Underwater gliders reveal rapid arrival of El Niño effects off California's coast

The 2009–2010 El Niño marked the first occurrence of this climate phenomenon since the initiation of sustained autonomous glider surveillance in the California Current System (CCS). Spray glider observations reveal the subsurface effects of El Niño in the CCS with spatial and temporal resolutions that could not have been obtained practically with any other observational method. Glider observations show that upper ocean waters in the CCS were unusually warm and isopycnals were abnormally deep during the El Niño event, but indicate no anomalous water masses in the region. Observed oceanic anomalies in the CCS are nearly in phase with an equatorial El Niño index and local anomalies of atmospheric forcing. These observations point toward an atmospheric teleconnection as an important mechanism for the 2009–2010 El Niño's remote effect on the midlatitude CCS.