Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models
Increasing optical depth poleward of 45° is a robust response to warming in global climate models. Much of this cloud optical depth increase has been hypothesized to be due to transitions from ice‐dominated to liquid‐dominated mixed‐phase cloud. In this study, the importance of liquid‐ice partitioni...
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ftimperialcol:oai:spiral.imperial.ac.uk:10044/1/76096 2023-05-15T18:25:13+02:00 Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models McCoy, DT Hartmann, DL Zelinka, MD Ceppi, P Grosvenor, DP 2015-08-19 http://hdl.handle.net/10044/1/76096 https://doi.org/10.1002/2015JD023603 English eng American Geophysical Union Journal of Geophysical Research: Atmospheres 2169-897X http://hdl.handle.net/10044/1/76096 doi:10.1002/2015JD023603 ©2015. American Geophysical Union. All Rights Reserved. 9554 9539 Science & Technology Physical Sciences Meteorology & Atmospheric Sciences climate Southern Ocean feedbacks mixed phase clouds STRATIFORM CLOUDS LAYER CLOUD WATER STRATOCUMULUS SIMULATIONS MULTIMODEL TRANSITION SATELLITE COVER CMIP5 Journal Article 2015 ftimperialcol https://doi.org/10.1002/2015JD023603 2020-03-12T23:38:08Z Increasing optical depth poleward of 45° is a robust response to warming in global climate models. Much of this cloud optical depth increase has been hypothesized to be due to transitions from ice‐dominated to liquid‐dominated mixed‐phase cloud. In this study, the importance of liquid‐ice partitioning for the optical depth feedback is quantified for 19 Coupled Model Intercomparison Project Phase 5 models. All models show a monotonic partitioning of ice and liquid as a function of temperature, but the temperature at which ice and liquid are equally mixed (the glaciation temperature) varies by as much as 40 K across models. Models that have a higher glaciation temperature are found to have a smaller climatological liquid water path (LWP) and condensed water path and experience a larger increase in LWP as the climate warms. The ice‐liquid partitioning curve of each model may be used to calculate the response of LWP to warming. It is found that the repartitioning between ice and liquid in a warming climate contributes at least 20% to 80% of the increase in LWP as the climate warms, depending on model. Intermodel differences in the climatological partitioning between ice and liquid are estimated to contribute at least 20% to the intermodel spread in the high‐latitude LWP response in the mixed‐phase region poleward of 45°S. It is hypothesized that a more thorough evaluation and constraint of global climate model mixed‐phase cloud parameterizations and validation of the total condensate and ice‐liquid apportionment against observations will yield a substantial reduction in model uncertainty in the high‐latitude cloud response to warming. Article in Journal/Newspaper Southern Ocean Imperial College London: Spiral Southern Ocean Journal of Geophysical Research: Atmospheres 120 18 9539 9554 |
institution |
Open Polar |
collection |
Imperial College London: Spiral |
op_collection_id |
ftimperialcol |
language |
English |
topic |
Science & Technology Physical Sciences Meteorology & Atmospheric Sciences climate Southern Ocean feedbacks mixed phase clouds STRATIFORM CLOUDS LAYER CLOUD WATER STRATOCUMULUS SIMULATIONS MULTIMODEL TRANSITION SATELLITE COVER CMIP5 |
spellingShingle |
Science & Technology Physical Sciences Meteorology & Atmospheric Sciences climate Southern Ocean feedbacks mixed phase clouds STRATIFORM CLOUDS LAYER CLOUD WATER STRATOCUMULUS SIMULATIONS MULTIMODEL TRANSITION SATELLITE COVER CMIP5 McCoy, DT Hartmann, DL Zelinka, MD Ceppi, P Grosvenor, DP Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models |
topic_facet |
Science & Technology Physical Sciences Meteorology & Atmospheric Sciences climate Southern Ocean feedbacks mixed phase clouds STRATIFORM CLOUDS LAYER CLOUD WATER STRATOCUMULUS SIMULATIONS MULTIMODEL TRANSITION SATELLITE COVER CMIP5 |
description |
Increasing optical depth poleward of 45° is a robust response to warming in global climate models. Much of this cloud optical depth increase has been hypothesized to be due to transitions from ice‐dominated to liquid‐dominated mixed‐phase cloud. In this study, the importance of liquid‐ice partitioning for the optical depth feedback is quantified for 19 Coupled Model Intercomparison Project Phase 5 models. All models show a monotonic partitioning of ice and liquid as a function of temperature, but the temperature at which ice and liquid are equally mixed (the glaciation temperature) varies by as much as 40 K across models. Models that have a higher glaciation temperature are found to have a smaller climatological liquid water path (LWP) and condensed water path and experience a larger increase in LWP as the climate warms. The ice‐liquid partitioning curve of each model may be used to calculate the response of LWP to warming. It is found that the repartitioning between ice and liquid in a warming climate contributes at least 20% to 80% of the increase in LWP as the climate warms, depending on model. Intermodel differences in the climatological partitioning between ice and liquid are estimated to contribute at least 20% to the intermodel spread in the high‐latitude LWP response in the mixed‐phase region poleward of 45°S. It is hypothesized that a more thorough evaluation and constraint of global climate model mixed‐phase cloud parameterizations and validation of the total condensate and ice‐liquid apportionment against observations will yield a substantial reduction in model uncertainty in the high‐latitude cloud response to warming. |
format |
Article in Journal/Newspaper |
author |
McCoy, DT Hartmann, DL Zelinka, MD Ceppi, P Grosvenor, DP |
author_facet |
McCoy, DT Hartmann, DL Zelinka, MD Ceppi, P Grosvenor, DP |
author_sort |
McCoy, DT |
title |
Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models |
title_short |
Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models |
title_full |
Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models |
title_fullStr |
Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models |
title_full_unstemmed |
Mixed-phase cloud physics and Southern Ocean cloud feedback in climate models |
title_sort |
mixed-phase cloud physics and southern ocean cloud feedback in climate models |
publisher |
American Geophysical Union |
publishDate |
2015 |
url |
http://hdl.handle.net/10044/1/76096 https://doi.org/10.1002/2015JD023603 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
9554 9539 |
op_relation |
Journal of Geophysical Research: Atmospheres 2169-897X http://hdl.handle.net/10044/1/76096 doi:10.1002/2015JD023603 |
op_rights |
©2015. American Geophysical Union. All Rights Reserved. |
op_doi |
https://doi.org/10.1002/2015JD023603 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
120 |
container_issue |
18 |
container_start_page |
9539 |
op_container_end_page |
9554 |
_version_ |
1766206498922299392 |