Extended Abstract (12K)12C.3
Influence of ENSO on the Indian Ocean dipole
Toshiaki Shinoda, NOAA/CDC, Boulder, CO; and M. A. Alexander and H. H. Hendon
Coupled model experiments are used to investigate Indian Ocean SST variability associated with ENSO via an "atmospheric bridge". An ensemble of 16 atmospheric general circulation model (AGCM) simulations are performed in which observed SSTs are specified in the central and eastern tropical Pacific Ocean over the period 1950-1999. The remainder of the global oceans are simulated using a grid of 1-dimensional mixed layer models
Composites of SST and surface fluxes for warm and cold ENSO events for the period 1950-1999 are formed. The coupled model simulates some aspects of the observed Indian Ocean SST anomalies associated with ENSO including the basin-wide warming and development of a zonal dipole structure in Northern autumn. Surface flux anomalies associated with ENSO in the eastern tropical Indian Ocean agree with NCEP reanalysis fluxes reasonably well. AGCM and coupled model experiments suggest that a large portion of surface flux amomalies in the eastern tropical Indian Ocean associated with ENSO is remotely forced by the SST variation in the eastern tropical Pacific. The remotely forced SST in the eastern tropical Indian Ocean significantly contributes to the dipole variation.
Session 12C, Ocean-Atmosphere Interaction I (Parallel with Sessions 12A, 12B, and 12D)
Thursday, 2 May 2002, 9:00 AM-10:30 AM
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