Preliminary evaluation of ASCAT-SWI and SMOS SM soil moisture products against in-situ observations in the Brazilian Caatinga biome

Franklin Javier Paredes, Humberto Barbosa, Kallianna Araujo, Geovânia dos Santos


In recent years, there has been increasing interest in remote sensing the temporal dynamics of soil moisture contents in large agricultural areas, such as those located in the Cattinga biome of the Northeast Brazil (NEB). In this context, validation is critical for accurate and credible satellite-based products usage. The aim of this work is to present the results of the quality assessment of the Surface Soil Moisture (SSM) estimates derived from the microwave sensors on board of the Soil Moisture and Ocean Salinity (SMOS) satellite and the METOP satellite series. Dataset for both platforms are disseminated through the SMOS SSM and ASCAT-SWI operational products, respectively. SMOS SMM and ASCAT-SWI time series were compared to in situ SSM data taken in two sites from the Alagoan semiarid where the Caatinga biome is dominant from February 2012 to October 2013 at a bimonthly time scale. The Spearman’s rho (r), Bias, and Root Mean Square Error (RMSE) were used as statistical metrics. Results revealed a poor performance for both products, but the SWI showed relatively good agreement in terms of trend when the soil moisture content in the upper layers was near to zero because of severe drought conditions. SWI could be useful for monitoring the variation of the SSM in rainfed crop areas of the Caatinga biome affected by severe droughts.


surface soil moisture; SMOS; ASCAT SWI; Caatinga; Northeast Brazil

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