COLA Report 16
An Examination of the AGCM Simulated Surface Wind Stress and Low
Level Winds Over the Tropical Pacific Ocean
Bohua Huang and J. Shukla
August 1995
Abstract
The monthly mean surface wind stress and winds in the lower troposphere for 1986-1992
simulated by the COLA atmospheric general circulation model (AGCM) forced with observed
sea surface temperature is compared with observations. It is found that the AGCM surface stress
has weak equatorial easterlies during boreal spring and weak ENSO signals over the central and
eastern Pacific Ocean. On the other hand, the AGCM winds at 850 mb are found to be in much
better agreement with the observations.
An empirical scheme is developed to reconstruct the AGCM surface wind stress, based
on the AGCM winds from 850 mb. The reconstructed wind stress is more consistent with
observations for both annual and interannual variability. A series of numerical experiments are
conducted using the observed, AGCM, and reconstructed surface stress to force an ocean general
circulation model. The results demonstrate that the low frequency ENSO signals are significantly
improved in the OGCM when the reconstructed data set replaces the original AGCM stress.
Improvements are evident in more realistic SST anomalies and variability of the thermocline
depth.
Complete copies of this report are available from:
Center for Ocean-Land-Atmosphere Studies
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last update: 31 August 1995
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