The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land
Simulations with climate models show a land–ocean contrast in the response of P − E (precipitation minus evaporation or evapotranspiration) to global warming, with larger changes over ocean than over land. The changes over ocean broadly follow a simple thermodynamic scaling of the atmospheric moistu...
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| Format: | Article |
| Language: | en_US |
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American Meteorological Society
2016
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| Online Access: | http://hdl.handle.net/1721.1/102264 https://orcid.org/0000-0003-1748-0816 |
| _version_ | 1811098230878896128 |
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| author | Byrne, Michael P. 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 Byrne, Michael P. O'Gorman, Paul |
| author_sort | Byrne, Michael P. |
| collection | MIT |
| description | Simulations with climate models show a land–ocean contrast in the response of P − E (precipitation minus evaporation or evapotranspiration) to global warming, with larger changes over ocean than over land. The changes over ocean broadly follow a simple thermodynamic scaling of the atmospheric moisture convergence: the so-called “wet-get-wetter, dry-get-drier” mechanism. Over land, however, the simple scaling fails to give any regions with decreases in P − E, and it overestimates increases in P − E compared to the simulations. Changes in circulation cause deviations from the simple scaling, but they are not sufficient to explain this systematic moist bias. It is shown here that horizontal gradients of changes in temperature and fractional changes in relative humidity, not accounted for in the simple scaling, are important over land and high-latitude oceans. An extended scaling that incorporates these gradients is shown to better capture the response of P − E over land, including a smaller increase in global-mean runoff and several regions with decreases in P − E. In the zonal mean over land, the gradient terms lead to a robust drying tendency at almost all latitudes. This drying tendency is shown to relate, in part, to the polar amplification of warming in the Northern Hemisphere, and to the amplified warming over continental interiors and on the eastern side of midlatitude continents. |
| first_indexed | 2024-09-23T17:11:58Z |
| format | Article |
| id | mit-1721.1/102264 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T17:11:58Z |
| publishDate | 2016 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1022642024-05-15T05:35:34Z The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land Byrne, Michael P. O'Gorman, Paul Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences O'Gorman, Paul Ambrose Simulations with climate models show a land–ocean contrast in the response of P − E (precipitation minus evaporation or evapotranspiration) to global warming, with larger changes over ocean than over land. The changes over ocean broadly follow a simple thermodynamic scaling of the atmospheric moisture convergence: the so-called “wet-get-wetter, dry-get-drier” mechanism. Over land, however, the simple scaling fails to give any regions with decreases in P − E, and it overestimates increases in P − E compared to the simulations. Changes in circulation cause deviations from the simple scaling, but they are not sufficient to explain this systematic moist bias. It is shown here that horizontal gradients of changes in temperature and fractional changes in relative humidity, not accounted for in the simple scaling, are important over land and high-latitude oceans. An extended scaling that incorporates these gradients is shown to better capture the response of P − E over land, including a smaller increase in global-mean runoff and several regions with decreases in P − E. In the zonal mean over land, the gradient terms lead to a robust drying tendency at almost all latitudes. This drying tendency is shown to relate, in part, to the polar amplification of warming in the Northern Hemisphere, and to the amplified warming over continental interiors and on the eastern side of midlatitude continents. Massachusetts Institute of Technology. Joint Program on the Science & Policy of Global Change National Science Foundation (U.S.) (Grant AGS-1148594) United States. National Aeronautics and Space Administration (ROSES Grant 09-IDS09-0049) 2016-04-19T17:08:15Z 2016-04-19T17:08:15Z 2015-10 2015-07 Article http://purl.org/eprint/type/JournalArticle 0894-8755 1520-0442 http://hdl.handle.net/1721.1/102264 Byrne, Michael P., and Paul A. O’Gorman. “The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the ‘Wet-Get-Wetter, Dry-Get-Drier’ Scaling Does Not Hold over Land.” J. Climate 28, no. 20 (October 2015): 8078–8092. © 2015 American Meteorological Society https://orcid.org/0000-0003-1748-0816 en_US http://dx.doi.org/10.1175/jcli-d-15-0369.1 Journal of Climate 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 | Byrne, Michael P. O'Gorman, Paul The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land |
| title | The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land |
| title_full | The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land |
| title_fullStr | The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land |
| title_full_unstemmed | The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land |
| title_short | The Response of Precipitation Minus Evapotranspiration to Climate Warming: Why the “Wet-Get-Wetter, Dry-Get-Drier” Scaling Does Not Hold over Land |
| title_sort | response of precipitation minus evapotranspiration to climate warming why the wet get wetter dry get drier scaling does not hold over land |
| url | http://hdl.handle.net/1721.1/102264 https://orcid.org/0000-0003-1748-0816 |
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