Recorded presentation3.6
Inter-Hemispheric Influence of the Atlantic Warm Pool on the Southeast Pacific
Chunzai Wang, NOAA/AOML, Miami, FL; and S. K. Lee, C. R. Mechoso, and D. B. Enfield
The Atlantic Warm Pool (AWP) with a large body of warm water is comprised of the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic. AWP variability occurs on seasonal, interannual, and multidecadal timescales. The AWP reaches its maximum size in the late summer and early fall, with large AWPs being almost three times larger than small ones. The warm pool alternates with northern South America as the seasonal heating source for the Walker and Hadley circulations in the Western Hemisphere. During the boreal summer, a strong Hadley circulation emanates from the AWP and forks into the subsidence region of the subtropical southeast Pacific. Observations show that the anomalous warm pool index is positively correlated with rainfall anomalies over the southeast Pacific where the drizzle (light precipitation) under the stratus cloud deck usually appears. ENSO and local SST anomalies in the southeast Pacific have little or nothing to do with the positive rainfall correlation. The link between the warm pool and the southeast Pacific is observed to be through the regional Hadley circulation. Anomalously large (small) warm pools strengthen (weaken) the summer Hadley circulation that emanates from the region of the warm pool into the southeast Pacific. This will change the subsidence over the southeast Pacific and thus the stratus cloud and drizzle. The NCAR community atmospheric model is further used to demonstrate the remote and inter-hemispheric response of the AWP to the southeast Pacific; that is, the AWP contributes to sinking over the southeast Pacific and hence the stratus cloud in the region.
Session 3, Variability of the American Monsoon (VAMOS) Ocean-Cloud-Atmosphere-Land Study (VOCALS): Part 3. Mesoscale Meteorology and Oceanography
Monday, 12 January 2009, 4:00 PM-5:30 PM, Room 128AB
Previous paper