Environmental Engineering Reference
In-Depth Information
1.1 Introduction
A major crude oil spill occurred following an explosion aboard the Deepwater
Horizon (DWH) drilling platform in the northern Gulf of Mexico (GOM) on April
20, 2010. This spill differed from other significant oil spill events in that it was the
largest accidental oil spill in US history [
19
]. It occurred in the open ocean at a depth
of 1500m, and both oil and dissolved oil had the potential to affect distant areas
of the GOM at the ocean surface and subsurface. This spill occurred in a signifi-
cant ecosystem that supports major fisheries, and numerous endemic and migrating
populations of fish, reptiles, birds, marine mammals, plankton and various sensitive
benthic communities. A very large effort was initiated and sustained by the scientific
and operational communities of the nations bordering the GOM to assess the extent
to which oil was spreading. The oil continuously entered the deep GOM between
late April and the time of final capping on July 15, 2010, spreading by means ocean
and wind forcing at the surface and subsurface [
16
].
A suite of satellite-derived products and analyses were developed and generated
in real time to address the need to observe the synoptic scales of the spill which
is critical to assess numerical model outputs. The satellite data and products were
provided through joint government, academic, and private sector partnerships to help
the operational community with its response efforts to task and direct oil-spill clean-
up and recovery-related efforts. These satellite data and their derived products served
as a critical complement to observations collected from field programs and, at times,
provided the only available observations and products to perform rapid estimates of
a number of environmental parameters over large geographic areas. For example,
these observations proved to be critical for real-time analysis and assessment of the
GOM conditions to: (a) Monitor the extent and variability of the oil spill at the ocean
surface; (b) Assess the surface circulation that could create surface oil pathways
and boundaries to the surface oil extent; (c) Monitor surface winds that could force
the motions of oil and water; and (d) Initialize and validate numerical models. This
chapter provides a review of the extent of the surface oil and of the upper ocean
dynamic conditions (a through c) as observed using a suite of satellite observations,
analyses, and products, during the 2010 DWH oil spill.
Satellite and in situ observations were used to monitor the variability of the extent
of the surface oil. Aircraft overflights with observers and a wide collection of sensors,
such as side-looking airborne radar and infrared and hyper-spectral sensors, were
used to complement and validate the satellite observations and to provide additional
details about oil location, oil thickness, and areal coverage. Some of these datasets
will take years to process to fully exploit their information content. The large areal
extent of the spill, however, precluded aircraft mapping of the entire surface oil area.
Therefore, the integration of aircraft and satellite data provided an overview of the
spill that neither observational platform could achieve alone. In addition, satellite
monitoring was also used to assess whether and how upper ocean dynamics were
conduits for the long distance transport of water and oil particles to areas far removed
from the oil spill source. This was particularly important early in the spill. There were
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