Examining the Impacts of Assimilating Vertically Integrated Ice in WRF Simulations of Two Nocturnal Mesoscale Convective Systems

Abstract To better understand nocturnal mesoscale convective system (MCS) dynamics, a novel data assimilation (DA) method has been developed and applied to the Weather Research and Forecasting (WRF) mesoscale model for two Plains Elevated Convection at Night (PECAN) MCS cases. This method is similar to the lightning DA (LDA) technique discussed in Fierro et al. (2012), https://doi.org/10.1175/mwr‐d‐11‐00299.1 , wherein lightning data is used to nudge a column toward saturation by increasing water vapor mixing ratio. For the present study, vertically integrated ice (VII) is used in lieu of lightning to introduce virtual thermal buoyancy in the updraft column. Since VII is indicative of deep convective updrafts, VII DA should introduce buoyant updrafts before the appearance of lightning while also decreasing errors in timing and location of convection initiation. This study demonstrates the skill of the VII method compared to both a control simulation and a LDA simulation.