ACCESS NUMBER: 31076 

STUDY TITLE: Extension of the Coastal Ocean Model Calculations 

REPORT TITLE: A Circulation Model of the Gulf of Mexico and the Caribbean Sea: 

Development of the Princeton Regional Ocean Forecast (& Hindcast) System – 

PROFS, and Hindcast Experiment for 1992-1999

CONTRACT NUMBER: 1435-01-00-CT-31076 

SPONSORING OCS REGION: National 

APPLICABLE PLANNING AREA: Gulf of Mexico and the Caribbean Sea 

FISCAL YEARS OF PROJECT FUNDING: 2000, 2001 

COMPLETION DATE OF REPORT: October, 2005 

COSTS: FY 2000 $248,101; FY 2001 $95,000 

PROJECT MANAGER: L. Oey 

AFFILIATION: Princeton University 

ADDRESS: AOS Program, Sayre Hall, Princeton University, Princeton, NJ 08544 

PRINCIPAL INVESTIGATOR: L. Oey 

KEY WORDS: Gulf of Mexico; Data assimilation; Loop Current; surface currents 

BACKGROUND: The results of the study will be used by MMS to improve the OSRA 

estimates of oil spill trajectories. The ocean models have been shown to have skill in 

estimating the near surface currents. This study will extend the time series of simulated 

currents to compare to other field projects that have been conducted in the Gulf of 

Mexico, as well as the use in the OSRA calculations. Data assimilation is applied ocean 

models, so that a more accurate estimate of ocean currents may be derived for the Oil 

Spill Risk Assessment Analysis. This project implements, tests and verifies data 

assimilation methodologies in the Gulf of Mexico. 

OBJECTIVES: The objective is to provide the Minerals Management Service (MMS) 

with multi-years of hindcast currents obtained from a numerical ocean circulation model 

for the Gulf of Mexico and the adjacent U.S. southeastern shelf and slope regions. 

These currents are to be used in MMS’ OSRA computer program to derive statistics 

regarding impacts of offshore spills. To achieve the objective, a comprehensive 

circulation model for the region has been developed based on the Princeton Ocean 

Model.

DESCRIPTION: The model hindcast described in this study portrays the ocean 

circulation state in the Gulf for the period 1992-1999, using available data. The data 

included six-hourly wind field obtained from a combination of NDBC buoy data and the 
ACCESS NUMBER: 31076 

ECMWF analysis, daily river discharges from 34 U.S. rivers in the Gulf of Mexico, and 

satellite sea-surface height (SSH) anomaly and sea-surface temperature (SST). The 

satellite data were used in an assimilation scheme based on optimum interpolation. In 

addition, monthly climatological T/S data and surface fluxes were also used for 

boundary specifications. These data are deemed the most basic for a successful 

hindcast estimation of the circulation in the Gulf and adjacent seas. Other data, such as 

drifters, hydrographic measurements, and current meters were also utilized for testing 

and evaluation purposes. 

SIGNIFICANT CONCLUSIONS: It is shown that the hindcast has yielded mean 

circulation and variances that are consistent with observations. In the Gulf of Mexico, 

the model gives generally anticyclonic circulation near the surface and a cyclonic 

circulation in the deep layers, though with considerable spatial variability. Variance 

ellipses show current intensities that are in general agreement with historical data, both 

near the surface and in deep layers. The model also gives consistent results when 

evaluated in details against observations at two locations in the Gulf: DeSoto Canyon 

and Yucatan Channel. The model gives Loop Current and eddy-shedding variability, 

circulation structures and transport variability that generally agree with those observed. 

Data assimilation enables correct placements of the locations of the Loop Current and 

Loop Current eddies. It is shown that the correct placement of the Loop Current in the 

Florida Straits southwest of Florida is crucial in remotely driving currents over the west 

Florida. 

STUDY RESULTS: The model, all inputs and outputs (including all 60-day ‘restart’ files 

and standard plots) were delivered to MMS in July 2003. A Users’ Guide for the model 

was delivered to MMS in September 2003. Dr. Oey went to MMS’ Herndon (VA) offices 

in October/2003 to give a ‘training session’ on how to use the model. The model was 

demonstrated to run correctly on MMS’ workstations. 

STUDY PRODUCTS: Oey, L.-Y. and H.-C. Lee, 2002: Deep eddy energy and 

topographic Rossby waves in the Gulf of Mexico, J. Phys. Oceanogr., 32: 3499-3527 

Ezer, T., L.-Y. Oey, W. Sturges and H.-C. Lee, 2003: The variability of currents in the 

Yucatan Channel: analysis of results from a numerical ocean model, J. Geophys. 

Res. 10.1029/2002JC001509 

Fan, S.J., L.-Y. Oey, and P. Hamilton, 2004. Assimilation of drifters and satellite data in 

a circulation model of the northeastern Gulf of Mexico. Cont. Shelf Res., 24(9): 

1001-1013 

Wang, D.-P., L.-Y. Oey, T. Ezer and P. Hamilton, 2003: Nearsurface currents in DeSoto 

Canyon. J. Phys. Oceanogr., 33: 313-326 

Oey, L.-Y., H.-C. Lee and W. J. Schmitz Jr., 2003: Effects of Winds and Caribbean 

Eddies on the Frequency of Loop Current Eddy Shedding: A Numerical Model 

Study, J. Geophys. Res., 108 (C10), 3324, doi:10.1029/2002JC001698, 2003 
ACCESS NUMBER: 31076 

Oey, L.-Y. and H.-C. Zhang, 2004. A mechanism for the generation of subsurface 

cyclones and jets. Cont. Shelf Res., 24, 2109-2131 

All model inputs and outputs delivered on 15 DVD’s to MMS; 

Model code and run scripts