VARIABILITY OF THE INTENSITY AND LATITUDINAL POSITION OF THE SUBTROPICAL JET STREAM OVER SOUTH AMERICA AND ITS RELATIONSHIP WITH THE SEA SURFACE TEMPERATURES OF THE EQUATORIAL PACIFIC OCEAN

PABLO L. ANTICO; GUILLERMO J. BERRI

Denver, EUA

Conferencia; Eighth Conference on Climate Variations; 1999

American Meteorological Society

The relationship between climate variability in South America and the behavior of the subtropical jet stream has been investigated by a number of authors.  Kousky and Ropelewski (1989) observed, during warm ENSO events, an anomalous cyclonic circulation in upper-levels over southeast South America. This may contribute to the strengthening and eastward propagation of the subtropical jet towards the western South Atlantic.  Diaz et al. (1998) suggest that the subtropical jet would be connected with MCCs development and movement over the upper Rio de la Plata basin.   Also known, is the existence of a relationship between ENSO and zonal wind in the 200-hPa level in the Southern Hemisphere (Karoly 1989).  In North America, Mo et al. (1997) found an association between upper-level and low-level jets.  Hordij and Bordón (1987) (hereafter referred to as HB) studied the behavior of the subtropical and polar jets over South America.  Their work was based on daily analysis of upper-level maps and satellite imagery for the period October 1983-December 1985.  In the present work, we use monthly means of 200-hPa level zonal wind.  This data was obtained from NCEP model reanalysis from January 1978 to December 1998.  In order to determine the position and intensity of the subtropical jet over South America, latitudinal cross-sections was analyzed.  The annual timeseries for the intensity, the meridional position and the isobaric level of the jet were prepared.  Finally, the relationship between the subtropical jet and the sea surface temperatures (SST) on the equatorial Pacific Ocean is explored.