Slide 1OutlineIntroduction to OCDHow was OCD developed?How does OCD work?Overland vs. OverwaterApplicationsWhat data is needed?Importance of meteorological data measurementsSome DefinitionsInstallationUsing OCDStarting a New ModelInput MenuRun InformationModel DomainSourcesDispersionReceptorsTypes of ReceptorsMeteorologySources of Meteorological DataChemical TransformationOutput OptionsDisplay Map of Shoreline, Sources, and ReceptorsRunning the programRunning the programCase Study: Deepwater HorizonSummaryThank you!Offshore and Coastal Dispersion (OCD) ModelHeather GroceOutlineI. IntroductionII. Methodology and ApplicationsIII. InstallationIV. UseV. Case StudyVI. SummaryIntroduction to OCDSimulates offshore emissions from point, area, or line sources to receptors on land or waterHourly, steady-state Gaussian modelQ: Why is it necessary to have a model specifically dedicated to a pollutant traveling from over water to over land?How was OCD developed?In 1980, a model was needed that would handle off-shore emissionsAdapted from MPTERThis model added overwater plume transport and dispersionAlso incorporated changes as plume crosses shorelineHow does OCD work?Three major components:Overwater subroutines that are new algorithms based on overland boundary layer dynamicsOverland subroutines from MPTERSubroutines from existing models to describe dispersion in complex terrainOverland vs. OverwaterOverwater mixing height is less than overland mixing height (why?)Overwater mixing depth can vary from 100 m to 500 mDifferent variations during the day and yearApplicationsWhat data is needed?Domain of model and defined coastMeteorological data (e.g. wind speed)Source data (e.g. emission rate)Receptor data (e.g. elevation)Importance of meteorological data measurementsOnsite overwater meteorological data (hard to obtain)Representative overwater meteorological dataRepresentative overland meteorological dataWind speed and directionMixing heightOverwater air temperatureRelative humiditySea surface temperatureSome DefinitionsInstallationCode can be downloaded from the EPA’s Preferred/Recommended Models webpageUser-friendly interfacehttp://www.epa.gov/ttn/scram/dispersion_prefrec.htmUsing OCDStarting a New ModelInput MenuNine input windows:Run InformationModel DomainSourcesNew Inputs:•Stack angle from the vertical•Height of stack top above its base*•Height of building at or near stack baseDispersionReceptorsTypes of ReceptorsDiscretePolarCartesianMeteorologySources of Meteorological DataASCII, included in Control FileBinary, in Separate PCRAMMET FileASCII, in Separate PCRAMMET FileChemical TransformationOutput OptionsDisplay Map of Shoreline, Sources, and ReceptorsRunning the programRunning the programThe hourly emission file is the only optional data.Case Study: Deepwater HorizonSummaryThank