HR: 17:05h
AN: GC44A-06    [Abstracts]
TI: Variability and Expansion of the Tropical Ocean Warm Pool
AU: * Hoyos, C D
EM: choyos@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332, United States
AU: Webster, P J
EM: pjw@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332, United States
AB: The tropical warm pool plays a determining role in the global climate since it acts as a sorce of thermodynamic forcing for the atmospheric general circulation. The warm pools (SST>28°C) extend from the Indian Ocean, across the Indonesian Archipelago into the western Pacific with a secondary area crossing Central America into the Caribbean and the central Atlantic ocean. The heating in the atmosphere above the warm pool influences climate over wide ranges of the planet. As there are zonal asymmetries in the extent of the warm pool, and hence variations in the locations of total heating of the atmospheric column, the warm pools also create centers of diabatic heating along the equator which set up the position and strength of the east-west Circulations which play integral roles in the coupled ocean-atmosphere tropical climate. In fact, almost all of the global vertically integrated heating resides over waters >27°C. The tropical warm pool is characterized by large-scale variations of SST on time scales that range from intraseasonal to interdecadal, considerably altering the forcing to the atmosphere. In addition to the existence of the large variability of the tropical warm pool SST, there is an upward trend in the tropical warm pool area, which is evident in the Atlantic, Indian and Pacific oceans with the area encompassed by the 28C isotherm groewing by 67% since 1920. Changes in the zonal and meridional circulation associated with the variability and expansion of the warm pool are studied using NCEP-NCAR and ERA40 reanalsysis. It is found that the impacts extend around the tropics and are associated with a slowing down of the Asian monsoon circulation and modulation of the of the equatorial Walker cells. Analysis of the IPCC-CMIP3 models for the 20th century show similar changes in the warm pool extent suggesting that changes that occur under different future emission scenarios may poossess credence. With greenhouse warming it is found that the warm pool doubles in size from the observed values in the 21st century. We explore the changes in the column integrated heating in the different CMIP3 integration scenarios to see if the threshold between columnar heating and cooling changes to higher temperatures and whether there will be linear or nonlinear transitions. Results suggest the existence of important changes in the zonal and meridional circulation in the Atlantic, Pacific and Indian Ocean in association with the expansion of the tropical warm pool. We also show an example of how the expansion of the tropical warm pool not only has effects on the atmospheric general circulations but also in the dynamics and sustainability of the marine biodiversity. Corals for example are highly sensitive to temperature increase and could face extensive bleaching under the expansion of the tropical warm pool.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1620 Climate dynamics (0429, 3309)
DE: 1626 Global climate models (3337, 4928)
DE: 1630 Impacts of global change (1225)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting