SS: Metocean: Validation of HYCOM current profiles using MMS NTL observations

Abstract

Abstract The HYCOM (HYbrid Coordinate Ocean Model) consortium, sponsored by the National Ocean Partnership Program (NOPP), provides near real time global estimates of daily mean current data back to November 2003. In April 2005, the US Minerals Management Service (MMS) issued a Notice to Lessees and Operators (NTL) regarding the reporting of ocean current data in the deep water of Gulf of Mexico. An extensive body of NTL current data has since been collected by the offshore oil and gas industry and made available via the National Data Buoy Center (NDBC) web site. This provides an extremely valuable source of observational data for current model validation at deepwater drilling locations in the Gulf of Mexico. Careful validation of the HYCOM model is required to ensure critical features of the current regime are adequately represented and to assess model skill. The paper describes the methodology and results of a HYCOM current model validation exercise using the MMS NTL observations in the Gulf of Mexico. The suitability of the model for the offshore industry in Gulf of Mexico is discussed. Introduction As the offshore industry is moving to ever-deeper waters, assessment of the ocean current is required. The knowledge of the ocean currents through depth is essential to riser design and control, operation of Dynamically Positioned Vessels, and other elements of engineering design and operation of deepwater oil and gas facilities. The Hybrid Coordinate Ocean Model (HYCOM) consortium is a multi-institutional effort funded by the National Ocean Partnership Program (NOPP), as part of the U. S. Global Ocean Data Assimilation Experiment (GODAE), to develop and evaluate a data-assimilative hybrid isopycnal-sigma-pressure (generalized) coordinate ocean model (called HYbrid Coordinate Ocean Model or HYCOM). The horizontal dimensions of the global grid are 4500 × 3298 grid points resulting in ~7 km spacing on average. There are up to 32 vertical layers, depending on the water depth, with output at standard Levitus depth levels. Daily data are available from 3 November 2003 to three days into the future (Chassignet et al., 2009). On April 21, 2005, the US Minerals Management Service (MMS) issued a Notice to Lessees and Operators (NTL) regarding the reporting of ocean current data in the deep water of Gulf of Mexico. Since then, the offshore oil and gas industry has collected and reported current data, using Acoustic Doppler Current Profilers (ADCPs), at 78 deep water drilling locations in the Gulf of Mexico. The extensive body of NTL ADCP current data has been made available via the National Oceanic and Atmospheric Administration (NOAA) National Data Buoy Center (NDBC) web site1. This provides an extremely valuable source of observational data for model validation at deepwater drilling locations in Gulf of Mexico. Based on the results of the HYCOM validation in the Gulf of Mexico, this study assesses the suitability of the model for application by the offshore industry in the Gulf of Mexico.