La Nina in progress : Image of the Day

La Nina in progress : Image of the Day

Continuing a trend that began earlier in the year, La Niña conditions strengthened through the summer of 2010, evidenced by a streak of cool water across the equatorial Pacific Ocean. Acquired by the Ocean Surface Topography Mission/Jason-2 satellite, this map shows a 10-day average of sea-surface height centered on September 6, 2010. Because water expands with rising temperatures, satellites can use sea-surface height as a proxy for temperature. Areas where the water surface is higher (and therefore warmer) than average are shades of red-brown, and areas where the water surface is lower (cooler) than average are blue. Normal conditions appear in white.