Making Sense of SMOS Soil Moisture Observations over Norway and Northern Areas, 2012

This project concerned studies to make more sense of the European Space Agency, ESA, SMOS (Soil Moisture and Ocean Salinity) soil moisture observations over Norway and Northern Areas. The SMOS satellite was launched in 2009 and is still working, providing data with relatively coarse spatial resolution (~43 km footprint), a limited instantaneous field of view (~1000 km across) and relatively infrequent revisits (1-3 days). The project used data assimilation ideas to improve the spatial and temporal information provided by SMOS to be more in line with user needs, i.e., offer higher rate, higher resolution, wider area “snap shot” information. For the data assimilation we used a variant of the Ensemble Kalman Filter (EnKF). The enhanced spatial resolution varied between 4 and 9 km (depending on model resolution) and the enhanced temporal resolution typically was 6 hours (the time step to update the analysis using SMOS data). As part of this study, the project evaluated the quality of satellite soil moisture observations and land surface model simulations over Norway, and assessed the NILU land data assimilation system in the context of studies of the hydrological cycle over land. This study addressed the challenge of using SMOS data to understand the hydrological cycle in Norway and Northern Areas, regions characterized by complex orography.