Figure 15. Depiction of sea-surface temperatures and the position of the thermocline in the equatorial Pacific during normal conditions and during El Niño conditions. Modified from diagrams on the web site (accessed 5/25/2001) for the Tropical Atmosphere Ocean Project, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration; see
http://www.pmel.noaa.gov/toga-tao/el-nino/nino_normal.html. La Niña is an extreme case of the normal configuration with enhanced upwelling and even cooler sea-surface temperatures in the eastern equatorial Pacific.