Numerical experiments to the Subtropical Cyclone "Anita" using WRF model

The Wheater Research and Forecasting Model (WRF) were used to simulate the subtropical cyclone Anita, which occurred between March 4 and 12 of 2010. These cyclone instigated weather forecast centers around the world, since models indicated that it would atypically move to southwest. Numerical models indicated the formation of Anita, but the intensity and location showed to be very sensitive to the anticipation of the forecast. Therefore, numerical experiments with WRF were conducted in order to evaluate the sensitivity of Anita cyclone by changing different configurations/parameterization: (a) relaxation zone ofthe model; (b) ocean mixed-layer model; (c) Betts-Miller-Janjic cumulus parameterization; (d) anticipation (24,48, 72h). Simulations used a 25 km resolution grid, and boundary and initial conditions from FNL/NCEP. Results were compared with the National Centers for Environrnental Prediction (NCEP) analyses and the Tropical Measuring Mission (TRMM) in terms of precipitation. Modifying between 5 and 40 columns/rows the relaxation zone conditions didn't seemed to present a large impact in simulating the intensity and position of the cyclone, deepening the low pressure system in general, reaching 12 hPa of difference. Studies with 72h of anticipation tended to move the cyclone towards the continent, while 24h simulations presented better agreement with the cyclone path. Ocean mixed-layer model also didn't indicate an apparent effect with respect to the variables mentioned above. However Betts-Miller-Janjic cumulus parameterization ensured similar results to the observed, mainly for 72h simulations. Due to deepen low pressure systems, the precipitation was, in general, overestimated in the experiments once compared to the TRMM analyses. Betts-Miller-Janjic cumulus parameterization showed a higher correlation between 72h experiments and the observed, accurately reproducing the position of the precipitation cores associated with the subtropical cyclone Anita