Use of a Reflectivity Operator Based on Double-Moment Thompson Microphysics for Direct Assimilation of Radar Reflectivity in GSI-Based Hybrid En3DVar

Abstract The assimilation of reflectivity ( Z ) within 3DVar or hybrid ensemble-3DVar (En3DVar) requires the adjoint observation operator. With En3DVar method, previous studies often use operators consistent with a single-moment microphysics scheme even when forecast model uses double-moment scheme. As such, only mixing ratios hydrometeors are directly updated by data (DA) system, leading to inconsistency between analyzed state variables and in prediction model. In this study, we formulated operator Thompson used numerical integrations; snow graupel components simplified using functions fitted T-matrix simulation results. This its implemented GSI DA system enable direct impacts new on convective storm analysis through cycles, ensuing 3-h forecasts first examined detail for tornado outbreak case 16 May 2017 Texas Oklahoma, then five additional thunderstorm cases. Forecast reflectivity, hourly precipitation, updraft helicity tracks subjectively evaluated, while neighborhood ETSs performance diagrams and/or precipitation. Compared experiments scheme, produces better smaller biases, improvement is somewhat larger higher threshold.