Preliminary Results Using a Coupled Ocean-Atmosphere Vortex Specification Algorithm for the WRF-ARW Using NHC/TPC Observations and Vertical Structures Derived from Analytical and Observational Models

A tropical cyclone (TC) vortex specification algorithm, using observations provided by the National Hurricane Center (NHC)/Tropical Prediction Center (TPC), has been developed for the Weather Research and Forecasting (WRF) Advanced Research WRF (ARW). This hybrid method employs variations to previously established methods which isolate and remove a first-guess analyzed vortex (Kurihara et al., 1993, 1995), specify a sea-level pressure profile for a synthetic vortex according to NHC/TPC observations (Mathur, 1991; Holland, 1980), and a balanced near-surface wind profile (Holland, 1980) for the respective TC. Vertical kinematic and thermodynamic profiles are derived from drop- and radiosonde profiles as well as Global Position System (GPS) Radio Occultation (RO) observations obtained within TC environments (Winterbottom et al., 2007), respectively. The observations are ingested into the WRF-ARW 3-Dimensional VARiational data assimilation (3DVAR) system (Barker et al., 2001) to specify a more realistic TC vortex for the WRF-ARW forecast initialization. The 3DVAR specified vortex, is shown to be more consistent with the NHC/TPC observations for the intensity of the respective TC. Initial forecast results indicate that the specified vortex better correlates with vortex position and intensity at verification. Preliminary results using a 1-dimensional mixed-layer ocean model (Kantha and Clayson, 1994) coupled to WRF-ARW will also be presented.