The role of Easterly Waves on the Tropical Americas Climate

Easterly wave activity may lead to a wet or dry year in the Mesoamerica region. The interaction between easterly waves (EW) and the Caribbean low-level jet (CLLJ) is a key element in the generation or amplification of tropical waves over the Caribbean Sea. However, it is necessary to examine various aspects of the transient mean flow interaction over this region in order to explain various characteristics of the tropical Americas climate and its variability. It is found that the CLLJ easterly wave interaction may determine the characteristics of the intraseasonal, interanual, interdecadal climate variability and even long term trends of regional climate. An stronger (weaker) than normal CLL jet may lead to less (more) easterly waves reaching the Mexico Central American region.

The easterly wave CLLJ interaction takes place through a barotropic instability process. The perturbations anisotropy also appears to be an important element for the CLLJ to accelerate from to May to July and decelerate from August to October). The implication of this type of wave mean flow interaction for the Caribbean and Mesoamerican region is discussed.