Autoregressive Reconstruction of Total Water Storage within GRACE and GRACE Follow-On Gap Period

For 15 years, the Gravity Recovery and Climate Experiment (GRACE) mission have monitored total water storage (TWS) changes. The GRACE ended in October 2017, 11 months later, Follow-On (GRACE-FO) was launched May 2018. Bridging gap between both missions is essential to obtain continuous mass To fill gap, we propose a new approach based on remove–restore technique combined with an autoregressive (AR) prediction. We first make use of Global Land Data Assimilation System (GLDAS) hydrological model remove climatology from GRACE/GRACE-FO data. Since GLDAS mis-models real TWS changes for many regions around world, further least-squares estimation (LSE) remaining residual trends annual semi-annual oscillations. missing values are then predicted forward backward AR model. approach, before gap; GRACE-FO after gap. efficiency forward–backward prediction examined artificial that create July 2008 2009 period. average differences observed at maximum 5 cm 80% areas, extreme Amazon, Alaska, South Northern Asia. demonstrate better than standalone more 75% continental areas. natural (July 2017–May 2018), misclosures backward–forward estimated forward- backward-predicted equal 10 cm. This represents amount 10–20% signal 60% regional analysis shows presented method able capture occurrence droughts or floods, but does not reflect their magnitudes. Results indicate can be utilized reliably predict analysis, removed must properly matched selected region.