Soil moisture bimodality over Land–Atmosphere hotspot regions at intraseasonal and interannual timescale.

This study examined boreal summer soil moisture using long-term satellite observations to study the bimodal probability distribution function (bimodality) of the surface soil moisture for the land-atmosphere coupling hotspot region, i.e., United States, Sahel and India. Although boreal summer soil moisture bimodality has been detected globally, it has not yet been established how surface soil moisture bimodality is caused. In this comparative multiregional study of surface soil moisture, the object was to classify India, Sahel, and Unites States regions into inter-annual or intra-seasonal soil moisture variation-based soil moisture bimodality. It was found that soil moisture bimodality detection is sensitive to the number of observations and the selected time period window. For northern India, intra-seasonal soil moisture variation dominates for soil moisture bimodality, while in the case of the United States, intra-annual soil moisture variation is dominant.