GOMOS2020

Summary

Oceanweather (OWI) produced a new and comprehensive metocean hindcast database and suite of derivative products for the Gulf of Mexico (GOM) in 1999 and offered to license it to all interested parties, first as a site-specific product and, in mid-2004, as a basin-wide product. This product was referred to as GOMOS for Gulf of Mexico Oceanographic Study. GOMOS was designed to serve as a follow-on to the Joint Industry Projects (JIP) carried out at Oceanweather in the decades of the 1980s and 1990s that addressed the GOM and known as GUMSHOE, which addressed only hurricane generated metocean extremes, WINX, which addressed only
winter storm etremes, and GLOW which simulated winds and waves over a continuous period for assessment of operational statistics. The products of those JIPs had been so widely adopted that they had come to serve as de-facto metocean data for design standards. Similarly, selected GOMOS hurricane extremes have been incorporated into a publication of the American Petroleum Institute (API) that presents recommended practices for the design and operations of GOM moorings for Movable Offshore Drilling Units (MODU) (API, 2006) and another publication that provides guidance on hurricane driven metocean conditions in the GOM for use with and reference by API standards in general (API, 2007).

In 2008, the GOMOS hindcast underwent a significant upgrade which included the application of third generation (3G) wave models, 1D and 2D current and surge models, as well as an upgradedtropical planetary boundary layer (TropPBL) model which could describe more complex wind profile structures. This 2008 update, known as GOMOS08, addressed the operational, winter storm, and tropical periods up through 2008.

GOMOS2014 was released in early 2015 and was primarily an update using the models and methodologies applied in GOMOS08 to extend the hindcast through to 2014. There was, however, significant reanalysis of the tropical systems that were updated post-GOMOS08 by the Hurricane Reanalysis Project (HRP, Landsea et al., 2004 and 2008) which develops the HURDAT Atlantic Tropical Track Database. These tropical systems are mostly from the period of 1926-1950. Additionally, the storm population for the extra-tropical hindcast was expanded to contain additional storms during the 1980-2014 overlap period of the continuous hindcast. GOMOS2017 updated the continuous, tropical and extra-tropical datasets to the end of 2017. Hindcasting completed in GOMOS2014 was retained, but wind gusts are now included for all tropical and extra-tropical storms. GOMOS2017 consists of three main hindcast databases and derivative statistics. These databases address respectively the following storm populations and periods: (1) 420 tropical storms and hurricanes from the period 1900-2017; (2) 121 extra-tropical/winter storm hindcasts from the period 1950-2017; (3) a 38-year continuous hindcast of the period 1980-2017.

GOMOS2020 extends the hindcast to include continuous, tropical, and extra-tropical analysis to include the period of 2018 to 2024. Wind forcing for 2020 onward is applying the surface wind and pressure products of the ERA5 reanalysis (European Centre for Medium-Range Weather Forecasts Reanalysis 5th Generation) rather than the NCEP (National Center for Environmental Prediction) NRA (NCEP Reanalysis) products applied in previous years.

Time series, statistical analysis, extremal analysis, and wave spectra are available from each of these hindcasts separately, or as a complete set. This GOMOS2020 Project Description documents the hindcast methodologies and models applied and the extensive validation carried out to establish the accuracy of the hindcasts.

Normally, GOMOS results are licensed for a user’s particular lease block of interest. This report contains a sample so-called “GOMOS Block Specific Report” detailing the methodology and deliverables associated with a particular GOMOS2020 block specific request. The basin-wide offering of GOMOS, called GOMOS_USA (northern GOM in waters offshore the United States) and GOMOS_MEX (southern GOM in waters offshore Mexico), is also offered for GOMOS2020.

Like the proceeding JIPs, GOMOS is based on the so-called “hindcast approach”. This approach is required due to a lack of measurements over a long period of history in the area from which the design data to be estimated directly may not exist. It is necessary, therefore, to develop a historical database by application of numerical models of the surface wind, sea state, and currents to “predict” or hindcast the time and space evolution of winds, waves, and currents in all areas of interest.

GOMOS improves upon the previous Gulf of Mexico hindcasts, GOMOS and GUMSHOE, in several key areas. First, the tropical cyclone wind model and the data source and analysis methodology used to force the oceanographic response model have been greatly enhanced and applied in a complete reanalysis of every tropical system within the Gulf of Mexico in the historical period addressed. Second, all wave hindcasting was carried out with a wave model incorporating 3G physics and with higher spatial resolutions than previous efforts. The stormwave model runs also include the effect of storm driven water level changes on water depth. Third, the hydrodynamic model has been upgraded and includes tidal and wave radiation-stress inputs. Finally, the continuous hindcast addresses a much longer hindcast period than previous efforts, and in extending back to 1980 covers over four decades.

Project Highlights