West Coast ROMS
UCSC California Current Ocean Modeling and Data Assimilation
This page displays three views of the California Current System using the Regional Ocean Modeling System (ROMS), implemented by the UC Santa Cruz Ocean Modeling Group. These figures are updated each day to display modeled ocean conditions for approximately one day in the future (see dates on each figure). Sea surface height (i.e. sea level), sea surface temperature with surface currents and sea surface salinity with surface currents are shown in the figures below. Click each figure for a larger view.
Find older figures beginning January 1st, 2011 as well as further details on the project at the UCSC Near-Real Time CCS Modeling website.
Download NetCDF files of model data from the entire water column beginning January 1st, 2011.
The California Current System (CCS). The CCS extends approximately 1000 km off the U.S. west coast from Washington State to Baja California peninsula in Mexico. The CCS is defined by the year-round broadly southward surface motion, a narrow subsurface northward flow (the California Undercurrent) often found at 100-300 meters along the continental slope, and an occasional nearshore northward surface current often strongest in fall.
Modeled Conditions. The figures above are snapshots of modeled surface ocean conditions for the CCS. The figures show (1) sea surface height (SSH), which varies about 1/2 meter within the CCS; (2) sea surface temperature (SST), which usually shows a strong gradient between the warm subtropical waters to the southwest and cold subpolar waters to the north or cold upwelled waters along the coast; and (3) sea surface salinity (SSS), which has a typical CCS value of about 33 practical salinity units (PSU), varying slightly due to more precipitation in the north and more ocean evaporation in the south. Superposed on the SST and SSS figures are surface velocity vectors (black arrows) showing the direction and relative speed of the ocean currents.
Model Details. The ROMS model used for this project has a resolution of roughly 10 km (1/10 degree). Although the figures above show only the surface, the model includes depths from the surface to the ocean bottom (as deep as 5000 meters) in 42 different depth bins. Data from all these levels are available as NetCDF files. The model uses atmospheric fields produced by the Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS) which is run in near-real-time by the Naval Research Laboratory. For the figures above, information is also included from the 2005 World Ocean Atlas. The model does not include tides or freshwater forcing by rivers.
Data Assimilation. The figures shown on this page do not include this component, but archived figures with data assimilation can be found on the UCSC CCS Modeling website. To increase the accuracy of the ROMS model, 'Posterior' figures are created by assimilating various data sources every Monday evening for a ocean state-estimate of the previous 7 days. The data assimilation approach used by the UCSC Ocean Modeling Group applies the 4-D Variational Assimilation (IS4DVAR) method. The fourth dimension refers to adjustement of the model based on conditions over time. The following datasets are assimilated each week: AVISO Sea Level Anomalies, OSTIA Sea Surface Temperature, subtidally averaged tide-guage data, and subsurface temperature and salinity from a glider run along CalCOFI line 67 by the Monterey Bay Aquarium Research Institute (MBARI). Currents data are not presently assimilated. Current vectors are model predictions based on fundamental principles of fluid dynamics, and directly related to other (assimilated) fields such as sea surface height.
Future of this model and webpage. UCSC plans to eventually display figures up to today's date. They also will have historical models of the CCS since the year 2000.
UCSC Contributors: Christopher A. Edwards, Andrew M. Moore, Milena Veneziani, Gregoire Broquet, Hernan Arango (Rutgers University) and Patrick Drake.
Webpage created: September 2011