Variability of the Deepwater Horizon Surface Oil Spill Extent and Its Relationship to Varying Ocean Currents and Extreme Weather Conditions - Mathematical Modelling and Numerical Simulation of Oil Pollution Problems - page 20

were used to provide useful representations of the current fields. These observations,
combined with the other satellite measurements and data from drifting buoys, pro-
vided a comprehensive view of the surface circulation dynamics. At the time of the
oil spill, the core of the LC exhibited a northern extension (approximately 28 ⓦ N),
around 150km from the oil spill site. At that time, this condition was hypothesized
to have the potential of connecting waters, and probably oil particles, from the oil
spill neighbouring areas into the central and southeastern GOM regions and beyond.
Results obtained here indicate that surface currents, from the Loop Current, a Loop
Current ring, and a cyclonic eddy, appeared to have controlled the southern and
eastern extent of the surface oil during May and June. On the other hand, intense
southeast winds associated with Hurricane Alex caused a reduction of the surface oil
extent at the end of June and beginning of July, as oil was driven onshore and mixed
underwater.
Results shown here represent a fraction of the combined DWH monitoring efforts
and they clearly exemplify the key role that satellite observations and numerical
model outputs play to monitor and analyse parameters critical for environmental
studies at scales where in situ observations are not adequate or possible. For example,
mesoscale features linked to the areal extent of surface oil confirm the important
value of real-time eddy permitting satellite altimetry, along with SAR, IR and visible
ocean colour data. This combination of active and passive satellite observations
shows the utility of joint satellite data analysis for surface oil extent monitoring and
studies. Although satellite observations serve to monitor surface parameters, in situ
hydrographic observations and numerical modelling efforts are needed to obtain a
subsurface assessment of the ocean conditions.
Results presented here also show the importance of extreme weather events in
the oil spill areal extent, indicating that atmospheric ocean couple models may be
necessary to properly monitor oil spacial extent.
Acknowledgments Funding for GG, JT, DS, and AMF was provided by NOAA. MJO was sup-
ported by NSF grant CMG0825547 and by a grant fromBP/The Gulf of Mexico Research Initiative.
JFM was partly funded by NASA grant NNX08AL60G, by a grant from BP/The Gulf of Mexico
Research Initiative. We would also like to acknowledge the work of Mr. Gregory Gawlikowski
(Roffer's Ocean Fishing Forecasting Service, Inc.) on mapping the distribution of oil and ocean
frontal analyses, and to Dr. Francis Bringas for his support on numerical computations and dis-
tribution of fields of ocean currents through the NOAA/AOML web site. MAR was funded by
Roffer's Ocean Fishing Forecasting Service, Inc., NASA Grant NNX08AL06G and University of
Miami Cooperative Institute for Marine and Atmospheric Studies Grants NA10OAR432143 and
R1100291, Florida Institute of Oceanography - University of South Florida grant 4710-1101-04.
University of Miami CSTARS provided the SAR data. Altimetry sea height data are from AVISO.
The information in this document reflects the views of the authors, and does not necessarily reflect
the official positions or policies of the National Oceanic and Atmospheric Administration or the
United States Department of Commerce.