Transport of mass, heat, salt, and nutrients in the southern California Current System: Annual cycle and interannual variability

Net fluxes of mass, heat, salt, nutrients, oxygen, and chlorophyll into a c ontrol volume within the southern California Current System (CCS) were comp uted from data collected on 55 cruises over a 14 year period (1984-1997). T his analysis builds on an earlier work [Roemmich, 1989] by using an additio nal 39 cruises over 10 years, allowing for reliable estimates of the tempor al variability in the fluxes on seasonal and interannual timescales and a r eduction in the corresponding error budgets. A close balance was found betw een geostrophic convergence and Ekman divergence for the 14 year, seasonal, and interannual cruise subsets using three different wind products. Wind d ata taken concomitantly with the hydrographic sampling provided the best ba lance and hence the best flux estimates. The southern CCS was found to be a region with higher evaporation over precipitation and net heat gain by the ocean from the atmosphere (86 W m(-2) in the 14 year mean) in all seasons. Significant variability in both the Ekman and geostrophic transports and t he net property fluxes was found to be related to low-frequency (interpenta dal and El Nino - Southern Oscillation timescale) changes in the dominant w ind and circulation patterns in the CCS. Variability in primary productivit y, estimated from the derived nutrient fluxes, accompanied the environmenta l changes. Application of this model to the ongoing data collection will fu rther reduce the error bars on the fluxes and will allow for continued moni toring of changes in the physical and biological structure of the southern CCS.