Collaborative Research: Effects of Eddies and Waves on the Westward Transport off Central California

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The study focuses on understanding the role of mesoscale variability and Rossby waves in the offshore propagation of kinetic energy, heat, salt and tracers to the west [referred as westward transport (WT)] in the California Current System (CCS). In-situ observations, remote-sensed observations, and numerical modeling are used to nowcast meso-scale eddy variability in the CCS off Central California and to quantify associated WT. The goal is to understand how eddies, jets and waves as well as their interactions affect WT and to determine the scales responsible for this process. Parameterization schemes for WT will also be developed in a form sufficiently simplified to be verified from sparse observations and to permit biological and climate applications. While each component of the study has its own stand-alone objectives, components are combined in a synergistic way to produce the desired nowcast product based on fusion of model results and data. Model integrations through a hierarchy of regional ROMS (UCLA) nested with a global SODA will be used as guidance in constructing reliable three-dimensional dynamics of the region of interest on mesoscale and sub-mesoscale. Satellite data (SST, altimetry and color), drifter (WOCE) and subsurface (Argo and RAFOS) float observations, and hydrographic (CTD/VMADCP) data will be used to provide a physical description of the CCS independent of the model and as a basis for independent model validation. The ROMS is validated through the feature-oriented approach using multiple metrics to find an accepted model configuration for reproduction of along- and across-shore transport in the most accurate manner. WT characteristics are revised and updated through correlation and scaling analyses applied to model results and data. The project will contribute to understanding the westward transport induced by eddies and waves in a subtropical eastern-boundary upwelling system as well as the across slope exchange on climate time scales. Eddies and waves play a major role in the transport of mass and momentum, thus affecting transport, drag, and dissipation in mesoscale flows. Due to their long lifetimes, eddies and waves redistribute the cold water upwelled near the margin that may also affect the overlying atmosphere and hence through air-sea interactions impacting both weather and climate. A significant deviation of the westward transport from conventional diffusion necessitates search for new types of parameterizations for heat and salt transport accounting for long time lag correlation effects. The proposal suggests and develops such a parameterization in context of the telegraph transport model, which may be useful for forecasting biological productivity along the Central California coast and in climate applications of oceanic models. A set of mathematical tools for image analysis, for identification and classification of coherent eddies and waves, data merging, Lagrangian analysis and model-data comparison is developed for the analysis of output fields of high-resolution oceanic models and observations. The project will involve graduate students and post-docs including women from the Naval Postgraduate School (Monterey, CA) as well as other Monterey area institutions. Research results will be converted into teaching aids for graduate and undergraduate courses at the Naval Postgraduate School and MLML. These educational materials will also be used for a graduate-level marine science textbook. Contributions will also be made to state-of-the-art surveys of marine sciences. Results should have relevance for biological productivity, fisheries, oil and gas recovery operations and navigation. Activities will include open communications and presentations to the public, policy-makers, private companies and local government officials.