Evaluating and Merging the Capability of Assimilating Satellite Hydrometeor Retrievals into GSI for HWRF Application

To increase the utility of satellite measurements of cloud and precipitation information in the Hurricane Weather Research and Forecasting (HWRF) model, the capability to assimilate satellite hydrometeor retrievals is added to the Gridpoint Statistical Interpolation (GSI) within the HWRF. That is, the retrievals from the Hurricane Goddard PROFiling (Hurricane GPROF) along with two observation operators are introduced to HWRF-GSI. The first observation operator (OO1) is developed with the purpose to adjust the environment in order to support the existence of cloud condensate without directly introducing cloud hydrometers. The formulation of such observation operator is then a vertical integral of super-saturated water vapor with respect to liquid or ice. In contrast, the second observation operator (OO2) uses the Ferrier-Aligo microphysics scheme and directly adjusts the existing cloud condensate. The two above-mentioned observation operators along with their tangent linear and adjoint parts are implemented and merged to the GSI trunk. Two HWRF-GSI experiments are carried out using three Atlantic hurricanes during 2014. Both experiments assimilate the Hurricane GPROF hydrometeor retrievals into the innermost domain of HWRF where one uses OO1 and the other uses OO2. Results from the two experiments will be presented.