HR: 10:45h
AN: A42B-02    [Abstracts]
TI: Observed Influence of Amazon rainfall on the Atlantic ITCZ and Atlantic Nino
AU: * Fu, R
EM: fu@eas.gatech.edu
AF: Georgia Institute of Technology, 311 Ferst Dr., Atlanta, Ga 300332, United States
AU: Wang, H
EM: Hui.Wang@noaa.gov
AF: RSIS & NOAA/NWS/NCEP/Climate Prediction Center, 5200 Auth Road, Camp Springs, MD 20746-4304, United States
AB: Most of previous studies on climate variabilities of the tropical Atlantic Ocean have been focused on remote and internal oceanic processes or atmosphere-ocean interaction. In comparison, relatively few studies have examined the influences from adjacent continents, especially the influence of rainfall over the South American continent. Using the Tropical Rainfall Measuring Mission (TRMM) daily rain-rate dada, the QuikSCAT ocean surface wind and PIRATA buoy data, we have found that convection developed over the Amazonia appears to propagate eastward across the Atlantic and then into Africa. Such changes modulate the intensity and location of the convection within the Atlantic ITCZ and result in a zonal oscillation of the ITCZ between the west and east equatorial Atlantic Ocean. The eastward propagating disturbances appear to be an atmospheric Kelvin wave with a period of 6 to 7 days and a phase speed of around 12 m s-1. Such convectively coupled Kelvin wave is particularly strong during boreal spring and dominates the synoptic variations of the lower and upper troposphere winds. Our results further suggest that the interannual changes of these convective coupled Kelvin waves have an important influence on trigging the onset of Atlantic Ninos. In particular, anomalously late northward withdraw of the South American rainfall in boreal spring lead to stronger Kelvin wave activities and stronger westerly wind anomalies in the western equatorial Atlantic. The latter triggers a change of the slope of the thermocline in the equatorial Atlantic Ocean and induces sea surface temperature anomalies in the eastern Atlantic. These changes contribute to the onset of the Atlantic Nino in earlier boreal summer.
DE: 0429 Climate dynamics (1620)
DE: 0758 Remote sensing
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1855 Remote sensing (1640)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly