In the California Current Ecosystem (CCE), krill represent a key link between primary production and higher trophic level species owing to their central position in the food web and tendency to form dense aggregations. However, the strongly advective circulation associated with coastal upwelling may spatiotemporally decouple the occurrence and persistence of krill hotspots from phytoplankton biomass and nutrient sources. Results from a physical-biological model provide insights into fundamental mechanisms controlling the phenology of krill hotspots in the CCE and their sensitivity to alongshore variations in primary production and ocean currents. The model solution indicates that dynamics controlling krill hotspot formation, intensity and persistence are strongly heterogeneous and must be understood in the context of local alongshore variations in coastal upwelling, modulated by regional circulation patterns. Furthermore, the model suggests that regions promoting krill aggregations in the CCE coincide with increased observed abundances of key marine mammal and seabird species.

This dataset is a subset of a coupled physical-biogeochemcial model for the central California Current upwelling system. The physical model is an implementation of the Regional Ocean Modelling System (ROMS; www.myroms.org) coupled to NEMUCSC, a customized version of the North Pacific Ecosystem Model for Understanding Regional Oceanography (NEMURO). The NEMUCSC biogeochemical model includes three limiting macro-nutrients, two phytoplankton functional groups, three zooplankton size-classes, and three detritus pools. To better represent the combined effects of regional circulation patterns and local upwelling intensity on alongshore biophysical properties, the model downscales a data-assimilative physical reanalysis at 1/10° (~10 km) resolution for the broader California Current system to a higher 1/30° (~3 km) resolution domain for the central California Current region. A subset of variables were extracted from the full daily model output at various depths and subsequently averaged monthly for 1990-2010 using Ferret V7.1 (http://ferret.pmel.noaa.gov/Ferret). The dataset is in NetCDF4 format (CF-1.4 compliant) with metadata describing each variable name and associated units on the native ROMS grid.

All necessary information to use this dataset is contained in the metadata (variable name, units, missing value flag, etc.).