Abstract

The indices reflecting the warm or cold phases of the El Niño-Southern Oscillation (ENSO) phenomenon are commonly based on sea surface temperature (SST) anomalies in cleverly chosen sectors in the Tropical Pacific Ocean. These climate indices, used as predictors of remote climate oscillations, have been successful in most studies of the effects of ENSO forcings on drought anomalies or unexpected floods worldwide. However, there is one difficulty that bothers researchers: the diversity of these remote effects. One of the regions of the world that has attracted the attention of scholars of the remote effects of ENSO oscillations is Northeast Brazil. The main reason for this interest is the great vulnerability of this region to droughts due to the social and economic fragilities that have persisted there for more than two centuries. This study proposes the experimental use of essential atmospheric indices, such as convective instability, as indicators of the presence of cumulonimbus in the Tropical Pacific in response to El Niño episodes. It is well known that the remote effects of El Niño events occur due to cumulonimbus formation in the Tropical Pacific in response to the additional supply of heat and humidity in areas with warm surface waters. However, these tropical cumulus clusters respond not only to surface heating but also to other forces associated with atmospheric circulation. This study has shown that such cumulonimbi can form in areas that are slightly apart from the sectors with the greatest surface heating.

This work is licensed under a Creative Commons Attribution 4.0 License.