HR: 13:40h
AN: OS33C-01    [Abstracts]
TI: An investigation of the Indian Ocean thermocline cooling during recent decades using an ocean general circulation model
AU: * Han, W
EM: whan@enso.colorado.edu
AF: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, Co 80309, United States
AU: Trenary, L L
EM: laurie.trenary@colorado.edu
AF: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, Co 80309, United States
AB: An ocean general circulation model, the HYbrid Coordinate Ocean Model (HYCOM), is used to understand the causes for the observed cooling trend of the Indian Ocean thermocline in the past few decades. The model basin covers the Indian and Pacific Oceans of 40oS-55oN, and is forced by 3-day mean ERA40 reanalysis products for the period of 1958-2000. HYCOM reasonably reproduced the thermocline cooling, which agrees well with the cooling trends shown in the Levitus data and SODA-POP data. Results from HYCOM suggest that the observed strongest cooling in the upper thermocline within 15oS-2oS is associated with enhanced upwelling caused by the enhanced upward Ekman pumping velocity ( ). This increased upwelling is consistent with the significantly strengthened Southern Subtropical Cell (STC), when the Cross-Equatorial Cell weakens. Remote influence from the Pacific shallow thermocline through wave transmission via the Indonesian Throughflow does not seem to have a significant contribution in this area, because the maximum shoaling of the thermocline occurs in the central-western basin and is weak near the ITF region. At deeper layers (below ~250m) and south of 15oS, however, remote forcing from the Pacific appears to be more important.
DE: 4500 OCEANOGRAPHY: PHYSICAL
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
DE: 4532 General circulation (1218, 1222)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting