Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies
The Eliassen–Palm (EP) flux is an important diagnostic for wave propagation and wave–mean flow interaction in the atmosphere. Here, two moist formulations of the EP flux are compared with the traditional dry EP flux, and their links to the surface westerlies are analyzed using reanalysis data and si...
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| Format: | Article |
| Language: | en_US |
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American Meteorological Society
2017
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| Online Access: | http://hdl.handle.net/1721.1/111124 https://orcid.org/0000-0003-4492-9914 https://orcid.org/0000-0003-1748-0816 |
| _version_ | 1811068489860907008 |
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| author | Dwyer, John G O'Gorman, Paul |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Dwyer, John G O'Gorman, Paul |
| author_sort | Dwyer, John G |
| collection | MIT |
| description | The Eliassen–Palm (EP) flux is an important diagnostic for wave propagation and wave–mean flow interaction in the atmosphere. Here, two moist formulations of the EP flux are compared with the traditional dry EP flux, and their links to the surface westerlies are analyzed using reanalysis data and simulations with GCMs. The first moist formulation of the EP flux modifies only the static stability to account for latent heat release by eddies, while the second moist formulation simply replaces all potential temperatures with equivalent potential temperatures. For reanalysis data, the peak upward EP flux in the lower troposphere is farther equatorward and stronger when the moist formulations are used, with greater changes for the second moist formulation. The moist formulations have the advantage of giving a closer relationship over the seasonal cycle between the latitudes of the peak surface westerlies and the peak upward EP flux. In simulations with a comprehensive GCM, the dry and moist upward EP fluxes shift poleward by a similar amount as the climate warms. In simulations over a wider range of climates with an idealized GCM, the surface westerlies can shift both poleward and equatorward with warming, and they are influenced by an anomalous region of dry EP flux divergence near the subtropical jet. Using moist EP fluxes weakens this anomalous divergence in the idealized GCM simulations, and the shifts in the surface westerlies can then be understood through changes in the preference for equatorward or poleward wave propagation. |
| first_indexed | 2024-09-23T07:56:44Z |
| format | Article |
| id | mit-1721.1/111124 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T07:56:44Z |
| publishDate | 2017 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1111242024-06-26T15:21:14Z Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies Dwyer, John G O'Gorman, Paul Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Dwyer, John G O'Gorman, Paul The Eliassen–Palm (EP) flux is an important diagnostic for wave propagation and wave–mean flow interaction in the atmosphere. Here, two moist formulations of the EP flux are compared with the traditional dry EP flux, and their links to the surface westerlies are analyzed using reanalysis data and simulations with GCMs. The first moist formulation of the EP flux modifies only the static stability to account for latent heat release by eddies, while the second moist formulation simply replaces all potential temperatures with equivalent potential temperatures. For reanalysis data, the peak upward EP flux in the lower troposphere is farther equatorward and stronger when the moist formulations are used, with greater changes for the second moist formulation. The moist formulations have the advantage of giving a closer relationship over the seasonal cycle between the latitudes of the peak surface westerlies and the peak upward EP flux. In simulations with a comprehensive GCM, the dry and moist upward EP fluxes shift poleward by a similar amount as the climate warms. In simulations over a wider range of climates with an idealized GCM, the surface westerlies can shift both poleward and equatorward with warming, and they are influenced by an anomalous region of dry EP flux divergence near the subtropical jet. Using moist EP fluxes weakens this anomalous divergence in the idealized GCM simulations, and the shifts in the surface westerlies can then be understood through changes in the preference for equatorward or poleward wave propagation. National Science Foundation (U.S.) (Grant AGS-1148594) 2017-09-05T17:29:55Z 2017-09-05T17:29:55Z 2017-01 2016-10 Article http://purl.org/eprint/type/JournalArticle 0022-4928 1520-0469 http://hdl.handle.net/1721.1/111124 Dwyer, John G., and O’Gorman, Paul A. “Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies.” Journal of the Atmospheric Sciences 74, 2 (February 2017): 513–530 © 2017 American Meteorological Society https://orcid.org/0000-0003-4492-9914 https://orcid.org/0000-0003-1748-0816 en_US http://dx.doi.org/10.1175/jas-d-16-0111.1 Journal of the Atmospheric Sciences Article 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. application/pdf American Meteorological Society American Meteorological Society |
| spellingShingle | Dwyer, John G O'Gorman, Paul Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies |
| title | Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies |
| title_full | Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies |
| title_fullStr | Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies |
| title_full_unstemmed | Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies |
| title_short | Moist Formulations of the Eliassen–Palm Flux and Their Connection to the Surface Westerlies |
| title_sort | moist formulations of the eliassen palm flux and their connection to the surface westerlies |
| url | http://hdl.handle.net/1721.1/111124 https://orcid.org/0000-0003-4492-9914 https://orcid.org/0000-0003-1748-0816 |
| work_keys_str_mv | AT dwyerjohng moistformulationsoftheeliassenpalmfluxandtheirconnectiontothesurfacewesterlies AT ogormanpaul moistformulationsoftheeliassenpalmfluxandtheirconnectiontothesurfacewesterlies |