Synoptic conditions related to soil moisture-atmosphere interactions and unorganized convection in Oklahoma
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AbstractAtmospheric modification by anomalously dry or wet soils can both enhance and suppress convective activity. However, the localscale and mesoscale feedback governing soil moistureprecipitation coupling are embedded within the larger synopticscale environment. Despite their importance, synopticscale atmospheric conditions are rarely considered in studies examining soil moistureatmosphere interactions. We combine selforganizing maps of 500hPa geopotential height, spatial synoptic classification, and Hybrid SingleParticle Lagrangian Integrated Trajectory model air mass trajectories to determine if the synopticscale environment affects the ability of the land surface to force unorganized convection in Oklahoma. We identify several synoptic patterns that significantly impact the frequency of unorganized convection. Synoptic patterns characterized by midlevel troughs over the Southern Great Plains are less frequently associated with unorganized convective events. These patterns exhibit cool air advection in the midlevel and lower level of the atmosphere and are linked to suppression of convective activity. The synoptic patterns characterized by 500hPa ridging over the study region are more frequently associated with unorganized convective events. These patterns likely result in increased net radiation, vapor pressure deficit, and more homogenously dry soils. Unorganized convective events that occur during these synoptic conditions initiate preferentially over dry soils. We present evidence that the synopticscale environment can influence whether and how the land surface has an impact on convection.
