Evaluation of the ASCAT surface soil moisture product for agricultural drought monitoring in USA

Soil moisture is a good indicator of agricultural drought. The Advanced Scatterometer Surface Soil Moisture (ASCAT SSM) product provides daily estimates of surface soil moisture and shows high potential for drought monitoring at global scale. However, its regional application still needs further investigation. In this paper, the effectiveness of ASCAT SSM product for drought monitoring in 3 major winter wheat producing states of the US (Oklahoma, Kansas and Nebraska) was evaluated using intensive in situ measurements from North America Soil Moisture Database (NASMD). The results indicate ASCAT SSM product is generally effective for characterizing drought conditions across different stations, with better representation of soil moisture at 5cm than 10cm depth. ASCAT SSM product shows varying capability for drought monitoring across the entire year, with a better capability observed around March-July and October-November. Also, better drought monitoring capability is found for the ASCAT descending SSM than for the ascending SSM.