Changes in atmospheric circulation during an El Niño
| Under normal conditions there is an east-west circulation of air in the tropical Pacific which rises in the western tropical Pacific near Australia, moves at high altitude eastward, sinks in the eastern tropical Pacific near South America, and then moves westward near the surface. This pattern produces relatively high sea surface pressure and very little rain in the east (Tahiti) and relatively low sea surface pressure and much precipitation in the west (Darwin, Australia). Under El Niño conditions the strength of the westward winds near the surface decreases and the circulation of the cell breaks down. The east now has lower sea surface pressure and more rain and the west has higher sea surface pressure and drought conditions. These changes in circulation have an impact on the sea surface. |
Credit: NOAA/PMEL/TAO Project Office, Dr. Michael J. McPhaden, Director
For more info: http://www.pmel.noaa.gov/toga-tao/el-nino/nino-home.html