Climatologia de bloqueios sobre o Oceano Pacífico Sul: período de 1960 a 2000
Damião M.C.M.., Trigo R.M., Cavalcanti I.F.A. and DaCamara C.C.
Revista Brasileira de Meteorologia,20(2), 175-190.
BLOCKING EPISODES OVER THE SOUTHERN PACIFIC OCEAN FOR THE 1960-2000 PERIOD: CLIMATE IMPACTS AND ASSOCIATED PHYSICAL MECHANISMS
Blocking episodes in the Southern Hemisphere are characterized by persistent anticyclones, centred on the 60°S latitudinal belt, and they are important because they induce large meridional displacements of synoptic scale transient eddies. Here, we present a comprehensive multivariable characterization of the climate impacts of blocking over Southern Hemisphere, in particular, for the Southwestern and Southeastern Pacific sectors, using a 41-year (1960-2000) consistent dataset extracted from the NCAR/NCEP reanalysis. Anomaly fields of the atmospheric variables are analyzed, such as anomalous wind flow, 500 hPa anomalous geopotential height, anomalous vorticity at 850 hPa, sea level pressure and cloud cover. The impact of the blocking events on South America continent climate is performed based on precipitation rate, maximum and minimum temperatures. There is a reduction in precipitation rate over Brazil, mainly in summer, and increase of maximum and minimum temperature over southern Brazil, Paraguay, Uruguay and northern Argentina in the winter, during blocking. Finally, we have computed the impact of El-Niño and La Niña years on seasonal frequency of blocking episodes. Both the number of blocked days and blocking events increase during El Niño episodes, compared with La Niña years.