Does Soil Moisture Affect Warm Season Precipitation Over the Southern Great Plains?

Abstract

Numerous observational and modeling studies have addressed the impact of soil moisture on subsequent precipitation (primarily its initiation), yet consensus remains elusive. Here we quantify the relationship between soil moisture and precipitation amplification over the U.S. Southern Great Plains. Warm season (June–September) days for the 2002–2011 period (with ~1220 total days) are partitioned into three dynamic regimes based on daily water vapor convergence, among which afternoon precipitation event days are identified based on simple criteria. We find that antecedent soil moisture conditions are negatively correlated with subsequent afternoon precipitation magnitude for low dynamic regimes, but this correlation becomes positive for high dynamic regimes. In contrast, this correlation is markedly reduced in magnitude and becomes insignificant when all regime days are considered. These results are also confirmed by analyzing the precipitation histogram and diurnal cycle. Furthermore, different pathways are provided for precipitation amplification for low and high dynamic regimes.