data is incorporated with GRACE TWS in the exploration of the climate-induced hydrological activities. The good agreement between non-seasonal NCEP/NCAR vertical velocities and non-seasonal GRACE TWSs is found in flood years (2005, 2010, 2012 and 2016) and drought years (2006, 2011 and 2013). The evidence shown in this study may contribute to the analysis of the mechanism of climate impacts on the YRB.
Highlights
The Yangtze River Basin (YRB), with a total drainage area of approximately 1.8 million km2, serves as the primary fresh water resource for more than 400 million people in China
Since 2002, terrestrial water storage (TWS) variations derived from the Gravity Recovery and Climate Experiment (GRACE) mission have been widely used to identify the extreme hydrological activities over large-scale regions
The Release 05 (RL05) models provided by Center for Space Research (CSR) [9], GeoForschungsZentrum (GFZ) [10] and the Jet Propulsion Laboratory (JPL) [11]
Summary
The Yangtze River Basin (YRB), with a total drainage area of approximately 1.8 million km, serves as the primary fresh water resource for more than 400 million people in China. In this study, incorporated with our own GRACE model, the vertical velocity data over the YRB was used to build a direct connection with GRACE-derived TWS This may be helpful in investigating climate-induced hydrological activities over the YRB. The forward-modeling method was implemented as follows: (1) the input was the ‘filtered reference TWS’, which was computed by applying a 300 km Gaussian filter and a P3M6 de-correlation filter; it was set as ‘candidate TWS’ in the first iteration; (2) the ‘candidate TWS’ was assigned uniformly over the ocean It was the opposite value of the mean TWS over land. The linear trends of the GRACE-derived TWS time series were removed
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