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Title: An Ensemble Covariance Framework for Quantifying Forced Climate Variability and Its Time of Emergence

Abstract

Climate variability and its response to increasing greenhouse gases are important considerations for impacts and adaptation. Modeling studies commonly assess projected changes in variability in terms of changes in the variance of climate variables. Despite the distant and impactful covariations that climate variables can exhibit, the covariance response has received much less attention. Here, a novel ensemble framework is developed that facilitates a unified assessment of the response of the regional variances and covariances of a climate variable to imposed external forcings and their time of emergence from an unforced climate state. Illustrating the framework, the response of variability and covariability of land and ocean temperatures is assessed in the Community Earth System Model Large Ensemble under historical and RCP8.5 forcing. The results reveal that land temperature variance emerges from its preindustrial state in the 1950s and, by the end of the twenty-first century, grows to 1.5 times its preindustrial level. Demonstrating the importance of covariances for variability projections, the covariance between land and ocean temperature is considerably enhanced by 2100, reaching 1.4 times its preindustrial estimate. The framework is also applied to assess changes in monthly temperature variability associated with the Arctic region and the Northern Hemisphere midlatitudes. Consistentmore » with previous studies and coinciding with sea ice loss, Arctic temperature variance decreases in most months, emerging from its preindustrial state in the late twentieth century. Overall, these results demonstrate the utility of the framework in enabling a comprehensive assessment of variability and its response to external climate forcings.« less

Authors:
ORCiD logo [1];  [2];  [1];  [3]
  1. Department of Atmospheric and Oceanic Sciences, and Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado
  2. Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado
  3. National Center for Atmospheric Research, Boulder, Colorado
Publication Date:
Research Org.:
University Corporation for Atmospheric Research, Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1435389
Alternate Identifier(s):
OSTI ID: 1541850
Grant/Contract Number:  
FC02-97ER62402
Resource Type:
Published Article
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Name: Journal of Climate Journal Volume: 31 Journal Issue: 10; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Meteorology & Atmospheric Sciences

Citation Formats

Yettella, Vineel, Weiss, Jeffrey B., Kay, Jennifer E., and Pendergrass, Angeline G. An Ensemble Covariance Framework for Quantifying Forced Climate Variability and Its Time of Emergence. United States: N. p., 2018. Web. doi:10.1175/JCLI-D-17-0719.1.
Yettella, Vineel, Weiss, Jeffrey B., Kay, Jennifer E., & Pendergrass, Angeline G. An Ensemble Covariance Framework for Quantifying Forced Climate Variability and Its Time of Emergence. United States. doi:10.1175/JCLI-D-17-0719.1.
Yettella, Vineel, Weiss, Jeffrey B., Kay, Jennifer E., and Pendergrass, Angeline G. Tue . "An Ensemble Covariance Framework for Quantifying Forced Climate Variability and Its Time of Emergence". United States. doi:10.1175/JCLI-D-17-0719.1.
@article{osti_1435389,
title = {An Ensemble Covariance Framework for Quantifying Forced Climate Variability and Its Time of Emergence},
author = {Yettella, Vineel and Weiss, Jeffrey B. and Kay, Jennifer E. and Pendergrass, Angeline G.},
abstractNote = {Climate variability and its response to increasing greenhouse gases are important considerations for impacts and adaptation. Modeling studies commonly assess projected changes in variability in terms of changes in the variance of climate variables. Despite the distant and impactful covariations that climate variables can exhibit, the covariance response has received much less attention. Here, a novel ensemble framework is developed that facilitates a unified assessment of the response of the regional variances and covariances of a climate variable to imposed external forcings and their time of emergence from an unforced climate state. Illustrating the framework, the response of variability and covariability of land and ocean temperatures is assessed in the Community Earth System Model Large Ensemble under historical and RCP8.5 forcing. The results reveal that land temperature variance emerges from its preindustrial state in the 1950s and, by the end of the twenty-first century, grows to 1.5 times its preindustrial level. Demonstrating the importance of covariances for variability projections, the covariance between land and ocean temperature is considerably enhanced by 2100, reaching 1.4 times its preindustrial estimate. The framework is also applied to assess changes in monthly temperature variability associated with the Arctic region and the Northern Hemisphere midlatitudes. Consistent with previous studies and coinciding with sea ice loss, Arctic temperature variance decreases in most months, emerging from its preindustrial state in the late twentieth century. Overall, these results demonstrate the utility of the framework in enabling a comprehensive assessment of variability and its response to external climate forcings.},
doi = {10.1175/JCLI-D-17-0719.1},
journal = {Journal of Climate},
number = 10,
volume = 31,
place = {United States},
year = {2018},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1175/JCLI-D-17-0719.1

Citation Metrics:
Cited by: 1 work
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