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Title: Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations

Abstract

A negative extratropical shortwave cloud feedback driven by changes in cloud optical depth is a feature of global climate models (GCMs). A robust positive trend in observed liquid water path (LWP) over the last two decades across the warming Southern Ocean supports the negative shortwave cloud feedback predicted by GCMs. This feature has been proposed to be due to transitions from ice to liquid with warming. To gain insight into the shortwave cloud feedback we examine extratropical cyclone variability and the response of extratropical cyclones to transient warming in GCM simulations. Multi-Sensor Advanced Climatology Liquid Water Path (MAC-LWP) microwave observations of cyclone properties from the period 1992–2015 are contrasted with GCM simulations, with horizontal resolutions ranging from 7 km to hundreds of kilometers. We find that inter-cyclone variability in LWP in both observations and models is strongly driven by the moisture flux along the cyclone's warm conveyor belt (WCB). Stronger WCB moisture flux enhances the LWP within cyclones. This relationship is replicated in GCMs, although its strength varies substantially across models. It is found that more than 80 % of the enhancement in Southern Hemisphere (SH) extratropical cyclone LWP in GCMs in response to a transient 4 K warming canmore » be predicted based on the relationship between the WCB moisture flux and cyclone LWP in the historical climate and their change in moisture flux between the historical and warmed climates. Further, it is found that that the robust trend in cyclone LWP over the Southern Ocean in observations and GCMs is consistent with changes in the moisture flux. We propose two cloud feedbacks acting within extratropical cyclones: a negative feedback driven by Clausius–Clapeyron increasing water vapor path (WVP), which enhances the amount of water vapor available to be fluxed into the cyclone, and a feedback moderated by changes in the life cycle and vorticity of cyclones under warming, which changes the rate at which existing moisture is imported into the cyclone. Both terms contribute to increasing LWP within the cyclone. While changes in moisture flux predict cyclone LWP trends in the current climate and the majority of changes in LWP in transient warming simulations, a portion of the LWP increase in response to climate change that is unexplained by increasing moisture fluxes may be due to phase transitions. The variability in LWP within cyclone composites is examined to understand what cyclonic regimes the mixed-phase cloud feedback is relevant to. At a fixed WCB moisture flux cyclone LWP increases with increasing sea surface temperature (SST) in the half of the composite poleward of the low and decreases in the half equatorward of the low in both GCMs and observations. Cloud-top phase partitioning observed by the Atmospheric Infrared Sounder (AIRS) indicates that phase transitions may be driving increases in LWP in the poleward half of cyclones.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [5]; ORCiD logo [6]; ORCiD logo [7];  [8];  [9];  [4]; ORCiD logo [9]; ORCiD logo [10];  [10];  [11];  [4];  [4]; ORCiD logo [4]
  1. Univ. of Leeds (United Kingdom). Inst. of Climate and Atmospheric Sciences
  2. Univ. of Leeds (United Kingdom). Inst. of Climate and Atmospheric Sciences; Met Office, Exeter (United Kingdom)
  3. Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States)
  4. Met Office, Exeter (United Kingdom)
  5. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Cloud Processes Research and Modeling Group
  7. Japan Agency for Marine-Earth Science and Technology, Yokohama (Japan)
  8. Max Planck Inst. for Meteorology, Hamburg (Germany); Stockholm Univ. (Sweden). Dept. of Meteorology
  9. Univ. of Reading (United Kingdom). National Centre for Atmospheric Science-Climate. Dept. of Meteorology
  10. Météo-France, Toulouse (France). National Centre for Meteorological Research (CNRM)
  11. Royal Netherlands Meteorological Inst., De Bilt (Netherlands)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States); NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States); Japan Agency for Marine-Earth Science and Technology, Yokohama (Japan); Univ. of Leeds (United Kingdom); Met Office, Exeter (United Kingdom)
Sponsoring Org.:
USDOE; National Aeronautic and Space Administration (NASA); Japan Society for the Promotion of Science (JSPS); European Union (EU)
OSTI Identifier:
1502016
Report Number(s):
LLNL-JRNL-755200
Journal ID: ISSN 1680-7324; 942141
Grant/Contract Number:  
AC52-07NA27344; GG008658; 17H04856; 641727
Resource Type:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 19; Journal Issue: 2; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

McCoy, Daniel T., Field, Paul R., Elsaesser, Gregory S., Bodas-Salcedo, Alejandro, Kahn, Brian H., Zelinka, Mark D., Kodama, Chihiro, Mauritsen, Thorsten, Vanniere, Benoit, Roberts, Malcolm, Vidale, Pier L., Saint-Martin, David, Voldoire, Aurore, Haarsma, Rein, Hill, Adrian, Shipway, Ben, and Wilkinson, Jonathan. Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations. United States: N. p., 2019. Web. doi:10.5194/acp-19-1147-2019.
McCoy, Daniel T., Field, Paul R., Elsaesser, Gregory S., Bodas-Salcedo, Alejandro, Kahn, Brian H., Zelinka, Mark D., Kodama, Chihiro, Mauritsen, Thorsten, Vanniere, Benoit, Roberts, Malcolm, Vidale, Pier L., Saint-Martin, David, Voldoire, Aurore, Haarsma, Rein, Hill, Adrian, Shipway, Ben, & Wilkinson, Jonathan. Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations. United States. doi:10.5194/acp-19-1147-2019.
McCoy, Daniel T., Field, Paul R., Elsaesser, Gregory S., Bodas-Salcedo, Alejandro, Kahn, Brian H., Zelinka, Mark D., Kodama, Chihiro, Mauritsen, Thorsten, Vanniere, Benoit, Roberts, Malcolm, Vidale, Pier L., Saint-Martin, David, Voldoire, Aurore, Haarsma, Rein, Hill, Adrian, Shipway, Ben, and Wilkinson, Jonathan. Wed . "Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations". United States. doi:10.5194/acp-19-1147-2019. https://www.osti.gov/servlets/purl/1502016.
@article{osti_1502016,
title = {Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations},
author = {McCoy, Daniel T. and Field, Paul R. and Elsaesser, Gregory S. and Bodas-Salcedo, Alejandro and Kahn, Brian H. and Zelinka, Mark D. and Kodama, Chihiro and Mauritsen, Thorsten and Vanniere, Benoit and Roberts, Malcolm and Vidale, Pier L. and Saint-Martin, David and Voldoire, Aurore and Haarsma, Rein and Hill, Adrian and Shipway, Ben and Wilkinson, Jonathan},
abstractNote = {A negative extratropical shortwave cloud feedback driven by changes in cloud optical depth is a feature of global climate models (GCMs). A robust positive trend in observed liquid water path (LWP) over the last two decades across the warming Southern Ocean supports the negative shortwave cloud feedback predicted by GCMs. This feature has been proposed to be due to transitions from ice to liquid with warming. To gain insight into the shortwave cloud feedback we examine extratropical cyclone variability and the response of extratropical cyclones to transient warming in GCM simulations. Multi-Sensor Advanced Climatology Liquid Water Path (MAC-LWP) microwave observations of cyclone properties from the period 1992–2015 are contrasted with GCM simulations, with horizontal resolutions ranging from 7 km to hundreds of kilometers. We find that inter-cyclone variability in LWP in both observations and models is strongly driven by the moisture flux along the cyclone's warm conveyor belt (WCB). Stronger WCB moisture flux enhances the LWP within cyclones. This relationship is replicated in GCMs, although its strength varies substantially across models. It is found that more than 80 % of the enhancement in Southern Hemisphere (SH) extratropical cyclone LWP in GCMs in response to a transient 4 K warming can be predicted based on the relationship between the WCB moisture flux and cyclone LWP in the historical climate and their change in moisture flux between the historical and warmed climates. Further, it is found that that the robust trend in cyclone LWP over the Southern Ocean in observations and GCMs is consistent with changes in the moisture flux. We propose two cloud feedbacks acting within extratropical cyclones: a negative feedback driven by Clausius–Clapeyron increasing water vapor path (WVP), which enhances the amount of water vapor available to be fluxed into the cyclone, and a feedback moderated by changes in the life cycle and vorticity of cyclones under warming, which changes the rate at which existing moisture is imported into the cyclone. Both terms contribute to increasing LWP within the cyclone. While changes in moisture flux predict cyclone LWP trends in the current climate and the majority of changes in LWP in transient warming simulations, a portion of the LWP increase in response to climate change that is unexplained by increasing moisture fluxes may be due to phase transitions. The variability in LWP within cyclone composites is examined to understand what cyclonic regimes the mixed-phase cloud feedback is relevant to. At a fixed WCB moisture flux cyclone LWP increases with increasing sea surface temperature (SST) in the half of the composite poleward of the low and decreases in the half equatorward of the low in both GCMs and observations. Cloud-top phase partitioning observed by the Atmospheric Infrared Sounder (AIRS) indicates that phase transitions may be driving increases in LWP in the poleward half of cyclones.},
doi = {10.5194/acp-19-1147-2019},
journal = {Atmospheric Chemistry and Physics (Online)},
number = 2,
volume = 19,
place = {United States},
year = {2019},
month = {1}
}

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