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Environmental Stewardship
Meteorology and Air
Quality Studies
The MMS has regulatory
responsibility for OCS air quality in the Western and Central Gulf of
Mexico. To fulfill the regulatory responsibility, the onshore air
quality impacts from OCS offshore oil and gas activities must be
determined. The ESP has supported the collection of air quality and
meteorological data as well as impacts assessment modeling efforts to
evaluate these contributions.
Emission Inventories
A series of Gulf of Mexico Emission Inventory Studies
have been conducted since 1995 (volume
1,
volume 2,
volume 3) that include
2000,
2005 and
2008 Emission Inventory Studies. In
addition to these inventories, a synthesis, analysis, and integration of
air quality and meteorological data for the Gulf of Mexico region from
direct observations was compiled (volume
1,
volume 2,
volume 3, and
volume 4). These
data are used to evaluate the contributions from the OCS to coastal air
quality and the inventories are timed to be incorporated in State and
Federal efforts to evaluate air quality.
Direct Observations
The MMS has deployed cutting edge instruments on two
offshore platforms to obtain direct measurements of the vertical
structure of the marine boundary layer in the Central Gulf of Mexico.
Standard meteorological stations at the platforms provide surface data
by measuring air and water temperatures, pressure, winds and humidity.
The Radar Wind Profilers and Radio Acoustics Sounding System provide
wind and temperature profiles for the upper atmospheric layer. The data
were transmitted hourly from each platform via Geostationary Operational
Environmental Satellite to the NESDIS/NOAA facility on Wallops Island,
Virginia. These data not only supported MMS’ information needs but were
also distributed directly to the National Weather Service/NOAA in real
time for weather forecasts. The
meteorological data
provided the MMS with a description and analysis of the Atmospheric
Boundary Layer and how its structure influences the dispersion and
transport of pollutants in the Western and Central Gulf of Mexico. The
results support techniques for evaluating the effects of OCS oil and gas
exploration, development, and production activities on coastal air
quality.
The Radar Wind Profilers were redeployed at two
coastal locations to provide additional information about the lower
atmosphere. One profiler is located at the
Louisiana Marine Consortium facility in
Cocodrie, Louisiana. The data collected at this site is being used to
evaluate air quality conditions at the Breton Wildlife National Refuge
and southern Louisiana. The Refuge is a Class I area for
air quality. The second profiler system is
located at the
University of Houston Coastal Center
in Galveston County. Data from this profiler is used to evaluate air
quality in the Houston area and south Texas.
Meteorology Studies
Wind is an important forcing function in predicting
the dispersion of air pollutants and deriving ocean circulation for oil
spill risk analysis. Field observations and modeling efforts to
describe physical processes and provide long term forcing data have been
conducted in different regions. For example, the MMS deployed,
maintained, and
collected data from
five meteorological stations along the Beaufort Sea, Alaska from 2001
through 2005.
The
Beaufort Sea Mesoscale Meteorology
study began with a literature review to determine the most appropriate
meteorological model that would best support MMS objectives. Based on
the review, the Weather Research and Forecasting (WRF) model was
selected. The model’s performance in simulating the wind field was
analyzed, with emphasis placed on evaluating the capabilities of WRF to
accurately simulate the sea breeze and topographic effects. The WRF
model was then used to simulate Beaufort and Chukchi seas’ surface wind
and associated mesoscale meteorology. The final products include a
30-year (1979-2009) observational database; a 5 and 30-year hindcast
simulation of the Beaufort/Chukchi seas; as well as a final report
documenting the observational database quality control methods, final
model sensitivity analysis, and climatological analysis of both the
collected observations and long-term model simulation.
The MMS is preparing to
collect meteorological and wave measurements
from a platform in the Gulf of Mexico to improve the application of
meteorological and air quality models in the offshore environment and
the coastal area.
Other Air Quality Studies
A deposition study
was conducted that showed that Iodine from the microalgae in the sea
surface in coastal area can affect atmospheric chemistry through the
titration reaction of ozone and iodine as well as photochemical
reactions involving chlorine, iodine and other halogens from
phytoplanktons in the coastal waters. In addition, iodine and other
halogens in the air involve homogeneous and heterogeneous reactions with
anthropogenic and natural emissions that subsequently change
concentrations of ozone and atmospheric particular matter. Present
regulatory ozone modeling often fails to account for these effects in
the coastal waters and such omission can lead to the overestimation of
the impact of offshore oil and gas generation operations when developing
the state implementation plans for the new eight-hour ozone standard.
The first part of the study demonstrated that the changes in the ozone
deposition flux to the ocean surface due the sea surface processes can
play an important role in the ozone budget in the coastal boundary layer
and influence onshore and inland distribution of ozone. The second part
of the study involved development of iodine-extended atmospheric
chemistry module in CMAQ and quantification of ozone loss and production
budget in the Gulf of Mexico coastal boundary layer.
The Aura Satellite
study was conducted to ascertain the value of using satellite data to
specify ozone background values over the Gulf of Mexico, one of the
areas of uncertainty in air quality modeling assessments of OCS air
quality impacts. This study we utilized OMI ozone profiles together with
MODIS aerosol products to improve the representation of the chemical
atmosphere in the MM5/CMAQ air quality modeling system. The simulations
were performed for August 2006 over the continental United States and
evaluated against surface, ozonesonde, and satellite observations.
The Satellite Data
Assimilation study was performed to provide an improved representation
of the physical atmosphere, of utmost importance in air quality studies,
especially in regions such as Gulf of Mexico (GoM) where sea-breeze
circulations play an important role in the air quality of the coastal
areas, better representation of meteorology is imperative. The results
indicated GOES-derived skin temperature, insolation, surface albedo,
cloud albedo, and cloud top temperature can improve the predictions of
the MM5/CMAQ air quality modeling system. GOES-derived products were
assimilated in MM5 to recover moisture availability and heat capacity
over the south-central U.S. Also GOES observed cloud information is used
to adjust photolysis rates within CMAQ. |
