Influência dos fenômenos acoplados oceano atmosfera sobre os vórtices ciclônicos de altos níveis observados no Nordeste do Brasil.

Abstract

We analyzed the behavior of 311 Upper-Tropospheric Cyclonic Vortex (UTCV) observed from january 1980 to december 2009, the region Northeast Brazil (NEB) and adjacent South Atlantic. Was used data from Anomalies of Sea Surface Temperature (SST) and Atlantic Oceans Pacific, the zonal (u) and meridional wind (v), precipitation and Index of the Pacific Decadal Oscillation (IODP). From the components of wind was calculated fields of relative vorticity, horizontal divergence and the rotational and divergent components of the wind. The methodology consisted of graphics and Principal Component Analysis (PCA), which allowed the verification of the influence of SSTA in the occurrences of vortex. The results showed that during all stages of VCAN was noticeable in 90% of cases the presence of the Bolivian high (BH) and the anticyclonic vorticity from this center served a decisive maintenance of the vortex. The preferred area for training was VCAN over the tropical Atlantic and under normal conditions of the waters of Pacific (45.7% of events). In El Niño events, it was noticed that the maximum VCAN occurred in regions where the SST Niño 1 +2 and Niño 3.4 were more heated than the other regions of the Niños. Also concerning the SSTA Pacific observed that when the IODP was positive and the El Niño was set were recorded more VCAN than when the IODP was negative and had setting of La Niña. Observing the rotational components and divergent wind, it was seen how these two antagonistic components. The total pluviometric over NEB observed during the events followed showed a great variability due to VCAN positioning. The PCA were found two Principal Components (PC) that explained more than 50% of the variability in the number of occurrences of VCAN according to the SSTA in the Atlantic and Pacific. So it follows that the coupled ocean-atmosphere phenomena act in a decisive VCAN dynamics of operating in northeast Brazil.