| 词条 | Tehuantepecer |
| 释义 |
Tehuantepecer, or Tehuano wind, is a violent mountain-gap wind traveling through Chivela Pass, most common between October and February, with a summer minimum in July. It originates from eastern Mexico and the Bay of Campeche as a post-frontal northerly wind, accelerated southward by cold air damming, which crosses the isthmus and blows through the gap between the Mexican and Guatemalan mountains. The term dates back to at least 1929.[1] This wind can reach gale, storm, and hurricane force. The leading edge of its outflow (or cold front) may form rope cloud over the Gulf of Tehuantepec. These winds can be observed on satellite pictures such as scatterometer wind measurements, they influence waves which then propagate as swell and are sometimes observed {{convert|1600|km|mi|abbr=on|-2}} away (such as in the Galapagos Islands). These strong winds bring cooler sub-surface waters to the surface of the tropical eastern Pacific ocean and may last from a few hours to 6 days. Climatology{{See also|Cold front|El Niño–Southern Oscillation}}The synoptic condition is associated with high-pressure system forming in Sierra Madre in the wake of an advancing cold front. Tehuantepecers primarily occur during the cold season months for the region in the wake of cold fronts, between October and February, with a summer minimum in July caused by the westward extension of the Azores-Bermuda high pressure system. Wind magnitude is greater during El Niño years than during La Niña years, due to the more frequent cold frontal incursions during El Niño winters.[2] Tehuantepec winds reach {{convert|20|kn|km/h|-1}} to {{convert|45|kn|km/h|-1}}, and on rare occasions {{convert|100|kn|km/h|-1}}. The wind’s direction is from the north to north-northeast.[3] It leads to a localized acceleration of the trade winds in the region, and can enhance thunderstorm activity when it interacts with the Intertropical Convergence Zone.[3] The effects can last from a few hours to six days.[5] As seen by weather satellitesIts leading edge shows up as a rope cloud within the visible and infrared channels of weather satellite images, and since it lies at the leading edge of a density (temperature and dew point) discontinuity, its leading edge by definition it is a cold front, though it has also been described as a squall line, with embedded rain squalls sometimes seen.[5] Within polar orbiting imagery, a corridor of strong low-level winds show up this feature within scatterometer data retrievals, with its leading edge at the south to southwest edge of the wind surge. Ocean impactTehuantepecers can be felt up to {{convert|160|km|mi|-1}} out to sea in the tropical eastern Pacific ocean.[4] Sustained winds at sea have been recorded as high as {{convert|49.9|m/s|kn|abbr=on}}, with gusts as high as {{convert|60.2|m/s|kn|abbr=on}}, with a wind event in February 1974 which sandblasted the ship which took the observation.[5] These winds cause waves which then propagate as swell and are sometimes observed {{convert|1600|km|mi|-2}} away (e.g., in the Galapagos Islands). Its effects can appear similar to a tropical cyclone, though the sky is usually clear. The surface wind can also change local ocean currents during an event.[6] These strong winds upwell sub-surface waters, cooling the tropical eastern Pacific ocean by as much as 14 °F (9 °C),[7] and may last 4–7 days. References1. ^{{cite journal|author=Willis E. Hurd|title=Northers of the Gulf of Tehuantepec|journal=Monthly Weather Review|volume=57|number=5|date=May 1929|pages=192–194|publisher=American Meteorological Society|doi=10.1175/1520-0493(1929)57<192:notgot>2.0.co;2|bibcode = 1929MWRv...57..192H }} 2. ^{{cite journal|author1=Rosario Romero-Centeno |author2=Jorge Zavala-Hidalgo |author3=Artemio Gallegos |author4=James J. O’Brien |last-author-amp=yes |title=Isthmus of Tehuantepec wind climatology and ENSO signal|journal=Journal of Climate|volume=16|number=15|pages=2628–2639|date=August 2003|doi=10.1175/1520-0442(2003)016<2628:iotwca>2.0.co;2|bibcode = 2003JCli...16.2628R }} 3. ^{{cite web|url=http://www.nrlmry.navy.mil/sat_training/world_wind_regimes/tehantepecer/index.html|title=World Wind Regimes - Central America Gap Wind Tutorial|publisher=United States Naval Research Laboratory Monterey, Marine Meteorology Division|author=Bob Fett|date=2002-12-09|accessdate=2013-05-16}} 4. ^1 {{cite web|url=http://glossary.ametsoc.org/wiki/Tehuantepecer|work=Glossary of Meteorology|title=Tehuantepecer|date=2012-01-26|accessdate=2013-05-16|author=American Meteorological Society}} 5. ^{{cite journal|journal=Monthly Weather Review|volume=125|date=January 1997|pages=6–7|title=The 1993 Superstorm Cold Surge: Frontal Structure, Gap Flow, and Tropical Impact|author1=David M. Schultz |author2=W. Edward Bracken |author3=Lance F. Bosart |author4=Gregory J. Hakim |author5=Mary A. Bedrick |author6=Michael J. Dickinson |author7=Kevin R. Tyle |last-author-amp=yes |doi=10.1175/1520-0493(1997)125<0005:TSCSFS>2.0.CO;2|bibcode=1997MWRv..125....5S}} 6. ^1 2 {{cite journal|journal=Mariners Weather Log|author=Paul A. Arnerich|title=Tehuantepecer Winds of the West Coast of Mexico|pages=63–67|volume=15|number=2|publisher=National Oceanic and Atmospheric Administration}} 7. ^{{cite journal|journal=Monthly Weather Review|author=Willis E. Hurd|publisher=American Meteorological Society|date=November 1939|page=432|volume=67|number=11|title=Tehuantepecer of November 24, 1939|doi=10.1175/1520-0493(1939)67<432:ton>2.0.co;2|bibcode = 1939MWRv...67..432H }} Other reading
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