Periodic Reporting for period 2 - EGSIEM (European Gravity Service for Improved Emergency Management)
Reporting period: 2016-01-01 to 2017-12-31
Changes in continental water storage control the regional water budget and can, in extreme cases, result in floods and droughts that often claim a high toll on infrastructure, economy and human lives. EGSIEM has demonstrated that mass redistribution products open the door for innovative approaches to flood and drought monitoring and forecast. The timeliness and reliability of information is the primary concern for any early-warning system and EGSIEM has improved the temporal resolution from one month, to just one day, and to provide gravity field information within less than 5 days (near real-time). Early warning indications derived from these products are expected to improve the awareness of potentially evolving Hydrological extremes and have started to help in the scheduling of high-resolution follow-up satellite observations. EGSIEM has provided improved data and indicators for integration into the work of the Center for Satellite Based Crisis Information (ZKI, operated by the German Aerospace Center) and its use within international initiatives, such as the Copernicus Emergency Management Service and the International Charter "Space and Major Disasters".
To ensure robust performance of EGSIEM products they have been assessed with complementary data and post-processed mass products derived from the combined knowledge of the entire European GRACE community unified within our consortium.
The overall objectives for EGSIEM can be summarised as:
1) a scientific combination service
2) a near real-time service
3) and a hydrological/early warning service
Hydrological applications using GRACE data proved that it is possible to derive gravitational based wetness indicators that allow users to quantify catchment anomalies. However, reducing the latency from 60 to less than five days and increasing the temporal resolution to daily for a low degree Earth’s gravity field solution has been a prerequisite to establish a prototype monitoring service. The EGSIEM consortium realized this within the near-real time (NRT) objective. In terms of operational processing, the Analysis Centers at GFZ and TUG are now able to deliver daily global and regional gravity field solutions within less than the projected five days latency in a fully automated manner including computation, internal evaluation and distribution. For the operational test period the consortium successfully ran the service in real-time. In the run up to the NRT service operational test run, the whole GRACE time series from 2002 until 2017 was successfully processed. The resulting post-processing solutions of both GFZ and TUG are publicly available as gridded water storage products at the respective ftp servers, the service is currently on-hold due to the decommissioning of GRACE. The gravitational wetness index derived by the EGSIEM consortium enables users to monitor (sub-) surface hydrological mass variations in near-real time. The primary effort of this service was therefore the reliable and robust derivation of the wetness index from the products provided by the NRT.