Avaliação das Mudanças na Frequência de Sistemas Frontais Para o Sul da America do Sul no Clima Futuro

ANDRADE KELEN; MÜLLER, GABRIELA V.; CAVALCANTI IRACEMA F.A; FERNANDEZ LONG MARIA ELENA; BIDEGAIN MARIO; BERRI, GUILLERMO J.

Buenos Aires

Congreso; X Congreso Argentino de Meteorología y XIII Congreso Latinoamericano e Ibérico de Meteorología; 2009

The frequency of frontal systems reaching the south of South America is compared with reanalysis, NCEP/NCAR, and results of the A2 scenario for future climate models GFDL e Hadley. For the present climate the analyzed period was 1961-1990 and for future it was the scene 2081-2100 from May to September. The analyses to identify the cases of frontal systems had been made in 3 regions: area 1 (52W-57W, 23S-28S); area 2 (52W-57W, 28S- 33S) and area 3 (65W-60W, 33S-6S). For the identification of the frontal system was used the following criteria: increase of sea surface pressure, reduction of the temperature and change of the meridional wind at 850hPa, in two consecutive days. In this study was also selected cases with drop of temperature above 5 degrees and they were considered the most intense. For the present climate it was observed that the analyzed models had simulated well the synoptic characteristics of frontal systems. However, when compared the frequency of occurrence of the fronts between reanalysis data and models simulations, we observed that the GFDL and Hadley models overestimated their numbers. The Hadley model overestimates further more than the NCEP and GFDL ones, both present climate and future. However, when it is selected the most intense systems, the GFDL model is the one that most overestimates the number of frontal systems.