A review of the applications of ASCAT [ Advanced SCATterometer] soil moisture products

Remote sensing of soil moisture has reached a level of good maturity and accuracy for which the retrieved products are ready to use in real-world applications. Due to the importance of soil moisture in the partitioning of the water and energy uxes between the land surface and the atmosphere, a wide range of applicationscanbene tfromtheavailabilityofsatellitesoilmoisture products. Speci cally, the Advanced SCATterometer (ASCAT) on boardtheseriesofMeteorologicalOperational(Metop)satellitesis providing a near real time (and long-term, 9+ years starting from January2007)soilmoistureproduct,withanearlydaily(sub-daily after the launch of Metop-B) revisit time and a spatial sampling of 12.5 and 25 km. This study rst performs a review of the climatic, meteorological,andhydrologicalstudiesthatusesatellitesoilmoisture products for a better understanding of the water and energy cycle. Speci cally, applications that consider satellite soil moistureproductforimprovingtheirpredictionsareanalyzed anddiscussed. Moreover, four real examples are shown in which ASCAT soil moisture observations have been successfully applied toward: 1) numerical weather prediction, 2) rainfall estimation, 3) ood forecasting,and4)droughtmonitoringandprediction.Finally,the strengthsandlimitationsofASCATsoilmoistureproductsandthe way forward for fully exploiting these data in real-world applications are discussed.