Tuesday, 24 January 2012
Impact of Cycled 3DVAR Assimilation of COSMIC Observations on Simulated Dynamical and Thermodynamical Structures in Nor'easters
Hall E (New Orleans Convention Center )
Since their 2006 launch, satellites from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission have provided bending angle and refractivity profiles of occulted Global Positioning System signals with penetration into the boundary layer. These profiles benefit weather forecasts once assimilated and transformed into estimates of water vapor content and temperature. Assimilation of these data into non-hydrostatic, prognostic weather models has been shown to demonstrate a positive impact upon GFS, ECMWF, and WRF model simulations. Previous studies have attributed these positive results due to its global coverage, all-weather capability, high accuracy, high precision (twice as precise as radiosondes), and high-vertical resolution (~60 m). In this study, the impact on WRF-ARW version 3.2 simulations of nor'easters to three-hourly-cycled, three-dimensional variational data assimilation of COSMIC radio occultation data is assessed. Previous work demonstrated simulation improvement in terms of reduced energy norm and RMSE values that was commensurate with similar studies. The present study focuses on the contribution moisture alone has on the overall simulation and a comparison between COSMIC data assimilation and radiosonde data assimilation during the same period. We expand upon previous results by determining how COSMIC data assimilation affects dynamics, microphysics, and precipitation fields. Preliminary results show improvements in the timing, placement, and intensity of 500-hPa geopotential height fields attributed to COSMIC data assimilation.