The studies are designed to elucidate mechanisms that determine how physical features influence ecosystem processes. The investigators will develop nested models that encompass phenomena across the entire North Pacific basin -- e.g., ENSO and regime shift/PDO-linked features -- and incorporate variability over interannual to decadal time scales. They will direct special attention to zooplankton, at both the individual population level (e.g., euphausiids), and at the aggregated community level and employ advanced data assimilation (e.g., of the mesoscale surveys) to produce optimal merged data/model products for use by the GLOBEC NEP synthesis effort. The coupled physical-ecosystem model products will include dynamically consistent, data-assimilative hindcasts for the region and time of the CCS field experiments and multi-decadal, basin-scale, nested calculations (1970-present). With this research, the investigators seek to (i) quantify how physical features in the California Current System and variability related to climate change impact zooplankton biomass, production, distribution, and the retention and loss of zooplankton from coastal regions and (ii) compare the impacts of climate variability and change (such as El Nino-La Nina cycles and regime shifts) on marine animal populations (euphausiids) in the CCS and CGOA. Both of these respond directly to stated goals of the GLOBEC NEP synthesis program. In addition, this project will afford the opportunity for multiple Ph.D. scientists and undergraduate students, working either directly with the PIs or by attendance at the proposed workshops, to participate in GLOBEC synthesis.