Eastern Gulf of Mexico Circulation Study: Overview of the Study Goals and Objectives, Measurements Obtained, and Preliminary Results

From January 2005 to January 2006, one year of current and C/T/P measurements from four moorings in water depths from 2500 to 2800 m located south of Mobile Bay, Alabama were obtained as part of the Eastern Gulf of Mexico Circulation Study for the US Minerals Management Service (MMS). The mooring measurements were supplemented with bottom-moored PIES, three hydrography (profiling CTD and XBT) cruises, and satellite imagery and altimetry. The purpose of the measurements was to document the deepwater circulation in this sparsely measured area, and to better understand the key processes controlling and energizing the circulation in this area of future oil and gas leasing. Anticipated key processes included: ldr Loop Current (LC) & Loop Current Eddy (LCE) intrusions & dynamicsLCE frontal cyclonic and anti-cyclonic eddies ldr Eddy-topography interactions ldr Potential TRW genesis & propagation ldr Interactions between upper & lower layers ldr Response to hurricanes and storms. The measurement program was designed to obtain an integrated set of current, hydrography, remote sensing, and ancillary measurements that could provide an excellent understanding of the circulation on both a regional scale (50 - 200 km), as well as small scale (10-25 km), under hopefully a variety of energizing conditions. The study experienced an incredibly robust set of circulation energizing events, and achieved excellent data return to document the effect of those events on the circulation. During the study year, a portion of the study area was impacted by the Loop Current or a Loop Current Eddy and related frontal features, at least five times. Even the northernmost mooring experienced a Loop-related feature at least twice for extensive periods. In addition, four hurricanes and one tropical storm passed close by or over the study area.