AERMOD Future Development: White Paper Recap. R. Chris Owen, Roger Brode, Clint Tillerson, James Thurman, George Bridgers OAQPS/AQMG 6/5/2018

Transcription

1 AERMOD Future Development: White Paper Recap R. Chris Owen, Roger Brode, Clint Tillerson, James Thurman, George Bridgers OAQPS/AQMG 6/5/2018 1

2 Treatment of Low Wind Conditions

3 New LOW_WIND Keyword Options Minimum σ v value. The default value in AERMOD is 0.2 m/s. LOWWIND1 used a value of 0.5 m/s, LOWWIND2 and LOWWIND3 used a value of 0.3 m/s. Plume meander/upper limit of FRAN. The default upper limit in AERMOD is 1.0, while LOWWIND2 set this value at Minimum wind speed. The default value in AERMOD is m/s, consistent with the default applied in previous versions based on SQRT(2*SVmin*SVmin) with SVmin=0.2. While this value was not adjusted in any of the LOWWIND packages, the minimum wind speed can be adjusted under the existing LOW_WIND keyword. 3

4 Options NOT included in the LOW_WIND Elimination of upwind dispersion Elimination of horizontal meander Adjustments to FRAN will mimic this Adjustment to the BIGT parameter FASTALL approach to match plume centerline concentrations FASTALL is still an option in AERMOD and can be used independently of the LOW_WIND keyword 4

5 Accompanying LOW_WIND White Papers Minimum value for lateral turbulence (aka, minimum σ v ) Issues Related to Plume Meander in the AERMOD System FRAN BIGT Upwind dispersion 5

6 Updates for Mobile Source Modeling

7 RLINE Integration RLINE is a LINE source model, developed ORD. AERMOD s current LINE source uses the AREA source formulation RLINE uses state-of-the-art Gaussian dispersion algorithms, similar to AERMOD. Contains a true line source algorithm based on Romberg integration of point sources (Snyder et al., 2013a). Tailored to roadway applications, adds plume meander under low wind conditions. 7

8 Barriers and Depressed Roadways RLINE has developmental implementation of solid barrier and depressed roadway algorithms for modeling complex roadway configurations. Still under development by ORD. Need evaluation and peer-review. 8

9 Next Steps for Mobile Sources RLINE likely to be available as a beta option in 2019 release of AERMOD Barrier and depressed roadways also likely available, but as alpha options EPA working with external community to identify opportunities for field studies for model evaluation Solid barriers primary focus, currently an RFP out from CALTRANS for a roadway barrier tracer study 9

10 Updates for NO 2 Modeling

11 New Tier 3 Model Development API working with CERC to implement a version of the ADMS NO 2 scheme into AERMOD Similar to PVMRM in that it accounts for plume volume and considers entrainment of ozone Adds post-chemistry (equilibrium calculation), i.e., conversion of NO 2 back to NO Computation incorporates background NO x concentrations Draft version delivered to EPA in June, 2015 Carruthers et. al., 2017 peer reviewed journal article Provides scientific review of methodology Includes model performance evaluation Potentially available in the next EPA update to AERMOD, depending on delivery of most recent version to EPA 11

12 Evaluation database development Stationary sources Kuparuk, Alaska Drill Rig Denver-Julesburg Basin, Colorado Drill Rig BLP, API, EPA, AECOM, ERM, City of Denver Oklahoma Compressor Station PRCI, API, other industry groups Near-road Las Vegas, Nevada Detroit, Michigan EPA, FHWA 12

13 New Tier 2 Development Considering a new Tier 2 screening method for NO2 Based on the time it takes for NO to react with O3 to form NO2 Reaction rate on the scale of 1-3 minutes, could be important for fenceline concentrations Under development! Will evaluate with the new NO2 databases Complete conversion time (minutes) NO conversion times based on ozone concentration t = *[O3] -1 R² = ozone concentration (ppb)

14 Overwater Dispersion Modeling

15 Necessary Science Updates to AERMOD Platform Downwash AERMOD needs to be updated to account for downwash effects that are unique to offshore platforms which are raised, often open lattice structures. PRIME downwash algorithms in AERMOD were designed for solid, rectangular, groundbased buildings. Shoreline/Coastal Fumigation AERMOD needs to be updated to include shoreline/coastal fumigation AERMOD accepts only one set of boundary layer meteorology for the entire modeling domain. Marine Boundary Layer Parameterization Boundary layer parameterization in AERMOD is land-based A different parameterization scheme is needed to better represent the marine boundary layer in AERMOD (e.g., sea surface temperature)

16 Current and Planned Initiatives IWAQM agreement with the Dept. of Interior s Bureau of Ocean and Energy Management (BOEM) Leverage on-going work on downwash from ORD and PRIME2 committee Evaluation of screening algorithms in AERSCREEN and SCREEN3, and the Shoreline Dispersion Model (SDM), along with more recent published research. AERCOARE preprocessor for overwater meteorological data available as a counterpart to AERMET to better characterize the marine boundary layer for offshore sources. Additional testing and evaluation of AERCOARE and consider incorporating the COARE algorithms into AERMET.

17 Saturated Plumes

18 Summary of Saturated Plume Issue NOx and SOx controls can add heat and moisture to stack effluent Condensation of moisture in these plumes can increase plume rise Plume rise is considered for POINT sources in AERMOD Calculation accounts for both momentum and buoyancy Buoyancy is based on exit temperate and does not consider any additional heat inputs, i.e., the heat of condensation PLURIS is generic plume rise model that can be applied to situations with arbitrary three-dimensional wind fields, arbitrary directions of the source exit, and to both dry and wet plumes Janicke, U., Janicke, L.: A three-dimensional plume rise model for dry and wet plumes. Atm. Env. 35, 2001 Paine et al., 2016, recommend a pre-processor to adjust POINT source temperature to account for additional buoyancy from condensation Currently no model performance evaluation of the suggested pre-processor

19 Emerging Issue: Buoyant Plumes

20 Summary of Buoyant Line Plume EPA incorporated the Buoyant Line Plume (BLP) model into AERMOD as part of the 2017 Appendix W update BLP was integrated as is, with no scientific changes AERMOD met is converted to PG stability class for BUOYLINE calculations in AERMOD BLP was formulated for roof vents, mainly for smelter facilities Plume rise from these sources includes buoyancy only, i.e., no momentum BLP considers wind-angle specific entrainment, such that plume rise can be enhanced when winds are parallel to vents BLP has been applied in various ways for other long and hot sources

21 Other pieces of buoyancy POINT sources include buoyancy in plume rise calculations Buoyancy is reduced relative to a buoyant line source Buoyancy flux formula is essentially the same among the various models Subsequent plume rise and dispersion coefficients in BLP and AERMOD are distinctly different, though Recent and historical efforts by facilities to use hybrid methods to maximize return on scientific features Enhanced plume rise from BLP, better dispersion estimates from AERMOD POINT/AREA sources Buoyancy from fugitives could be important for some sources Buoyancy from generally hot facilities, even if not the specific emissions themselves, could be important for some sources

22 Emerging Issue: theta*, et al.

23 theta*, THSTAR, Ɵ* THSTAR is a parameter that influences the temperature lapse rates in AERMOD under stable conditions; The calculation of THSTAR may depend on other options, e.g., use of the ADJ_USTAR option; For applications including multi-level temperature profiles AERMOD calculates THSTAR based on the observed profiles; THSTAR is calculated in both AERMET and AERMOD: Some consideration of passing the THSTAR value from AERMET to AERMOD Some anomalously high lapse rates in some applications, especially when L is small.