Temporal evolution of summer convective activity over the Americas warm pools

Abstract

The present analysis describes the temporal evolution of various meteorological parameters over the Americas warm pools that are related to the occurrence of the Mid Summer Drought (MSD). Contrary to what has been suggested by some authors, the bimodal structure of precipitation over the Pacific side of Mesoamerica is not a form of intraseasonal variability in convective activity related to the Madden Julian Oscillation, but a characteristic of the annual cycle in precipitation. The MSD – sea surface temperature (SST) ‐ radiation relationship proposed by Magaña et al. [1999] partially hold during the summer of 2001, when the Climate Experiment over the Americas Warm Pools (ECAC) field campaigns were conducted, with the SST exhibiting a bimodal structure in the MSD region. The maximum in tropical convection over the Central America‐Caribbean coast appears to play an important role in modulating convective activity in the surrounding regions, through induced subsidence related to direct circulations. The Caribbean Low Level Jet (CLLJ) is in phase with maximum western Caribbean Sea convective activity, reaching maxima intensities in July.