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Title: Improved atmosphere-ocean coupled modeling in the tropics for climate prediction

Abstract

We investigated the initial development of the double ITCZ in the Community Climate System Model (CCSM Version 3) in the central Pacific. Starting from a resting initial condition of the ocean in January, the model developed a warm bias of sea-surface temperature (SST) in the central Pacific from 5oS to 10oS in the first three months. We found this initial bias to be caused by excessive surface shortwave radiation that is also present in the standalone atmospheric model. The initial bias is further amplified by biases in both surface latent heat flux and horizontal heat transport in the upper ocean. These biases are caused by the responses of surface winds to SST bias and the thermocline structure to surface wind curls. We also showed that the warming biases in surface solar radiation and latent heat fluxes are seasonally offset by cooling biases from reduced solar radiation after the austral summer due to cloud responses and in the austral fall due to enhanced evaporation when the maximum SST is closest to the equator. The warming biases from the dynamic heat transport by ocean currents however stay throughout all seasons once they are developed, which are eventually balanced by enhanced energy exchangemore » and penetration of solar radiation below the mixed layer. Our results also showed that the equatorial cold tongue develops after the warm biases in the south central Pacific, and the overestimation of surface shortwave radiation recurs in the austral summer in each year.« less

Authors:
 [1]
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  1. State Univ. of New York (SUNY), Stony Brook, NY (United States)
Publication Date:
Research Org.:
State Univ. of New York, Stony Brook, NY (United States). The Research Foundation
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1166909
Report Number(s):
DE-FG02-07ER64444_44331_A_10
DOE Contract Number:
FG02-07ER64444
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Climate models; double ITCZ

Citation Formats

Zhang, Minghua. Improved atmosphere-ocean coupled modeling in the tropics for climate prediction. United States: N. p., 2015. Web. doi:10.2172/1166909.
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Zhang, Minghua. Improved atmosphere-ocean coupled modeling in the tropics for climate prediction. United States. doi:10.2172/1166909.
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Zhang, Minghua. Thu . "Improved atmosphere-ocean coupled modeling in the tropics for climate prediction". United States. doi:10.2172/1166909. https://www.osti.gov/servlets/purl/1166909.
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@article{osti_1166909,
title = {Improved atmosphere-ocean coupled modeling in the tropics for climate prediction},
author = {Zhang, Minghua},
abstractNote = {We investigated the initial development of the double ITCZ in the Community Climate System Model (CCSM Version 3) in the central Pacific. Starting from a resting initial condition of the ocean in January, the model developed a warm bias of sea-surface temperature (SST) in the central Pacific from 5oS to 10oS in the first three months. We found this initial bias to be caused by excessive surface shortwave radiation that is also present in the standalone atmospheric model. The initial bias is further amplified by biases in both surface latent heat flux and horizontal heat transport in the upper ocean. These biases are caused by the responses of surface winds to SST bias and the thermocline structure to surface wind curls. We also showed that the warming biases in surface solar radiation and latent heat fluxes are seasonally offset by cooling biases from reduced solar radiation after the austral summer due to cloud responses and in the austral fall due to enhanced evaporation when the maximum SST is closest to the equator. The warming biases from the dynamic heat transport by ocean currents however stay throughout all seasons once they are developed, which are eventually balanced by enhanced energy exchange and penetration of solar radiation below the mixed layer. Our results also showed that the equatorial cold tongue develops after the warm biases in the south central Pacific, and the overestimation of surface shortwave radiation recurs in the austral summer in each year.},
doi = {10.2172/1166909},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 01 00:00:00 EST 2015},
month = {Thu Jan 01 00:00:00 EST 2015}
}
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DOI:  10.2172/1166909
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