Abstract:
The land surface is a crucial part of the Earth system. In this talk, we will review the opportunities and limitations of the increasing number of available satellite data for land surface data assimilation in view of today’s needs to limit the harm of natural hazards, to predict energy availability and agricultural production, or to monitor climate variability. Thereafter, we will illustrate how such needs can be addressed via microwave-based data assimilation for soil moisture and snow updating.

Passive and active microwave-based observations from the SMOS, SMAP and Sentinel-1 missions can be used directly in assimilation systems, i.e. as radiances or backscatter values, or they can be converted to geophysical retrievals of land surface properties. The presentation will show recent examples of both pathways to estimate soil moisture and snow depth at different spatial scales and over various regions. More specifically, we will discuss the direct assimilation of (i) SMOS or SMAP microwave radiances to update soil moisture globally, and over peatlands specifically to estimate groundwater, (ii) Sentinel-1 microwave backscatter to correct for soil moisture and irrigation across test regions in Europe, and the retrieval assimilation of (iii) a recent Sentinel-1 snow depth product over the Alps, and (iv) the ESA CCI soil moisture product over Europe.