Heat Uptake and the Thermohaline Circulation in the Community Climate System Model, Version 2Source: Journal of Climate:;2004:;volume( 017 ):;issue: 020::page 4058DOI: 10.1175/1520-0442(2004)017<4058:HUATTC>2.0.CO;2Publisher: American Meteorological Society
Abstract: Ocean heat uptake and the thermohaline circulation are analyzed in present-day control, 1% increasing CO2, and doubled CO2 runs of the Community Climate System Model, version 2 (CCSM2). It is concluded that the observed 40-yr trend in the global heat content to 300 m, found by Levitus et al., is somewhat larger than the natural variability in the CCSM2 control run. The observed 40-yr trend in the global heat content down to a depth of 3 km is much closer to trends found in the control run and is not so clearly separated from the natural model variability. It is estimated that, in a 0.7% increasing CO2 scenario that approximates the effect of increasing greenhouse gases between 1958 and 1998, the CCSM2 40-yr trend in the global heat content to 300 m is about the same as the observed value. This gives support for the CCSM2 climate sensitivity, which is 2.2°C. Both the maximum of the meridional overturning streamfunction and the vertical flow across 1-km depth between 60° and 65°N decrease monotonically during the 1% CO2 run. However, the reductions are quite modest, being 3 and 2 Sv, respectively, when CO2 has quadrupled. The reason for this is that the surface potential density in the northern North Atlantic decreases steadily throughout the 1% CO2 run. In the latter part of the doubled CO2 run, the meridional overturning streamfunction recovers in strength back toward its value in the control run, but the deep-water formation rate across 1-km depth between 60° and 65°N remains at 85% of the control run value. The maximum northward heat transport at 22°N is governed by the maximum of the overturning, but the transport poleward of 62°N appears to be independent of the deep-water formation rate.
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contributor author | Gent, Peter R. | |
contributor author | Danabasoglu, Gokhan | |
date accessioned | 2017-06-09T16:25:10Z | |
date available | 2017-06-09T16:25:10Z | |
date copyright | 2004/10/01 | |
date issued | 2004 | |
identifier issn | 0894-8755 | |
identifier other | ams-6751.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4208967 | |
description abstract | Ocean heat uptake and the thermohaline circulation are analyzed in present-day control, 1% increasing CO2, and doubled CO2 runs of the Community Climate System Model, version 2 (CCSM2). It is concluded that the observed 40-yr trend in the global heat content to 300 m, found by Levitus et al., is somewhat larger than the natural variability in the CCSM2 control run. The observed 40-yr trend in the global heat content down to a depth of 3 km is much closer to trends found in the control run and is not so clearly separated from the natural model variability. It is estimated that, in a 0.7% increasing CO2 scenario that approximates the effect of increasing greenhouse gases between 1958 and 1998, the CCSM2 40-yr trend in the global heat content to 300 m is about the same as the observed value. This gives support for the CCSM2 climate sensitivity, which is 2.2°C. Both the maximum of the meridional overturning streamfunction and the vertical flow across 1-km depth between 60° and 65°N decrease monotonically during the 1% CO2 run. However, the reductions are quite modest, being 3 and 2 Sv, respectively, when CO2 has quadrupled. The reason for this is that the surface potential density in the northern North Atlantic decreases steadily throughout the 1% CO2 run. In the latter part of the doubled CO2 run, the meridional overturning streamfunction recovers in strength back toward its value in the control run, but the deep-water formation rate across 1-km depth between 60° and 65°N remains at 85% of the control run value. The maximum northward heat transport at 22°N is governed by the maximum of the overturning, but the transport poleward of 62°N appears to be independent of the deep-water formation rate. | |
publisher | American Meteorological Society | |
title | Heat Uptake and the Thermohaline Circulation in the Community Climate System Model, Version 2 | |
type | Journal Paper | |
journal volume | 17 | |
journal issue | 20 | |
journal title | Journal of Climate | |
identifier doi | 10.1175/1520-0442(2004)017<4058:HUATTC>2.0.CO;2 | |
journal fristpage | 4058 | |
journal lastpage | 4069 | |
tree | Journal of Climate:;2004:;volume( 017 ):;issue: 020 | |
contenttype | Fulltext |