Electrically-active hot towers in African easterly waves prior to tropical cyclogenesis.

摘要

It has been hypothesized that intense convective-scale "hot" towers play a role in tropical cyclogenesis via dynamic and thermodynamic feedbacks on the larger-scale circulation. In this study we investigate the role that widespread and/or intense lightning- producing convection (i.e., electrically-hot towers) present in African easterly waves (AEWs) may play in tropical cyclogenesis over the East Atlantic Ocean.;The 700 hPa meridional wind from the NCEP Reanalysis dataset was analyzed to divide the waves into northerly, southerly, trough, and ridge phases. Then composites were created of developing waves (i.e., waves that developed into tropical storms) and non-developing waves using various NCEP variables, lightning data, and brightness temperature data.;Results indicate that in all regions examined, the developing waves seem to be associated with more widespread and/or intense lightning-producing convection. The observations of synoptic-scale conditions more conducive to tropical cyclogenesis found in association with developing waves might be related to this enhanced convection.