Operalization of ESA CCI Soil Moisture in the Copernicus Climate Change Service

Abstract

The surface soil moisture (SM) state impacts the sphere of human-nature interaction at different levels. It contributes to changing the frequency and extent of extreme atmospheric events such as heatwaves, and it affects the ecosystem state which anthropogenic activities depend on. SM is therefore recognized as an Essential Climate Variable (ECV). Its monitoring at scales from multi-decadal to near-real time (NRT) benefits study fields as diverse as agricultural crop yield forecasting, wildfires prediction or drought and flood risk management.

The European Commission’s Copernicus Climate Change Service (C3S) includes a soil moisture data set that is regularly updated to support timely decision making. The C3S SM product is freely made available through the Copernicus Climate Data Store with a global coverage at daily, 10-daily and monthly aggregation levels. It integrates multiple NRT data streams for this purpose: The Land Parameter Retrieval Model (LPRM; Owe et al., 2001) is used to derive SM from operational satellite radiometers (AMSR2, SMAP, SMOS and GPM). EumetSat HSAF produces a scatterometer based SSM product from ASCAT sensors (on board of Metop-A/B/C) with a short delay (HSAF, 2019). Using a modified version of the ESA CCI SM merging algorithm (Gruber et al., 2019), C3S SM can therefore provide an ACTIVE (scatterometric), PASSIVE (radiometric) and COMBINED product with a short delay of 10-20 days. The C3S SM algorithm is updated on an annual basis with the latest scientific improvements from ESA CCI SM. Products are validated with in-situ measurements from the International Soil Moisture Network (ISMN; Dorigo et al., 2021) and reanalysis reference data using the QA4SM online validation service. Assessment reports are distributed with the data sets.

Several derived services can greatly profit from the use of C3S SM due to its short update delay. One outstanding example is the detection and estimation of precipitation amounts at the regional scale as performed in the SM2RAIN project (led by Italy’s IRPI-CNR institute), with applications in drought and flood analysis and management. Similarly, the impact of climatic extremes on food security can be mitigated using the scientific knowledge basis provided by C3S SM, as demonstrated in the EarthFoodSecurity service. This presentation will cover the climate service provided with C3S SM, including the input data streams, the processing and distribution of the products and their quality assessment; the impact and external applications of the service will also be covered.

The development of the ESA CCI products has been supported by ESA’s Climate Change Initiative for Soil Moisture (Contract No. 4000104814/11/I-NB and 4000112226/14/I-NB) and the European Union’s FP7 EartH2Observe “Global Earth Observation for Integrated Water Resource Assessment” project (grant agreement number 331 603608). Funded by Copernicus Climate Change Service implemented by ECMWF through C3S 312a/b Lot 7/4 Soil Moisture service.