||National Oceanic and Atmospheric Administration, Washington, DC.; Environmental Protection Agency, Washington, DC.; Executive Office of the President, Washington, DC. Office of Science and Technology Policy.
This report presents a preliminary analyses of data collected by the R/V Brooks McCall near the site of the Deepwater Horizon MC252 (DWH-MC252) wellhead between May 8 and May 25, 2010. During this timeframe the DWH-MC252 wellhead was releasing gas and oil in a turbulent mixture from the broken riser pipe attached to the well. Throughout the data collection period, a plume of oil and gas continually rose from the wellhead with some oil reaching the surface in about three hours. During the trip to the surface, it is expected that some of the oil dissolved in the water column and some formed droplets. The pressure that propelled the oil out of the wellhead was strong enough to cause some of the oil to form water-in-oil emulsion, or mousse. The results from measurements below the sea-surface mixed layer of approximately 150 m were examined by the Joint Analysis Group (JAG) to determine if there was evidence of subsurface oil and, if so, the concentration, location, and extent of that oil. Experimental data and simulation models of subsurface releases indicated that oil from the DWH-MC252 release would be expected at depth. The JAG was recognized formally by the National Incident Command (NIC) on June 8, 2010, subsuming work that had been proceeding on an ad hoc basis motivated by the need to synthesize available information on subsurface sampling. The JAG operated at two levels for the production of its findings. For purposes of information exchange and metadata development, the group includes industry representatives responsible for providing data from contracted ships. For the purposes of final report development and approval of findings, just the federal agency representatives are involved. This report is the first in an anticipated series of data products from the JAG concerning data from the spill related to subsurface sampling.