Topic 4: Assesment of Global Ocean Data Assimilation Experiment (GODAE) Boundary Conditions for Coastal Ocean Predictions

Assessing the Impact of GODAE Boundary Conditions on the Estimate and Prediction of the Monterey Bay and California Central Coast Circulation

Lead PI: Dr. Christopher Edwards, University of California, Santa Cruz

The objective of this proposal is to use the recently developed ROMS 4D variational data assimilation, ensemble prediction, and generalized stability analysis toolkits to explore the influence that open boundary conditions from Global Ocean Data Assimilation Experiment (GODAE) products and satellite-derived data have on the observability and predictability of the Monterey Bay and greater California central coast circulation. Although the coastal circulation is in part driven by strong local forcing when present, the generally narrow continental shelf and open coastline of this region also leave it exposed to the energetic mesoscale circulation of the California Current System and more generally to the stratification and transports of the eastern Pacific ocean.

The Center for Integrated Marine Technologies (CIMT) is a NOAA funded program, carrying out a wide range of observations as well as modeling of the physical and biological properties of Monterey Bay. It is a major contributor to the Central and Northern California Coastal Ocean Observing System (CeNCOOS). These observations, combined with our current capability to model this region and the new ROMS toolkits provide the foundation of this proposal.

We have identified multiple approaches to investigate quantitatively the relative influence of GODAE-derived boundary conditions, assimilated satellite data, and surface fluxes on the regional circulation. Several metrics relevant to our region and consistent with the available, in situ observing system are described. Specifically, we propose to:

use the adjoint ROMS and error estimates from the GODAE and satellite products to explore the sensitivity of metrics that characterize the physical circulation of Monterey Bay and the central coast to errors and uncertainties in the open boundary conditions, initial conditions and surface forcings;
analyze the variance of efficiently perturbed ensembles of Monterey Bay hindcasts and forecasts to further explore the sensitivity of predictions to uncertainties in GODAE open boundary conditions;
assess the impact of GODAE boundary conditions on regional weather prediction by applying our improved SST estimates as a lower boundary condition to a regional atmospheric model;
compute and analyze representer functions for different observation types and locations to identify those of maximum value for the observation system.

NOAA-PFEL will provide the satellite data as well as develop and apply new feature tracking metrics both to observations and our model output. The ECCO-GODAE consortium will provide estimates of transport and vertical structure of the open ocean, and multiple approaches to blend the large-scale information and the regional ocean model will be compared. Feedback to the GODAE partners is explicit. The first two years of the analysis will focus on late 2002 through 2003, for which both observations and mature boundary conditions exist today. During year 3 of the proposal, we will extend our sensitivity studies to the present, when additional data sets, such as expanded surface current estimates by long-range HF radar, are expected.

Number of Years: 3

Requested Funds: $1,192,216

Partners:

University of Colorado
Massachusetts Institute of Technology
Naval Research Laboratory
Pacific Fisheries and Environmental Laboratory

HYCOM Costal Ocean Hindcasts and Predictions: Impact of Nesting in HYCOM GODAE Assimilative Hindcasts

Lead PI: Dr. George Halliwell, University of Miami

The primary goal is to evaluate and potentially improve the HYbrid Coordinate Ocean Model (HYCOM) GODAE ocean data assimilation product for providing initial and boundary conditions to nested HYCOM coastal ocean hindcasts (performed with and without satellite data assimilation) and forecasts. Specific objectives include (1) determining the impact of the HYCOM GODAE product on the capability of nested models to hindcast and predict the coastal ocean environment; (2) determining the impact of assimilating satellite observations with vertical projections provided by the Navy Coupled Ocean Data Assimilation (NCODA) system into nested coastal models; (3) evaluating the coastal hindcasts and predictions with observations that include existing elements of the Coastal Ocean Observing System; (4) identifying the most useful observations that should be maintained as part of a coastal observation network; and (5) providing feedback for improving the HYCOM GODAE product. The overall regional focus will encompass the coastal Gulf of Mexico and the Florida Straits with emphasis on three regions: the South Florida Coastal Region (SFCR), including the Florida Straits, the Florida Keys and Atlantic Keys shelf, Florida Bay, and the adjacent southwest Florida shelf; the entire West Florida Shelf (WFS); and the Northern Gulf Coastal Region (NGCR). These subregions provide a broad range of shelf geometries, river and estuarine runoff, atmospheric forcing, and both weak and strong offshore forcing for evaluating the impact of initial/boundary conditions provided by the HYCOM GODAE data assimilative product. The WFS effort, presently focused about a nested ROMS model, will compare ROMS to nested HYCOM runs to determine to what extent sensitivity to initial and boundary conditions is model dependent. To achieve these goals, we have assembled a partnership consisting of (1) RSMAS, University of Miami, with G. Halliwell (lead investigator), E. Chassignet, L. K. Shay, and V. Kourafalou; (2) the University of South Florida with R. Weisberg [assisted by A. Barth, A. Alvera, and R. He (WHOI)]; (3) The Naval Research Laboratory (NRL), Stennis Space Center, with H. Hurlburt, P. Hogan, J. Cummings, and A. Wallcraft; and (4) Planning Systems, Inc. (PSI) with O.-M. Smedstad. The proposed project builds upon the existing HYCOM NOPP project supporting the development of the GODAE global ocean data assimilation system.

Number of Years: 3

Requested Funds: $1,419,434

Partners:

University of Southern Florida
Planning Systems, INC
Naval Research Laboratory, Stennis Space Center

Boundary conditions, data assimilation, and predictability in coastal ocean models

Lead PI: Dr. Roger Samelson, Oregon State University

Goals and Objectives Research is proposed to determine the impact of open ocean boundary conditions from GODAE Pacific Ocean models on numerical model simulations of Oregon coastal ocean circulation. The proposed research will address the direct impact of boundary conditions from the 1/12° Pacific HYCOM model and two intermediate-scale models on the coastal model. The intermediate-scale models have high-resolution atmospheric forcing and boundary conditions from the basin-scale GODAE model. The impact on the coastal ocean simulations of assimilating satellite remote sensing observations, including sea-surface heights and temperatures, and of using scatterometer wind stress fields will also be addressed. Validation of the simulated coastal ocean circulation will be provided by existing elements of the Oregon coastal ocean observing system, including short-range and long-range coastal HF radar arrays, and by extensive in-situ data sets from major observational programs during 2000-2003. The impact of the boundary conditions will be assessed quantitatively through data assimilation, using a variational representer-based generalized inverse method. The closely related issues of uncertainty and predictability in coastal ocean circulation models will be addressed using a variety of empirical and theoretical methods to study disturbance growth mechanisms and to develop uncertainty budgets for these models. Issues analogous to those addressed here for the coastal ocean arise generally in limited-area modeling of the mesoscale atmosphere, and the proposed collaboration consequently includes expertise in atmospheric modeling, in order to stimulate and take maximal advantage of progress on shared challenges. The proposed collaboration includes a large-scale GODAE modeler, which will ensure the relevance of the project to GODAE goals and facilitate the transfer of research results and their implications to the developers of the GODAE system.

Number of Years: 3

Requested Funds: $1,209,987

Partners: