The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations
Recent efforts to narrow the spread in equilibrium climate sensitivity (ECS) across global climate models have focused on identifying observationally based constraints, which are rooted in empirical correlations between ECS and biases in the models' present-day climate. This study reexamines on...
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ftcdlib:oai:escholarship.org/ark:/13030/qt6kh587vm 2023-05-15T18:24:56+02:00 The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations Negrón-Juárez, RI Riley, WJ Koven, CD Knox, RG Taylor, PG Chambers, JQ 9313 - 9331 2015-01-01 https://escholarship.org/uc/item/6kh587vm unknown eScholarship, University of California qt6kh587vm https://escholarship.org/uc/item/6kh587vm public Journal of Climate, vol 28, iss 23 Models and modeling Climate models General circulation models Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering article 2015 ftcdlib 2021-05-08T18:03:45Z Recent efforts to narrow the spread in equilibrium climate sensitivity (ECS) across global climate models have focused on identifying observationally based constraints, which are rooted in empirical correlations between ECS and biases in the models' present-day climate. This study reexamines one such constraint identified from CMIP3 models: the linkage between ECS and net top-of-the-atmosphere radiation biases in the Southern Hemisphere (SH). As previously documented, the intermodel spread in the ECS of CMIP3 models is linked to present-day cloud and net radiation biases over the midlatitude Southern Ocean, where higher cloud fraction in the present-day climate is associated with larger values of ECS. However, in this study, no physical explanation is found to support this relationship. Furthermore, it is shown here that this relationship disappears in CMIP5 models and is unique to a subset of CMIP models characterized by unrealistically bright present-day clouds in the SH subtropics. In view of this evidence, Southern Ocean cloud and net radiation biases appear inappropriate for providing observationally based constraints on ECS. Instead of the Southern Ocean, this study points to the stratocumulus-to-cumulus transition regions of the SH subtropical oceans as key to explaining the intermodel spread in the ECS of both CMIP3 and CMIP5 models. In these regions, ECS is linked to present-day cloud and net radiation biases with a plausible physical mechanism: models with brighter subtropical clouds in the present-day climate show greater ECS because 1) subtropical clouds dissipate with increasing CO2 concentrations in many models and 2) the dissipation of brighter clouds contributes to greater solar warming of the surface. Article in Journal/Newspaper Southern Ocean University of California: eScholarship Southern Ocean |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Models and modeling Climate models General circulation models Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
spellingShingle |
Models and modeling Climate models General circulation models Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering Negrón-Juárez, RI Riley, WJ Koven, CD Knox, RG Taylor, PG Chambers, JQ The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations |
topic_facet |
Models and modeling Climate models General circulation models Meteorology & Atmospheric Sciences Atmospheric Sciences Oceanography Geomatic Engineering |
description |
Recent efforts to narrow the spread in equilibrium climate sensitivity (ECS) across global climate models have focused on identifying observationally based constraints, which are rooted in empirical correlations between ECS and biases in the models' present-day climate. This study reexamines one such constraint identified from CMIP3 models: the linkage between ECS and net top-of-the-atmosphere radiation biases in the Southern Hemisphere (SH). As previously documented, the intermodel spread in the ECS of CMIP3 models is linked to present-day cloud and net radiation biases over the midlatitude Southern Ocean, where higher cloud fraction in the present-day climate is associated with larger values of ECS. However, in this study, no physical explanation is found to support this relationship. Furthermore, it is shown here that this relationship disappears in CMIP5 models and is unique to a subset of CMIP models characterized by unrealistically bright present-day clouds in the SH subtropics. In view of this evidence, Southern Ocean cloud and net radiation biases appear inappropriate for providing observationally based constraints on ECS. Instead of the Southern Ocean, this study points to the stratocumulus-to-cumulus transition regions of the SH subtropical oceans as key to explaining the intermodel spread in the ECS of both CMIP3 and CMIP5 models. In these regions, ECS is linked to present-day cloud and net radiation biases with a plausible physical mechanism: models with brighter subtropical clouds in the present-day climate show greater ECS because 1) subtropical clouds dissipate with increasing CO2 concentrations in many models and 2) the dissipation of brighter clouds contributes to greater solar warming of the surface. |
format |
Article in Journal/Newspaper |
author |
Negrón-Juárez, RI Riley, WJ Koven, CD Knox, RG Taylor, PG Chambers, JQ |
author_facet |
Negrón-Juárez, RI Riley, WJ Koven, CD Knox, RG Taylor, PG Chambers, JQ |
author_sort |
Negrón-Juárez, RI |
title |
The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations |
title_short |
The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations |
title_full |
The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations |
title_fullStr |
The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations |
title_full_unstemmed |
The rainfall sensitivity of tropical net primary production in CMIP5 Twentieth- and Twenty-First-Century simulations |
title_sort |
rainfall sensitivity of tropical net primary production in cmip5 twentieth- and twenty-first-century simulations |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/6kh587vm |
op_coverage |
9313 - 9331 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Journal of Climate, vol 28, iss 23 |
op_relation |
qt6kh587vm https://escholarship.org/uc/item/6kh587vm |
op_rights |
public |
_version_ |
1766205976014225408 |