The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios

Abstract Stable water isotopes are data‐rich tracers of the hydrological cycle, and, recently, the advent of isotope‐enabled climate models has allowed for investigations into the utility of water isotopes for tracking changes in the large‐scale atmospheric circulation. Among the suite of published...

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Autores principales:	Jun Hu, Sylvia Dee, Jesse Nusbaumer
Formato:	article
Lenguaje:	EN
Publicado:	American Geophysical Union (AGU) 2020
Materias:	Physical geography GB3-5030 Oceanography GC1-1581
Acceso en línea:	https://doaj.org/article/91306162d10c4eeca6a2696492544dd1
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spelling	oai:doaj.org-article:91306162d10c4eeca6a2696492544dd12021-11-15T14:20:26ZThe Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios1942-246610.1029/2020MS002163https://doaj.org/article/91306162d10c4eeca6a2696492544dd12020-08-01T00:00:00Zhttps://doi.org/10.1029/2020MS002163https://doaj.org/toc/1942-2466Abstract Stable water isotopes are data‐rich tracers of the hydrological cycle, and, recently, the advent of isotope‐enabled climate models has allowed for investigations into the utility of water isotopes for tracking changes in the large‐scale atmospheric circulation. Among the suite of published isotope‐enabled climate models, those with intermediate complexity offer the benefits of efficiency, allowing for long ensemble runs. However, the ability of these models to simulate the response to global warming with the same fidelity as state‐of‐the‐art models is questionable. Here we evaluate an intermediate complexity model, SPEEDY‐IER, in a high‐CO2 scenario and compare its performance to an Intergovernmental Panel on Climate Change (IPCC)‐class model, iCAM5. SPEEDY‐IER can generally simulate changes in tropical circulation, the weakening of the Walker circulation, and the narrowing of the deep tropics. A deeper investigation of water isotope fields indicates SPEEDY‐IER simulates qualitative trends in precipitation and vapor isotopes with fidelity, but it does not simulate amplitudes or spatial patterns of water isotope changes shown in iCAM5. This bias in SPEEDY‐IER is mainly due to its coarse resolution and simplified convection scheme. We then modify the model by introducing condensation and detrainment in intermediate convection levels; this modification successfully improves SPEEDY‐IER's simulation of water isotope fields, though the response of the Walker circulation to climate change is weakened. We demonstrate that evaluating water isotope fields reveals hidden biases in a climate model and guides improvements to the model's performance. Thus, the examination of water isotope fields and validation against available observations likely provides more stringent constraints for model physics.Jun HuSylvia DeeJesse NusbaumerAmerican Geophysical Union (AGU)articlePhysical geographyGB3-5030OceanographyGC1-1581ENJournal of Advances in Modeling Earth Systems, Vol 12, Iss 8, Pp n/a-n/a (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physical geography GB3-5030 Oceanography GC1-1581
spellingShingle	Physical geography GB3-5030 Oceanography GC1-1581 Jun Hu Sylvia Dee Jesse Nusbaumer The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios
description	Abstract Stable water isotopes are data‐rich tracers of the hydrological cycle, and, recently, the advent of isotope‐enabled climate models has allowed for investigations into the utility of water isotopes for tracking changes in the large‐scale atmospheric circulation. Among the suite of published isotope‐enabled climate models, those with intermediate complexity offer the benefits of efficiency, allowing for long ensemble runs. However, the ability of these models to simulate the response to global warming with the same fidelity as state‐of‐the‐art models is questionable. Here we evaluate an intermediate complexity model, SPEEDY‐IER, in a high‐CO2 scenario and compare its performance to an Intergovernmental Panel on Climate Change (IPCC)‐class model, iCAM5. SPEEDY‐IER can generally simulate changes in tropical circulation, the weakening of the Walker circulation, and the narrowing of the deep tropics. A deeper investigation of water isotope fields indicates SPEEDY‐IER simulates qualitative trends in precipitation and vapor isotopes with fidelity, but it does not simulate amplitudes or spatial patterns of water isotope changes shown in iCAM5. This bias in SPEEDY‐IER is mainly due to its coarse resolution and simplified convection scheme. We then modify the model by introducing condensation and detrainment in intermediate convection levels; this modification successfully improves SPEEDY‐IER's simulation of water isotope fields, though the response of the Walker circulation to climate change is weakened. We demonstrate that evaluating water isotope fields reveals hidden biases in a climate model and guides improvements to the model's performance. Thus, the examination of water isotope fields and validation against available observations likely provides more stringent constraints for model physics.
format	article
author	Jun Hu Sylvia Dee Jesse Nusbaumer
author_facet	Jun Hu Sylvia Dee Jesse Nusbaumer
author_sort	Jun Hu
title	The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios
title_short	The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios
title_full	The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios
title_fullStr	The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios
title_full_unstemmed	The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios
title_sort	role of isotope‐enabled gcm complexity in simulating tropical circulation changes in high‐co2 scenarios
publisher	American Geophysical Union (AGU)
publishDate	2020
url	https://doaj.org/article/91306162d10c4eeca6a2696492544dd1
work_keys_str_mv	AT junhu theroleofisotopeenabledgcmcomplexityinsimulatingtropicalcirculationchangesinhighco2scenarios AT sylviadee theroleofisotopeenabledgcmcomplexityinsimulatingtropicalcirculationchangesinhighco2scenarios AT jessenusbaumer theroleofisotopeenabledgcmcomplexityinsimulatingtropicalcirculationchangesinhighco2scenarios AT junhu roleofisotopeenabledgcmcomplexityinsimulatingtropicalcirculationchangesinhighco2scenarios AT sylviadee roleofisotopeenabledgcmcomplexityinsimulatingtropicalcirculationchangesinhighco2scenarios AT jessenusbaumer roleofisotopeenabledgcmcomplexityinsimulatingtropicalcirculationchangesinhighco2scenarios
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The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO2 Scenarios

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