Interannual variability of new production in the southern region of the California Current

New primary production (Pnew) (g C m−2 d−1) interannual variability for offshore and inshore regions of the southern California Current from September 1969 to September 2002, using CalCOFI and IMECOCAL data (CalCOFI Lines 90, 107, and 120), was estimated. Total primary production (PT) and the f-ratio were estimated using empirical algorithms based on nitrate and temperature ship data. Monthly new production (Pnew=PT·f-ratio) values were calculated from these empirical data. Time series of Pnew anomalies (APnew, g C m−2 d−1) were generated for each line. The period from 1977 to 1998 was characterized by frequent negative APnew values (∼0.10 g C m−2 d−1), while the years 1999–2002 had relatively high APnew positive values (up to 0.14 g C m−2 d−1). The sequence of negative and positive APnew values followed not only that of El Niño–La Niña events, but also the interdecadal regime shifts. A cold regime was present in our study area during the 1970s, up to 1976, after which there was a change to positive anomalies up to 1998. During the no-ENSO years, APnew was approximately 20% higher than those of ENSO years.