Numerical Circulation Model Skill Assessment from Observed Deepwater Currents Over 2 Years on the Continental Slope near the Macondo Spill Site

The Gulf Integrated Spill Research (GISR) Consortia deployed an array of six deepwater moorings on the DeSoto Slope and Mississippi Canyon Region from July 2012 to July 2014. Each mooring consisted of an upward looking 75kHz ADCP in the upper 1000 meters, three deep current meters from 15m above the bottom and spaced ~200m apart, as well as numerous sensors for temperature and salinity. The purpose of the GISR mooring array was to characterize variability along the slope in support of both near field plume modeling and a deep tracer release experiment. We compare the observational estimates from the mooring array to those predicted from a coupled ocean-atmosphere numerical circulation model of the Gulf of Mexico for July 2012 through July 2013; this corresponds to the first 13 months the mooring array was deployed. The comparison will include both the relative accuracy of the model in time, as well as long term statistics and means for the region. We report variability and transport estimates for volume, mass, and nutrients (using hydrography); as well as the model’s predictive capabilities within different portions of the water column in close proximity to the Macondo spill site. We place special focus on the model’s abilities in the midwater depths where the methane plume observed during the oil spill.