EL ENOS, el IOS y la corriente en chorro de bajo nivel en el oeste del Caribe

Abstract

Using Southern Oscillation Index (SOI) data from 1900-1997 and some other shorter SOI series before 1900, it is determined through filtering and basic statistics, the duration of the warm/cold phases of the events associated to El Niño Southern Oscillation (ENSO) during these periods. A comparison of these results is made with those of other authors for some particular periods. A reasonable agreement is obtained of the beginning, end and duration of the ENSO events. The above results are utilized to study the behavior and possible dynamical response of the Low Level Jet (LLJ) over the western Caribbean, during the boreal summer when this jet develops under an El Niño, La Niña or normal conditions. In spite of the fact that the analysis includes relatively few events for each observed phase of the ENSO signal, it can be said that the region where the LLJ is located experiences under warm ENSO conditions an increment of the zonal flow. This increment has been associated with a possible enhancement of the precipitation in the western region of the Caribbean and more stable conditions in the Pacific side of Central America during the Northern Hemisphere summer months. On the contrary, decrease in the intensity of the trade winds associated with the LLJ during the cold phase of ENSO is observed; which can possibly be related to a less intense orographic rainfall conditions in the western part of the Caribbean during these months.