Study of Tropical Oceans In Coupled models (STOIC)

Contact: Mike Davey and Ken Sperber

(a companion project to ENSIP)


STOIC was initiated by CLIVAR-WGSIP in 1996, with the aimed of identifying common strengths and weaknesses of coupled models in tropical ocean regions. It is complementary to another WGSIP project (ENSIP) that concentrated on ENSO and the equatorial Pacific. Fields of tropical sea surface temperature, surface wind stress and upper ocean vertically-averaged temperature were collected from 24 models (22 CGCMs, of which 14 with no tropical flux adjustments) and compared with observed behavior with regard to annual mean, seasonal cycle, and interannual variability characteristics. Reports of results have been published.

Main results:

  • for annual mean equatorial SST: commonly the model central Pacific is too cool, and the zonal gradient has the wrong sign in the Atlantic.
  • for SST interannual variability: equatorial Pacific variability is commonly too weak;
  • few models correctly simulate the observed Pacific 'horseshoe' pattern of negative correlations with Niño3 SST anomalies; few models correctly simulate observed Indian-Pacific lag correlations.
  • for equatorial zonal windstress: annual mean windstress is often too weak in the central Pacific and in the Atlantic, but too strong in the west Pacific; windstress interannual variability is commonly much too weak in the central Pacific.
  • for ENSO-related windstress anomalies: the models generally represent local and remote features well.
  • for upper ocean vertically-averaged temperature: no models have an equatorial Pacific seasonal cycle like that observed.

References:

  • Davey, M., M. Huddleston, K.R. Sperber et al., 2000: STOIC: A study of coupled GCM climatology and variability in tropical ocean regions (A detailed report of results, available on ftp.)
  • Davey, M., M. Huddleston, K.R. Sperber et al., 2002: STOIC: a study of coupled model climatology and variability in tropical ocean regions. Clim. Dyn., 18, 403-420.
  • Davey, M., M. Huddleston and K. Sperber, 2000: The CLIVAR-WGSIP STOIC project. CLIVAR Exchanges, 17, 21-23.