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Abstract.

Soil moisture plays a critical role in water, food, and energy security. When ground-based observations are limited or unavailable, remotely-sensed data may provide useful information for diverse applications. Among all remotely-sensed mission, the NASA Soil Moisture Active Passive (SMAP) mission with the ability of radio frequency interference mitigation, was selected to be evaluated against ground-based observations over the contiguous United States. SMAP Level 4 with the 9-km resolution provided 3-hourly dataset on a global scale. Spatial and temporal analysis of SMAP L4 against ground-based data was conducted by applying statistical indicators including correlation, bias, RMSE, and ubRMSE. Results showed satisfying results from all statistical indicators which were more acceptable during winter compared to other seasons. Analysis of the impact of land use on the accuracy of soil moisture retrievals suggested lower accuracy of soil moisture estimates in intense vegetated areas. The results of this paper suggest SMAP L4 soil moisture data as a product that can be effectively used for diverse applications such as water management, agricultural production, drought prediction and flood forecasting.