Toward near-real time analysis of gravity change with the examples of flood and flash drought events

We discuss a methodology of scientifically utilizing high-precision laser ranging measurements (in addition to K-band microwave) for higher temporal sampling of surface mass changes.  The standard spatial analysis (i.e., global gravity field recovery) over a month period such as L2 and L3 data processing would produce a biased estimate when characteristic time scales of mass change processes are shorter than a month.  Our proposed time-domain (along-track) analysis will lead to better quantification of such processes.  Furthermore, we exploit the low-latency (within 1–3 days) Quick-Look (QL) L1B data to examine the feasibility of immediate assessment of extreme events such as flood and flash drought.  Such QL data processing can promote timely assessment of severe weather events and natural hazards as important applications of the GRACE-FO mission.  As examples, we present the data processing results for the 2019 South East US flash drought, the 2020 (unusually large) monsoonal flood in Bangladesh, and the 2021 Eastern Australia flood.  A new streamlined along-track data processing chain is proposed to facilitate utilization of superb laser ranging measurements for advanced quantification of rapid Earth system changes we experience recent years.