NC Air Quality Modeling Presented by Chuck Buckler, North Carolina Division of Air Quality November 12, 2012
Topics to be Discussed • NC Air Quality modeling Programs • Why alternative approach for AERMOD PSD meteorological data? • Why did we think the Texas approach was the best? • General NC process to accomplish met data selection and modeling
What Do We Conduct Air Quality Modeling? • National Ambient Air Quality Standards (NAAQS) • PSD Increment • Class 1 Visibility • Deposition of Particulate Emissions • State Air Toxic Programs • Risk Assessment • National Environmental Policy Act (conformity) • State Implementation Plan (SIP) Compliance • Risk Management Plans • Emergency Management • Evaluate Worker exposure
Why alternative meteorological data • Toxics vs PSD • Quarried numerous states • Reasonable, consistent, equitable and reviewable • Varied climate and terrain • Texas approach seemed to be clear and simple
Why was the Texas Approach the best? • AERMOD – With AERMOD we knew that the three new surface characteristics (Albedo, Bowen Ratio and Roughness Parameters) would need to be quantified. • North Carolina has many different climates and surface characteristics (Coastal, Piedmont, foothills and Mts.) and has several meteorological data stations and 4 potential upper-air sites. • This meant that we needed a manageable and reasonable approach for industry as it pertains to meteorological data.
Goals to a streamlined Met Data Set • Understand the key surface characteristics in AERMET preprocessor: • Albedo – Assign Vegetation types typical to regions within the state • Bowen Ratio - AERMET Requirement (Average noonday Bowen ratio, Not used for nighttime hours, Model is not very sensitive to small changes in Bowen Ratio in many cases) • Roughness parameter - Develop reasonable roughness values that will provide a reasonable representation (model) of the areas we are analyzing • Bottom line - Provide consistency in the modeling
NC Meteorological Data Selection Guidance • Select the appropriate meteorological data for the site using the county-by-county list of approved NWS sites from our website • Determine the surface roughness of the site (e.g. 1.0 (high), .5 (medium), and .05 (low)) by using the AERSURFACE preprocessor • DAQ provides a list of inputs (e.g. surface roughness radius, surface moisture, arid region, etc.)
NC Specific Modeling Requirements • Modeling Protocol – A document that ensures the applicant follows the approved modeling methods required by DAQ. • Modeling Protocol Checklist – a streamlined document that is submitted with the analysis showing DAQ that our modeling requirements have been met. • Plat Plan – A facility must submit this with the analysis to ensure the modeled receptors are located properly.