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Title: Tropical response to increased CO sub 2 in a GCM with a simple mixed layer ocean: Similarities to an observed Pacific warm event

Abstract

A version of the NCAR Community Climate Model (CCM), a global spectral atmospheric general circulation model, is coupled to a simple ocean mixed layer model with fixed depth. This mixed layer model is a simple slab of water that crudely accounts for seasonal heat storage but has no dynamics (e.g., advection, diffusion or upwelling). As a result, tropical sea surface temperatures (SSTs) produced by the simple mixed layer are warmer than observed in the equatorial tropics on the order of 1{degree}-2{degree}C. However, this uniform longitudinal warming is not associated with uniform longitudinal increases of tropical precipitation. Greatest area-averaged increases of precipitation occur in the tropical Pacific, while decreases of area-averaged precipitation are noted in the Asian monsoon regions. This is attributed to a disruption of the east-west circulation between the Pacific and Indian sectors similar to that observed during Pacific Warm Events. Accordingly, a number of the features of the model response to increased CO{sub 2} resemble those of a Warm Event. These include, for example, westerly upper-level wind anomalies in the subtropics of the pacific in both hemispheres, westerly similarities, it is emphasized that the real climate system may respond differently to an increase in CO{sub 2} due tomore » the importance of tropical ocean dynamics that are not included in the present simple mixed-layer ocean model. The next step in the modeling hierarchy, an ocean GCM coupled to the NCAR CCM, will show how the response in the tropics, documented here for SSTs determined only by surface energy balance and crude ocean heat storage, may be affected by the addition of ocean dynamics.« less

Authors:
;  [1]
  1. National Center for Atmospheric Research, Boulder, CO (USA)
Publication Date:
OSTI Identifier:
7017961
Resource Type:
Journal Article
Journal Name:
Monthly Weather Review; (USA)
Additional Journal Information:
Journal Volume: 114; Journal ID: ISSN 0027-0644
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CARBON DIOXIDE; CLIMATE MODELS; ENVIRONMENTAL IMPACTS; GENERAL CIRCULATION MODELS; SURFACE WATERS; AMBIENT TEMPERATURE; TROPICAL REGIONS; CLIMATES; ATMOSPHERIC CIRCULATION; ATMOSPHERIC PRECIPITATIONS; ENERGY BALANCE; INDIAN OCEAN; PACIFIC OCEAN; SEAS; WIND; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; MATHEMATICAL MODELS; OXIDES; OXYGEN COMPOUNDS; 540120* - Environment, Atmospheric- Chemicals Monitoring & Transport- (1990-); 540310 - Environment, Aquatic- Basic Studies- (1990-)

Citation Formats

Meehl, G A, and Washington, W M. Tropical response to increased CO sub 2 in a GCM with a simple mixed layer ocean: Similarities to an observed Pacific warm event. United States: N. p., 1986. Web. doi:10.1175/1520-0493(1986)114<0667:TRTICI>2.0.CO;2.
Meehl, G A, & Washington, W M. Tropical response to increased CO sub 2 in a GCM with a simple mixed layer ocean: Similarities to an observed Pacific warm event. United States. https://doi.org/10.1175/1520-0493(1986)114<0667:TRTICI>2.0.CO;2
Meehl, G A, and Washington, W M. 1986. "Tropical response to increased CO sub 2 in a GCM with a simple mixed layer ocean: Similarities to an observed Pacific warm event". United States. https://doi.org/10.1175/1520-0493(1986)114<0667:TRTICI>2.0.CO;2.
@article{osti_7017961,
title = {Tropical response to increased CO sub 2 in a GCM with a simple mixed layer ocean: Similarities to an observed Pacific warm event},
author = {Meehl, G A and Washington, W M},
abstractNote = {A version of the NCAR Community Climate Model (CCM), a global spectral atmospheric general circulation model, is coupled to a simple ocean mixed layer model with fixed depth. This mixed layer model is a simple slab of water that crudely accounts for seasonal heat storage but has no dynamics (e.g., advection, diffusion or upwelling). As a result, tropical sea surface temperatures (SSTs) produced by the simple mixed layer are warmer than observed in the equatorial tropics on the order of 1{degree}-2{degree}C. However, this uniform longitudinal warming is not associated with uniform longitudinal increases of tropical precipitation. Greatest area-averaged increases of precipitation occur in the tropical Pacific, while decreases of area-averaged precipitation are noted in the Asian monsoon regions. This is attributed to a disruption of the east-west circulation between the Pacific and Indian sectors similar to that observed during Pacific Warm Events. Accordingly, a number of the features of the model response to increased CO{sub 2} resemble those of a Warm Event. These include, for example, westerly upper-level wind anomalies in the subtropics of the pacific in both hemispheres, westerly similarities, it is emphasized that the real climate system may respond differently to an increase in CO{sub 2} due to the importance of tropical ocean dynamics that are not included in the present simple mixed-layer ocean model. The next step in the modeling hierarchy, an ocean GCM coupled to the NCAR CCM, will show how the response in the tropics, documented here for SSTs determined only by surface energy balance and crude ocean heat storage, may be affected by the addition of ocean dynamics.},
doi = {10.1175/1520-0493(1986)114<0667:TRTICI>2.0.CO;2},
url = {https://www.osti.gov/biblio/7017961}, journal = {Monthly Weather Review; (USA)},
issn = {0027-0644},
number = ,
volume = 114,
place = {United States},
year = {1986},
month = {4}
}