The Western Hemisphere Warm Pool (WHWP) is a region of

sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mas ...

s (SST) warmer than 28.5 °C that develops west of

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

in the spring, then expands to the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

waters to the east. The WHWP includes the tropical

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

(TNA) east of the

Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc bet ...

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

, and eastern north

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

(ENP). A WHWP heating cycle begins with warmth in the eastern North Pacific in the spring. A dipole pattern off Central America appears due to surges of cooler, drier air through the gap at the

Isthmus of Tehuantepec The Isthmus of Tehuantepec () is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. Before the opening of the Panama Canal, it was a major overland transport route known simply as the T ...

. During spring, the warm pools grow and merge. Their warmth and moisture feed the Mexican monsoon. By summer, the warmth spreads across the Gulf of Mexico and Caribbean areas.

Relationship with Atlantic Hurricanes

Recent studies have shown that the Atlantic portion of the WHWP (AWP) is significantly correlated with Atlantic hurricane activity. A large (or small) AWP reduces (or increases) the tropospheric vertical wind shear in the main development region for Atlantic hurricanes and increases (or decreases) the moist static instability of the troposphere, both of which favor (or don't favor) the intensification of tropical storms into major hurricanes.

Relationship with El Niño

A study of climate records has shown a relationship between

El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...

and the Western Hemisphere Warm Pool (WHWP). During a normal Northern Hemisphere winter, diabatic heating over the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

drives a

Hadley cell The Hadley cell, named after George Hadley, is a global-scale tropical atmospheric circulation that features air rising near the equator, flowing poleward at a height of 10 to 15 kilometers above the earth's surface, descending in the subtropics ...

with descending air over an anticyclone north of 20°N in the subtropical North Atlantic and associated northeast

trade wind The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisph ...

s between Africa and the Caribbean. An El Niño weakens the Amazonian cell, the anticyclone and the easterly tradewinds, causing the tropical North Atlantic to warm more than usual in the spring. About half of El Niño events persist sufficiently into the spring months for the warm pool to become unusually large by summer.

Climate events in area

* 800-900: Collapse of Classical Maya civilization due to drought.

Yucatán Peninsula The Yucatán Peninsula (, also , ; es, Península de Yucatán ) is a large peninsula in southeastern Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north ...

in present-day

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. * August 29, 2005: Hurricane Katrina.

New Orleans New Orleans ( , ,New Orleans

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

and

Gulf Coast The Gulf Coast of the United States, also known as the Gulf South, is the coast, coastline along the Southern United States where they meet the Gulf of Mexico. The list of U.S. states and territories by coastline, coastal states that have a shor ...

region.National Hurricane Center
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References

* Wang, C., S.-K. Lee and D. B. Enfield, 2008: Atlantic warm pool acting as a link between Atlantic multidecadal oscillation and Atlantic tropical cyclone activity. Geochem. Geophys. Geosyst., 9, Q05V03, . (In the special issue of "Interactions between climate and tropical cyclones on all timescales") * Wang, C., S.-K. Lee and D.B. Enfield, 2008: Climate response to anomalously large and small Atlantic warm pools during the summer. Journal of Climate, Vol. 21, No. 11, 2437–2450. * Wang, C., S.-K. Lee and D.B. Enfield, 2007: Impact of the Atlantic warm pool on the summer climate of the western hemisphere . Journal of Climate, Vol. 20, No. 20, 5021-5040. * Lee, S.-K., D.B. Enfield and C. Wang, 2007: What drives seasonal onset and decay of the Western Hemisphere Warm Pool?. Journal of Climate, Vol. 20, No. 10, 2133-2146. * Wang, C. and S.-K. Lee, 2007: Atlantic warm pool, Caribbean low-level jet, and their potential impact on Atlantic hurricanes. Geophysical Research Letter, Vol. 34, No. L02703, . * Wang, C., D.B. Enfield, S.-K. Lee and C.W. Landsea, 2006: Influences of Atlantic Warm Pool on western hemisphere summer rainfall and Atlantic Hurricanes. Journal of Climate, Vol. 19, No. 12, 3011-3028. * Enfield, D.B. and S.-K. Lee, 2005: The Heat Balance of the Western Hemisphere Warm Pool. Journal of Climate, Vol. 18, No. 14, 2662-2681. * Enfield, D.B., S.-K. Lee, and C. Wang, 2005: How are large Western Hemisphere Warm Pools formed?. Progress in Oceanography. * Wang, C., 2005: ENSO, Atlantic climate variability, and the Walker and Hadley circulations. In The Hadley Circulation: Present, Past, and Future, H. F. Diaz and R. S. Bradley, Eds., Kluwer Academic Publisher: 173-202. * Lee, S.-K., D.B. Enfield, and C. Wang, 2003: Ocean general circulation model sensitivity experiments on the annual cycle of Western Hemisphere Warm Pool. Journal of Geophysical Research 110: C09004, doi=10.1029/2004JC002640. . * Wang, C. and D.B. Enfield, 2003: A Further Study of the Tropical Western Hemisphere Warm Pool. Journal of Climate 16 (16): 1476-1493. * Wang, C. and D.B. Enfield, 2001: The tropical Western Hemisphere warm pool. Geophys. Res. Lett. 28: 1635-1638. {{doi, 10.1029/2000GL011763.

External links

Central American coral records
Regional climate effects Tropical meteorology Natural history of the Americas Natural history of Central America Natural history of the Caribbean