High resolution modeling and data assimilation in the Monterey Bay area

Abstract

A high resolution, data assimilating ocean model of the Monterey Bay area (ICON model) is under development within the framework of the project “An Innovative Coastal-Ocean Observing Network” (ICON) sponsored by the National Oceanographic Partnership Program. The main objective of the ICON model development is demonstration of the capability of a high resolution model to track the major mesoscale ocean features in the Monterey Bay area when constrained by the measurements and nested within a regional larger-scale model. This paper focuses on the development of the major ICON model components, including grid generation and open boundary conditions, coupling with a larger scale, Pacific West Coast (PWC) model, atmospheric forcing etc. Impact of these components on the Model's predictive skills in reproducing major hydrographic conditions in the Monterey Bay area are analyzed. Comparisons between observations and the ICON model predictions with and without coupling to the PWC model, show that coupling with the regional model improves significantly both the correlation between the ICON model and observed ADCP currents, and the ICON model's skill in predicting the location and intensity of observed upwelling events. Analysis of the ICON model mixed layer depth predictions show that the ICON model tends to develop a thicker than observed mixed layer during the summer time, and while assimilation of sea surface temperature data is enough for development of observed thin mixed layer in the regional larger-scale model, the fine-resolution ICON model needs variable heat fluxes as surface boundary conditions for the accurate prediction of the vertical thermal structure. The paper targets researchers involved in high-resolution numerical modeling of coastal areas in which the dynamics are determined by the complex geometry of a coastline, variable bathymetry and by the influence of complex water masses from a complicated hydrographic system (such as the California Current system).