versión On-line ISSN 1850-468X
The subtropical jet stream over South America is identified from monthly mean wind fields obtained from NCEP/NCAR reanalysis during the period 1978-1999. Zonal wind vertical cross-sections are used to determine its intensity and latitudinal position. Then, 200-hPa wind intensity fields are used to identify the subtropical jet stream core. The results obtained in this study and the comparison with those obtained by other authors show the efficiency of the reanalysis in detecting the monthly mean subtropical jet stream (STJ). The intensity and latitudinal position of the STJ are related in such a way that the STJ weakens as it moves poleward. However, this behavior is not observed in October, which defines a particular feature of the STJ in South America. The analysis of the subtropical jet stream core position shows a preferred location over eastern Argentina and Uruguay. Also, a secondary preferred location is found during winter over the tropical Pacific Ocean off the South America coast. Whereas the cores prefer to remain over the continent instead of the ocean during summer, they are considerably more zonally widespread in winter.
Palabras llave : Subtropical Jet Stream; South America; Regional Climate.