ESA CCI and C3S Soil Moisture - New developments and recent applications

Abstract

ESA CCI Soil Moisture (SM) is a long-term global Climate Data Record of soil water content stored in the surface soil layer, derived from satellite observations in the microwave domain. To make it suitable for long-term analyses of the climate system, ESA CCI SM merges observations from a total of 19 satellite radiometers and scatterometers (active and passive systems) into harmonized records covering a period of more than 40 years (from 1978 onwards). ESA CCI SM is currently in its 8th development cycle. Following every development cycle, the CCI algorithm is adopted to create the Copernicus Climate Change (C3S) soil moisture data records. These operational records are extended on a regular basis to provide input data for time-critical applications such as monitoring systems.

The data sets have been widely used (100+ scientific publications per year) in studying the water, energy and carbon cycles over land, understanding land surface-atmosphere hydrological feedbacks, assessing the impact of climate change on the occurrence of climatic extremes, assimilation into and evaluation of climate models. ESA CCI SM has been the main input for assessing global soil moisture conditions as presented in the BAMS “State of the Climate” reports for more than 10 years, while C3S has been used in the yearly “European State of the Climate” reports for several years now

In this presentation we give an overview over the algorithm underlying the ESA CCI SM product with a focus on new scientific developments included in the latest version. These comprise an improvement in the estimation of intra-annual uncertainties and two additional, experimental versions of the COMBINED product: 1) a gap-filled version in which data points between satellite overpasses are interpolated using statistical methods without the use of ancillary data; and 2) a model-independent version in which all merged sensors are scaled to L-band observations, as opposed to model values in previous versions. We show how both ESA CCI and C3S have been used in recent years to monitor droughts and floods globally and in Europe, respectively.