From Nasa’s Earth Observatory, click here to see and read how the 2015 El Nino is evolving into a stronger event than expected.The maps of sea surface height anomalies on this page provide NASA’s view of Pacific Ocean conditions since April 2015. The sea surface height anomalies are a measure of the difference between the long-term monthly mean sea surface height from the single monthly mean in a given year of interest. The sea surface height is another way to visually observe thermal warming or cooling in the surface ocean, since it will increase with warming due to thermal expansion. Thermal expansion of water detected using satellite-based sea surface height data provides a unique way of tracking the changes in ocean heat content on seasonal and longer timescales.
Image: Data from ocean-observing satellites and other ocean sensors indicate that El Niño conditions appear to be developing in the equatorial Pacific Ocean. Conditions in May 2014 bear some similarities to those of May 1997, a year that brought one of the most potent El Niño events of the 20th century. Data courtesy NASA JPL Ocean Surface Topography Team and maps by Marit Jentoft-Nilsen and Robert Simmon.