Impact of soil moisture anomalies on seasonal, summertime circulation over North America in a Regional Climate Model

The impact of initial soil moisture on seasonal? summertime atmospheric circulation over North America is investigated using the National Centers for Environmental Prediction Regional Spectral Model (NCEP RSM). Three-month-long simulations are conducted for the two summers, May-June-July (MJJ) 1988 (drought in the Great Plains) and MJJ 1993 (a flooding event). Overall, the climate responses due to soil moisture anomalies in the RSM is in line with the previous findings from global models and observational studies, with strong positive feedback between initial soil moisture anomalies and simulated seasonal precipitation. The impact of the initial soil moisture anomalies persists for the 3-month integration period, but effects are mostly confined to the near-surface climate with little impact on the dynamic circulation in the upper troposphere. Influence of soil moisture anomaly on the low-level structure and their interaction with precipitation mechanism are highlighted. The regional climate responses in the RSM were not significantly dependent on the size of the domain of integration.