Western Hemisphere Warm Pool
The Western Hemisphere Warm Pool (WHWP) is a region of sea surface temperatures (SST) warmer than 28.5°C that develops west of Central America in the spring, then expands to the tropical waters to the east.
The WHWP includes the tropical Atlantic Ocean (TNA) east of the Lesser Antilles, Caribbean Sea, Gulf of Mexico, and eastern north Pacific Ocean (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. 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.
The WHWP is correlated with the Tropical North Atlantic index.
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Relationship with El Niño
Study of climate records has shown a relationship between El Niño and the Western Hemisphere Warm Pool (WHWP). During normal Northern Hemisphere winter, warmth over the Amazon drives a Hadley cell with associated descending air driving a strong anticyclone north of 20°N in the subtropical North Atlantic and northeast trade winds. An El Niño weakens the Amazonian cell and the TNA warms more than usual in the spring. After about half of El Niño events, the unusually warm water along the eastern North Pacific gains further heat during the spring and the warmth spreads across the WHWP during the summer.
Climate events in area
- 1200-1100 B.P. (A.D. 800-900): Collapse of Classic Mayan civilization due to drought. Yucatán Peninsula in present Mexico. [1]
References
- Enfield, D.B, and S.-K. Lee (2005). "The Heat Balance of the Western Hemisphere Warm Pool". Journal of Climate 18: 2662-2681.
- Enfield, D.B, S.-K. Lee, and C. Wang (2005). "How are large Western Hemisphere Warm Pools formed?". Progress in Oceanography.
- 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 (October 2001). "The tropical Western Hemisphere warm pool". Geophys. Res. Lett. 28: 1635-1638.
- 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. (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.
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Categories
Climatology | Tropical meteorology