New remote sensing data from NASA’s Jason-2 satellite show near-normal sea-surface height conditions across the equatorial Pacific Ocean. This neutral, or “La Nada” event, has stubbornly persisted for 16 months, since spring 2012.
Jason-2 is a joint effort between NASA, the National Oceanic and Atmospheric Administration (NOAA), the French Space Agency Centre National d’Etudes Spatiales (CNES) and the European Organization for the Exploitation of Meteorological Satellited (EUMETSAT).
The National Weather Service’s Climate Prediction Center said models suggest this pattern will continue through the spring of 2014.
“Without an El Niņo or La Niņa signal present, other, less predictable, climatic factors will govern fall, winter and spring weather conditions,” climatologist Bill Patzert of NASA’s Jet Propulsion Laboratory, in Pasadena, California, said.
“Long-range forecasts are most successful during El Niņo and La Niņa episodes. The ‘in between’ ocean state, La nada, is the dominant condition, and is frustrating for long-range forecasters. It’s like driving without a decent road map- it makes forecasting difficult.
For the past several decades, about half of all years have experienced La Nada conditions, compared to about 20 percent El Niņo and 30 percent for La Niņa. Patzert noted that some of the wettest and driest winters occur during La Nada periods.
“Neutral infers something benign, but in fact if you look at these La Nada years when neither El Niņo nor La Niņa are present, they can be the most volatile and punishing,”Patzert said. “As an example, the continuing, deepening drought in the American West is far from ‘neutral’”.
Above-normal height variations along the equatorial Pacific indicate El Niņo conditions, while below-normal height variations indicate La Niņa conditions. The temperature of the upper ocean can have a significant influence on weather patterns and climate.
NASA scientists will continue to monitor this persistent La Nada event to see what the Pacific Ocean has in store next for the world’s climate.
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