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Some sensitivities of a coupled ocean-atmosphere GCM

Technical Report:

Abstract

A coupled ocean-atmosphere GCM is being developed for use in seasonal forecasting. As part of the development work, a number of experiments have been made to explore some of the sensitivities of the coupled model system. The overall heat balance of the tropics is found to be very sensitive to convective cloud cover. Adjusting the cloud parameterization to produce stable behaviour of the coupled model also leads to better agreement between model radiative fluxes and satellite data. A further sensitivity is seen to changes in low-level marine stratus, which is under-represented in the initial model experiments. An increase in this cloud in the coupled model produces a small improvement in both the global mean state and the phase of the east Pacific annual cycle. The computational expense of investigating such small changes is emphasized. An indication of model sensitivity to surface albedo is also presented. The sensitivity of the coupled GCM to initial conditions is investigated. The model is very sensitive, with tiny perturbations able to determine El Nino or non-El Nino conditions just six months later. This large sensitivity may be related to the relatively weak amplitude of the model ENSO cycle. (orig.)
Authors:
Stockdale, T; [1]  Latif, M; [2]  Burgers, G; [3]  Wolff, J O [4] 
  1. European Centre for Medium Range Weather Forecasts (ECMWF), Reading (United Kingdom)
  2. Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)
  3. Koninklijk Nederlands Meteorologisch Inst., De Bilt (Netherlands)
  4. Tasmania Univ., Hobart, TAS (Australia). Antarctic CRC
Publication Date:
Feb 01, 1994
Product Type:
Technical Report
Report Number:
INIS-mf-15074
Reference Number:
SCA: 540110; PA: DEN-94:0FN556; EDB-95:016911; SN: 95001306260
Resource Relation:
Other Information: PBD: Feb 1994
Subject:
54 ENVIRONMENTAL SCIENCES; GENERAL CIRCULATION MODELS; SENSITIVITY ANALYSIS; AIR-WATER INTERACTIONS; SOUTHERN OSCILLATION; ALBEDO; PACIFIC OCEAN; CLOUD COVER; HEAT FLUX; 540110; BASIC STUDIES
OSTI ID:
10106172
Research Organizations:
Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)
Country of Origin:
Germany
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0937-1060; Other: ON: DE95726896; TRN: DE94FN556
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
DEN
Size:
30 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Stockdale, T, Latif, M, Burgers, G, and Wolff, J O. Some sensitivities of a coupled ocean-atmosphere GCM. Germany: N. p., 1994. Web.
Stockdale, T, Latif, M, Burgers, G, & Wolff, J O. Some sensitivities of a coupled ocean-atmosphere GCM. Germany.
Stockdale, T, Latif, M, Burgers, G, and Wolff, J O. 1994. "Some sensitivities of a coupled ocean-atmosphere GCM." Germany.
@misc{etde_10106172,
title = {Some sensitivities of a coupled ocean-atmosphere GCM}
author = {Stockdale, T, Latif, M, Burgers, G, and Wolff, J O}
abstractNote = {A coupled ocean-atmosphere GCM is being developed for use in seasonal forecasting. As part of the development work, a number of experiments have been made to explore some of the sensitivities of the coupled model system. The overall heat balance of the tropics is found to be very sensitive to convective cloud cover. Adjusting the cloud parameterization to produce stable behaviour of the coupled model also leads to better agreement between model radiative fluxes and satellite data. A further sensitivity is seen to changes in low-level marine stratus, which is under-represented in the initial model experiments. An increase in this cloud in the coupled model produces a small improvement in both the global mean state and the phase of the east Pacific annual cycle. The computational expense of investigating such small changes is emphasized. An indication of model sensitivity to surface albedo is also presented. The sensitivity of the coupled GCM to initial conditions is investigated. The model is very sensitive, with tiny perturbations able to determine El Nino or non-El Nino conditions just six months later. This large sensitivity may be related to the relatively weak amplitude of the model ENSO cycle. (orig.)}
place = {Germany}
year = {1994}
month = {Feb}
}