Show simple item record

dc.contributor.authorGertler, Charles G.
dc.contributor.authorO’Gorman, Paul A.
dc.date.accessioned2020-03-31T12:52:19Z
dc.date.available2020-03-31T12:52:19Z
dc.date.issued2019-02-19
dc.identifier.issn0027-8424
dc.identifier.issn1091-6490
dc.identifier.urihttps://hdl.handle.net/1721.1/124441
dc.description.abstractThe circulation of the Northern Hemisphere extratropical troposphere has changed over recent decades, with marked decreases in extratropical cyclone activity and eddy kinetic energy (EKE) in summer and increases in the fraction of precipitation that is convective in all seasons. Decreasing EKE in summer is partly explained by a weakening meridional temperature gradient, but changes in vertical temperature gradients and increasing moisture also affect the mean available potential energy (MAPE), which is the energetic reservoir from which extratropical cyclones draw. Furthermore, the relation of changes in mean thermal structure and moisture to changes in convection associated with extratropical cyclones is poorly understood. Here we calculate trends in MAPE for the Northern extratropics in summer over the years 1979–2017, and we decompose MAPE into both convective and nonconvective components. Nonconvective MAPE decreased over this period, consistent with decreases in EKE and extratropical cyclone activity, but convective MAPE increased, implying an increase in the energy available to convection. Calculations with idealized atmospheres indicate that nonconvective and convective MAPE both increase with increasing mean surface temperature and decrease with decreasing meridional surface temperature gradient, but convective MAPE is relatively more sensitive to the increase in mean surface temperature. These results connect changes in the atmospheric mean state with changes in both large-scale and convective circulations, and they suggest that extratropical cyclones can weaken even as their associated convection becomes more energetic.en_US
dc.description.sponsorshipNational Science Foundation (U.S.). Graduate Research Fellowship (Grant 1122374)en_US
dc.description.sponsorshipNational Science Foundation (U.S.) (Grant AGS 1552195)en_US
dc.description.sponsorshipNational Science Foundation (U.S.) (Grant AGS 1749986)en_US
dc.language.isoen
dc.publisherProceedings of the National Academy of Sciencesen_US
dc.relation.isversionof10.1073/pnas.1812312116en_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.sourcePNASen_US
dc.subjectMultidisciplinaryen_US
dc.titleChanging available energy for extratropical cyclones and associated convection in Northern Hemisphere summeren_US
dc.typeArticleen_US
dc.identifier.citationGertler, Charles G. and Paul A. O’Gorman. "Changing available energy for extratropical cyclones and associated convection in Northern Hemisphere summer." Proceedings of the National Academy of Sciences of the United States of America 116 (2019): 4105-4110 © 2019 The Author(s)en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciencesen_US
dc.relation.journalProceedings of the National Academy of Sciences of the United States of Americaen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dc.date.updated2020-02-11T13:48:46Z
dspace.date.submission2020-02-11T13:48:51Z
mit.journal.volume116en_US
mit.journal.issue10en_US
mit.licensePUBLISHER_POLICY


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record