Avaliação de mudanças na freqüência de sistemas frontais sobre o Sul da America do sul em projeções do clima futuro

• Autores: Martins Andrade, Kelen; Muller, Gabriela Viviana; Cavalcanti, Iracema F .A.; Fernández Long, María Elena; Bidegain, Mario; Berri, Guillermo Jorge
• Año de publicación: 2012
• Idioma: portugués
• Tipo de recurso: artículo
• Materia: Sistemas frontais; clima futuro; América do Sul
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

The frequency of frontal systems reaching the south of South America is compared with reanalysis, NCEP/NCAR, and results of GFDL and Hadley models for the future climate A2 scenario. For the present climate the analyzed period was 1961-1990 and for future projections, 2081-2100, from May to September. Three regions were analyzed to identify the frontal systems, in areas of Brazil, Uruguay, Paraguay and Argentina. The following criteria were used: increase of sea surface pressure, reduction of the temperature and change of the meridional wind at 850hPa, in two consecutive days. Selected cases with temperature drop above 5 degrees, considered the most intense, were also analyzed. For the present climate it was observed that the models simulated well the synoptic characteristics of frontal systems. However, when comparing the frequency of frontal occurrence between reanalysis data and models simulations, the GFDL and Hadley models overestimated their numbers. The Hadley model overestimates further more than the NCEP and GFDL in present climate. The positive trend observed in area 3 from NCEP reanalysis is not simulated by the models. When the most intense systems are selected, the GFDL model shows higher overestimation in number of frontal systems. Both models indicate an increase of frontal systems frequency in the future in the three areas, although less in area 3.
The frequency of frontal systems reaching the south of South America is compared with reanalysis NCEP/NCAR and results of GFDL and Hadley models for the future climate. Three regions were analyzed to identify the frontal systems, in areas of Brazil, Uruguay, Paraguay and Argentina. The following criteria were used: increase of sea surface pressure, reduction of the temperature and change of the meridional wind at 850hPa, in two consecutive days. Selected cases with temperature drop above five degrees, considered the most intense, were also analyzed. For the present climate it was observed that the models simulated well the synoptic characteristics of frontal systems. However, when comparing the frequency of frontal occurrence between reanalysis data and models simulations, the GFDL and Hadley models overestimated their numbers. The Hadley model overestimates further more than the NCEP and GFDL in present climate. The positive trend observed in area 3 (65ºW-60ºW, 33ºS-38ºS) from NCEP reanalysis is not simulated by the models. When the most intense systems are selected, the GFDL model shows higher overestimation in number of frontal systems. Both models indicate an increase of frontal systems frequency in future in the three areas, although less in area 3.
Fil: Martins Andrade, Kelen. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; Brasil
Fil: Muller, Gabriela Viviana. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina
Fil: Cavalcanti, Iracema F .A.. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; Brasil
Fil: Fernández Long, María Elena. Universidad de Buenos Aires. Facultad de Agronomía; Argentina
Fil: Bidegain, Mario. Universidad de la República; Uruguay
Fil: Berri, Guillermo Jorge. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina