GISS Lunch Seminar
Speaker: Chris Collimore (CUNY)
Title: Evidence that abundant aerosols help cloud clusters develop into tropical cyclone

Abstract:
The relationship between aerosol concentrations and tropical cyclone (TC) formation is investigated. 220 convective cloud clusters in the tropical Atlantic that developed into TCs (developers) and 214 tropical Atlantic clusters that dissipated before becoming a TC (nondevelopers) were examined. Two subsets were created, containing only clusters with similar environments in regard to variables known to be important for TC genesis: sea surface temperatures, mid-level humidity, vertical wind shear, lapse rates, and low-level vorticity. With these two subsets taking other relevant factors "out of the picture", aerosol content (as measured by satellite-derived aerosol optical depth) near developers was averaged; likewise for nondevelopers. The average aerosol content surrounding developers was significantly higher than that surrounding nondevelopers. Aerosol content was particularly high in a region to the northwest of the developers. Logistic regression analysis, using the full datasets, also indicates a positive correlation between aerosols and TC formation. The strong, positive correlation between aerosol content and TC genesis suggests high aerosol concentrations promote TC development. Possible mechanisms linking aerosols to TC formation are discussed.