HR: 08:15h
AN: H51G-02 INVITED     [Abstracts]
TI: Atmospheric dynamics hypotheses for midsummer droughts
AU: * Mapes, B
EM: mapes@miami.edu
AF: University of Miami - RSMAS, 4600 Rickenbacker Cswy, Miami, FL 33149, United States
AB: This talk will review mechanisms that I hypothesize are responsible for the Central American mid-summer drought. Proximate causes, positive feedbacks, and ultimate causes are carefully distinguished. The proximate cause of dry weather appears to be a change in the configuration of the North Atlantic subtropical high pressure cell. Feedbacks, for example from latent heating anomalies associated with the rainfall shift are apparently strong and positive. Logically, though, these anomalies cannot "explain" their own existence and timing. We suggest that the ultimate causes involve the zonal mean zonal flow. If so, the midsummer drought phenomenon spans all scales from truly global to convective, so predicting its variations from year to year may depend on a challenging array of faraway factors and physical process parameterizations.
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
SC: Hydrology [H]
MN: 2007 Joint Assembly