Spatial Variability of Soil Moisture after Rainfall Events and Its Role in Triggering Convection in Semi-arid Regions

Abstract:

Soil moisture-atmosphere interactions play a crucial role in the development of convection. Previous studies based on observations indicated that strong soil moisture gradients have higher probability of convective initiation than homogeneous soil moisture conditions, and that precipitation preferentially occurs over drier soils. In this study, remote-sensing datasets are used to investigate how soil moisture spatial distribution will be modified after afternoon precipitation events, and whether the subsequent soil moisture distribution in the next day's morning is advantageous to trigger convection. Preliminary results show that when soil conditions are dry, afternoon precipitation events tend to maintain or increase the soil moisture heterogeneity. This implies that the new soil moisture spatial distribution after the precipitation event might favor convective triggering, thus enhance precipitation persistence in semi-arid regions. We will further explore whether numerical models can capture such soil moisture variations and persistence.