Uso de modelos numéricos regionais para simular a brisa marítima na Antártica

Abstract

In the present study, three different problems associated with the numerical simulation of small-scale meteorological processes are investigated. In the first problem regards the frequency, location and characteristics of rainfall induced by the convergence of different sea breezes systems in Salento peninsula (south of Italy). Such events were studied, considering the satellite images/radar and output fields from two models (MOLOCH and WRF) in the summer of 2011-2013. In total were selected 20 days, when rainfall due to the sea breeze convergence was clearly shown in satellite images and radar. The two modeling systems analyzed here, are able to reproduce the convergence inland: in the 20 cases that have been detected, only two cases for each model do not show any convergence pattern due to sea breeze convergence. The results show that the limited area models with a few km spacing grid, are suitable tools for simulating these phenomena, in relatively small scale. In the second problem under different PBL and mycrophysics schemes in WRF model are compared with data collected by a micrometeorological tower on Deception Island, for distinct meteorological conditions. For air temperature, the different experiments produced a daily cycle with smaller amplitude than in observations. The variability among schemes was less than 1oC, mostly because of SST influence and their different capabilities of solving cloudiness. For the clear sky day, the short wave radiation forecast is largely dependent on the mycrophysics scheme used and not as much on the PBL ones, but for long wave radiation the schemes produced similar results. But when there is a extra-tropical cyclone acting, THOMPSON mycrophysics scheme performs better than WSM3. For the zonal wind, the variability among PBL schemes is generally larger (1-3 m/s) than among the mycrophysics ones (less than 1 m/s). WSM3 scheme is generally better suited for forecasts in extra-tropical cyclone days. For the meridional wind component, there is little difference among mycrophysics and PBL schemes. In the third problem under meteorological patterns of the convergence zone induced by different sea breeze systems on Antarctic peninsula are analyzed for the summer period of 2013-2015. Such events are selected by satellite images (59 days), which are simulated WRF; a total of 21 days have been detected convergence due to the sea-breeze. The model variables are analyzed before the occurrence of sea-breeze, in order to provide a snapshot of the environment development. The synoptic conditions are identified, considering the average values and anomaly. The average convergence is positive between 14 and 23 UTC, period that sea-breeze occur, with maximum convergence at 18 UTC (1.5 x10-4 s). There is a strong potential temperature gradient during mature sea breeze and high differences sensible heat flux between at the top of the mountains and low areas.