Validation of satellite-based soil moisture retrievals from SMAP with in situ observation in the Simineh-Zarrineh (Bokan) Catchment, NW of Iran

Abstract

Soil moisture is an influential parameter in land surface hydrology and precise soil moisturedata that can help researcher to realize the climate changes and land-atmosphereinteractions. A initial struggle for the utilize of soil moisture data from satellite sensors istheir reliability. It is important to appraise the dependability of those data before they canbe regularly used at a global or local scale. In this study, the satellite soil moisture data wasevaluated from the Soil Moisture Active/Passive (SMAP) over Simineh-Zarrineh Catchmentin Bokan region, NW of Iran. A total of 287 soil samples as ground-based observations in thetime period of 03 April to 03 December 2017 were taken for SMAP data validation. Resultsshowed that the satellite data and in situ observation has a good correlation, with a meancorrelation (r) value of 0.63 in total. This correlation level showed that, commonly, theSMAP soil moisture products over Simineh-Zarrineh Catchment (Bokan) have great quality,and it would be valuable for versatile utilization, including monitoring of land surface,weather prediction, modeling of hydrological process, soil loess monitoring, and climatestudies. The results reveal that the remotely sensed data demonstrate the good correlationwith in situ observation across the dry land with mean correlation (r) values of 0.67throughout the time period. Particularly, SMAP soil moisture reveal a constant structure forobtain the spatial distribution of surface soil moisture. Additional researches are necessaryfor well realizing the SMAP data.