Continuity of terrestrial water storage variability and trends across mainland China monitored by the GRACE and GRACE-Follow on satellites

Terrestrial water storage (TWS) plays an important role in the global cycle. Measuring dynamic changes TWS is essential for resources management, weather-related hazard monitoring and agricultural production. The Gravity Recovery Climate Experiment (GRACE) its following mission (GRACE-Follow on) have provided monthly terrestrial anomalies (TWSA) at a quasi-global scale since April 2002. This study bridges data gap between two generations of satellites using Random Forest (RF), Support Vector Machine (SVM) Artificial Neural Network models over mainland China. We systematically examine spatiotemporal continuity GRACE GRACE-Follow on missions based spherical harmonics (SH) mass concentration blocks (mascons) solutions as well GLDAS-Noah across China during 2002–2020. Results show that CSR SH/CSR mascons reduces uncertainty TWSA from 5.26/6.96 to 3.83/4.65 mm/month, respectively. ML-predicted fits with in-situ observations satellites. Modeled also shows During period 2002–2020, reconstructed significantly decreased ? 0.03 mm/a 1.06 (p < 0.05) spatial heterogeneity whole In many areas China, increased rapidly range 5–15 0.05), while north southwest experienced decrease 5 25 0.05). provides bridged reveals variability which may contribute better understanding climate change management.