State of the California Current 2010-2011: Regionally Variable Responses to a Strong (But Fleeting) La Nina

Abstract

The state of the California Current system (CCS) since spring 2010 has evolved in response to the development of cooler La Niña following the dissipation of the relatively weak and short-lived El Niño event of 2009–2010. The 2009–2010 El Niño appears to have dissipated quite rapidly in early spring 2010, yet the transition to anomalously cool conditions followed somewhat later with the onset of anomalously strong upwelling throughout the CCS in summer 2010 and the development of unusually—in some cases record— cool conditions throughout the CCS. However, following the fairly consistent emergence of cooler La Niña conditions across the CCS going into summer 2010, regional contrasts were apparent. Off southern California, the effects of both the 2009–2010 El Niño and subsequent return to La Niña conditions appear to have had modest effects on the system, and the patterns that attract interest appear to be unfolding over longer time scales (e.g., freshening of upper water column and trends in nitrate and oxygen concentrations).