Walker circulation

Walker circulation

The Walker circulation (or Walker cell) is an idealized air flow which forms, on average, zonal atmospheric circulation of air at the equator and its proximity. It is caused by differences in heat distribution between ocean and land. It was discovered by Gilbert Walker. Since then several meridional cells have been characterized in the tropical atmosphere.

Oceanic effects

The Walker cell is indirectly related to upwelling off the coasts of Peru and Ecuador. This brings nutrient-rich cold water to the surface, increasing fishing stocks.

El Niño

The Walker circulation is caused by the pressure gradient force that results from a high pressure system over the eastern Pacific ocean, and a low pressure system over Indonesia. When the Walker circulation weakens or reverses, an El Niño results, causing the ocean surface to be warmer than average, as upwelling of cold water occurs less or not at all. An especially strong Walker circulation causes a La Niña, resulting in cooler ocean temperatures due to increased upwelling.

A scientific study published in May 2006 in the journal Nature indicates that the Walker circulation has been slowing since the mid-19th Century. The authors argue that global warming is a likely causative factor in the weakening of the wind pattern. [http://www.gfdl.noaa.gov/research/climate/highlights/index.html#walker]

References

* Climate research summary - [http://www.gfdl.noaa.gov/research/climate/highlights/index.html#walker Walker Circulation: a tropical atmospheric circulation slow-down] Text and graphics from NOAA / Geophysical Fluid Dynamics Laboratory
* [http://www.eurekalert.org/pub_releases/2006-05/ncfa-sit050106.php Slowdown in tropical Pacific flow pinned on climate change ] - press release from University Corporation for Atmospheric Research.
* [http://www.nature.com/nature/journal/v441/n7089/abs/nature04744.html Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing ] 4 May 2006 in Nature (journal).
* [http://www.breitbart.com/news/2006/05/03/D8HCH8VO2.html Associated Press news story, 3 May 2006: "Global Warming Cited in Wind Shift"]

ee also

*Atmospheric circulation
*Earth's atmosphere


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Circulation Atmosphérique — Vue idéalisée des trois cellules ou zones de circulation atmosphérique La circulation atmosphérique est le mouvement à l échelle planétaire de la couche d air entourant la Terre qui redistribue la chaleur provenant du Soleil en conjonction avec… …   Wikipédia en Français

  • Circulation atmospherique — Circulation atmosphérique Vue idéalisée des trois cellules ou zones de circulation atmosphérique La circulation atmosphérique est le mouvement à l échelle planétaire de la couche d air entourant la Terre qui redistribue la chaleur provenant du… …   Wikipédia en Français

  • Circulation méridionale — Circulation atmosphérique Vue idéalisée des trois cellules ou zones de circulation atmosphérique La circulation atmosphérique est le mouvement à l échelle planétaire de la couche d air entourant la Terre qui redistribue la chaleur provenant du… …   Wikipédia en Français

  • Circulation zonale — Circulation atmosphérique Vue idéalisée des trois cellules ou zones de circulation atmosphérique La circulation atmosphérique est le mouvement à l échelle planétaire de la couche d air entourant la Terre qui redistribue la chaleur provenant du… …   Wikipédia en Français

  • Circulation atmosphérique — Vue idéalisée des trois cellules ou zones de circulation atmosphérique La circulation atmosphérique est le mouvement à l échelle planétaire de la couche d air entourant la Terre qui redistribue la chaleur provenant du Soleil en conjonction avec… …   Wikipédia en Français

  • Walker (tool) — A walker or walking frame is a tool for disabled or elderly people who need additional support to maintain balance or stability while walking. The British English common equivalent term for a walker is Zimmer Frame from Zimmer Holdings, a major… …   Wikipedia

  • Walker, David — born Sept. 28, 1785, Wilmington, N.C., U.S. died June 28, 1830, Boston, Mass. U.S. abolitionist. The son of a slave father and a free mother, he was educated and traveled widely before settling in Boston, where he became an abolitionist lecturer… …   Universalium

  • Atmospheric circulation — is the large scale movement of air, and the means (together with the smaller ocean circulation) by which heat is distributed on the surface of the Earth. The large scale structure of the atmospheric circulation varies from year to year, but the… …   Wikipedia

  • General circulation — vereinfachtes Schema der globalen Zirkulation Die planetarische Zirkulation, oder auch allgemeine, planetare oder globale Zirkulation (englisch: general circulation, global circulation), ist eine Sammelbezeichnung für atmosphärische… …   Deutsch Wikipedia

  • Karen Walker (Will & Grace) — Infobox character colour = gray name = Karen Walker size = 200px caption = Megan Mullally as Karen Walker first = Pilot; Love and Marriage last = Finale cause = Series End nickname = Kare; Miss Karen; Kare Bear, Kiki alias = Anastasia… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”