Detecting soil moisture impacts on convective initiation in Europe

Abstract

Feedbacks between soil moisture and precipitation are important for understanding hydroclimatic variability in many regions. However, much uncertainty remains about how land surface fluxes influence the initiation of deep convection locally. While some studies consider only atmospheric and soil profiles, in a one-dimensional sense, others have argued that horizontal variability in fluxes plays an important role in convective triggering, via mesoscale circulations. This paper presents the first comprehensive observational analysis over Europe linking convective initiation to soil moisture, based on satellite observations of cloud top and land surface temperature, and soil moisture. The results show that convective initiations are favored on the downwind side of dry surfaces, close to wetter areas. The signal is clearest following dry periods and under light winds, consistent with forcing by a mesoscale circulation. Overall, the detected signal in Europe is weaker than in previous Sahelian analysis, but key spatial characteristics are essentially the same.