Validation of smos l3 and l4 soil moisture products in the remedhus (Spain) and cemaden (brazil) networks

Abstract

A B S T R A C T This work analyzes the quality of the soil moisture L3 (25 km) and L4 (1 km) products generated at the Barcelona Expert Center (BEC) in two sites located in distinct semi-arid regions, where measurement networks are installed: “Red de Estaciones de Medición de la Humedad del Suelo” (REMEDHUS), which is located in the central part of the Duero basin (Spain), and National Center for Monitoring and Early Warning of Natural Disasters (CEMADEN), at Northeast of the Brazil. REMEDHUS has been used as a calibration/validation site for SMOS and SMAP missions. It is a dense network covering 35 x 35 km2 and it has 22 stations. The CEMADEN network provides a database for the development of early warnings for natural disasters that occurs in Brazil, such as droughts and floods. It is a sparse network covering 1000 x 1000 km2 with more than 500 station. Results show good correspondence between SMOS L4 data and the in situ soil moisture data for REMEDHUS and CEMADEN networks. Correlations mean range from 0.3 to 0.8, and depend mainly on the station situation, soil type, and land cover on both Spain and Brazil networks. For the average data of both series, the correlation coefficient is higher than 0.6. Results show that the L4 product are better correlated than the L3 product, although L4 and L3 products are quite similar. This indicates that both products are ready for its operational use, with L4 providing a better representation of the soil moisture status at finer scales.