Monday, 12 January 2009
A Study of Ocean-Atmospheric Interactions and Associated Tropical Cyclone/Hurricane Activity over the Gulf of Mexico using Coupled Atmospheric Modeling System (CAMS)
Hall 5 (Phoenix Convention Center)
In the present study, we have developed NCAR Weather Research and Forecasting (WRF) model using MM5 output as initial and lateral boundary conditions to simulate the surface features and surface fluxes associated with land falling hurricane Opal that formed and developed over the Gulf of Mexico during September 27 - October 5, 1995. Coupled Atmospheric Modeling System (CAMS) is defined as MM5 model used in initializing the WRF model for forecast and diagnostic studies. NCEP Global Analyses containing surface, tropospheric, tropopause and lower stratospheric analyses are used to initialize MM5 run. Objective analysis in MM5 is done using NCEP ADP global upper air and surface observations, which are synoptically sorted. Observed data sets for comparison used including observations from FAA/NWS sites, satellite images and other applicable surface observing networks. This is an effort in data assimilation to produce varying results of the model output for direct comparison and future diagnostic studies tropical cyclone/hurricane structure and intensity change. The WRF model simulations for 36-hr period forecasting have been improved by ingesting MM5 output for initial and lateral boundary conditions. The results of the study have suggested the following: The maximum values simulated during land falling were 100 Watts/m2 (heat flux) and 2.4 in (accumulated convective precipitation) with a minimum central pressure of 924 mb. The average sea surface temperature of 28„aC was observed over the Gulf of Mexico. The fluxes, precipitation and wind were observed and simulated mostly south, northeast and eastern sectors of the storm. WRF predicted central pressure, wind speed, precipitation, intensity change and track associated with hurricane Opal close to the observations. Efforts are being made to improve the boundary layer physics and parameterization schemes.