Chapter 14 - Equatorial Processes
14.6 Important Concepts
- Equatorial processes are important because heat released by rain in the
equatorial region drives an important part of the atmospheric circulation.
- Equatorial currents redistribute heat. The interannual variability of currents
and temperatures in the equatorial Pacific modulates the oceanic
forcing of the atmosphere.
- Changes in equatorial dynamics cause changes in atmospheric circulation.
- El Niño causes the biggest changes in equatorial dynamics. During El
Niño, trade-winds weaken in the western Pacific, the thermocline becomes
less deep in the west. This drives a Kelvin wave eastward along the equator,
which deepens the thermocline in the eastern Pacific. The warm pool
in the west moves eastward toward the central Pacific, and the intense
tropical rain areas move with the warm pool.
- As a result of El Niño, drought occurs in the Indonesian area and
northern Australia, and floods occur in western, tropical South America.
in the atmospheric circulation influence more distant areas through teleconnections.
- Forecasts of El Niño are made using coupled ocean-atmospheric numerical
models. Forecasts appear to have useful accuracy for 3–6 months in
advance, mostly after the onset of El Niño.