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Winter Ozone AQ Modeling Results

Abstract

The WAQS modeling team conducted a series of CAMx sensitivity simulations with the objectives of understanding the deficiencies and improving the ability of the model in reproducing high wintertime ozone concentrations related to localized meteorological conditions and oil and gas emissions sources. The WRF Winter Modeling Workplan and WRF Winter Modeling Evaluation Report describe our efforts to improve the simulation of the meteorology associated with high wintertime ozone. The WRF modeling conducted by the WAQS team resulted in a wintertime WRF configuration that results in a better model of the inversion events that accompany high ozone concentrations.

The WAQS modelers conducted a CAMx simulation with the new winter meteorology (and additional improvements to the way CAMx simulates snow albedo and chemistry). The changes to the meteorology did little to improve the CAMx under predictions of high wintertime ozone. Using insights from top down modeling and observational campaigns in Intermountain West oil and gas basins, the WAQS team developed a brute force oil and gas emissions sensitivity to test the hypothesis that our simulations underpredict VOC emissions and overpredict NOx emissions from oil and gas sources. The second winter O3 sensitivity used the same meteorology inputs as the winter meteorology simulation and included the following adjustments to the emissions from oil and gas sources (both area and point): 2x VOCs, 10x formaldehyde, and 0.5x NOx. While the emissions perturbation produced improvements at some monitoring locations at some times, there were still high ozone events that were badly underpredicted by the model.

The final CAMx sensitivity simulation conducted by the WAQS modelers was designed to test the hypothesis that there was still to much dilution in the surface layer of the model. The winter ozone layer sensitivity used the same adjusted emissions as the previous sensitivity and the same WRF configuration. The WAQS modelers adjusted the WRFCAMx processor to use the same vertical layer structure

Emissions Adjustments

O&G Basin Emission Adjustment Factors

BasinNOxVOCCH4NotesReference
Denver-Julesberg >2.0  Petron et al., 2012
Piceance     
North San Juan     
South San Juan     
Paradox     
Uintah0.251.64.4Uintah and Duchesne CountiesKarion et al., 2013; Ahmadov et al., 2015
Southwest Wyoming     
Big Horn     
Wind River     
Powder River     
Great Plains     
Williston     
3SAQS Sensitivity will use 2.0x VOC and 0.5x NOx across the board for area and point O&G sectors.

Upper Green River Basin CAMx Analysis

WYDEQ Hourly VOC Sites

Monthly Average Concentrations

Big PineyVOCCH4
BoulderVOCCH4Winter VOCWinter CH4Winter NO2Hourly CH4Hourly NO2
GilletteVOCCH4
PavilionVOCCH4Winter VOCWinter CH4Winter NO2
WamsutterVOCCH4

Timeseries Analysis of CAMx Base11a O3

Colorado

Utah

Uintah Basin Winter Ozone Study
These sites only measured ozone and meteorology parameters

SiteLat, Long, Elev2011 Episode Dates1-hr O3 ConcentrationsTime-Height
Altamount40.3603, -110.2858, 1949.8056Feb 14>85 ppbWRF-Winter
  Mar 2-3>85 ppbWRF-Winter
Cedarview40.383524, -110.072563, 1692.2496Jan 7-8>80 ppb 
  Jan 25-31>90 ppb
  Feb 12-16>135 ppbWRF-Winter
  Feb 23-24>100 ppb
  Mar 1-3>90 ppbWRF-Winter
Dinosaur40.4371, -109.3047, 1462.7352Jan 6-9>80 ppb 
  Feb 12-16>110 ppbWRF-Winter
Duchesne40.1615, -110.4011, 1682.496Jan 29-30>90 ppb 
  Feb 12-16>120 ppbWRF-Winter
Horse Pool40.1437, -109.4672, 1569.4152Jan 6-8>100 ppb 
  Jan 24-31>95 ppb
  Feb 12-16>130 ppbWRF-Winter
  Feb 23-25>120 ppb
  Mar 1-4>115 ppbWRF-Winter
Jensen40.3671, -109.3522, 1450.848Feb 12-16>100 ppbWRF-Winter
  Feb 23-24>80 ppb
  Mar 1-2>80 ppbWRF-Winter
Lapoint40.404, -109.8157, 1673.9616Jan 6-8>90 ppb 
  Jan 27-31>80 ppb
  Feb 12-16>120 ppb
  Feb 22-24>100 ppb
  Mar 1-3>85 ppb
Ouray40.054768, -109.688001, 1463.9544Jan 6-9>100 ppb 
  Jan 16-17>95 ppb
  Jan 26-31>105 ppb
  Feb 11-16>140 ppb
  Feb 24-25>120 ppb
  Mar 1-3>100 ppb
Pariette Draw40.03460278, -109.8300556, 1466.6976Feb 11-16>140 ppb 
  Feb 22-25>120 ppb
  Mar 1-3>110 ppb
Rabbit Mountain39.8687, -109.0973, 1878.7872Jan 16>85 ppb 
  Feb 14-16>100 ppb
Red Wash40.1972, -109.3525, 1688.8968Jan 6-9>95 ppb 
  Jan 26-31>95 ppb
  Feb 12-15>135 ppb
  Feb 23-24>105 ppb
  Mar 1-3>100 ppb
Roosevelt40.30073056, -109.9784172, 1544.7264Jan 6-9>80 ppb 
  Jan 27-31>100 ppb
  Feb 12-16>120 ppbWRF-Winter
  Feb 3-4>100 ppb
  Mar 1-3>80 ppb
Vernal40.443273, -109.560983, 1662.684Jan 8-9>85 ppb 
  Feb 12-16>100 ppbWRF-Winter
  Feb 24>85 ppb 
  Mar 2>80 ppb
Wyoming

SiteLat, Long, Elev2011 Episode Dates8-hr O3 ConcentrationsObs Y/N
Wyoming Range42.98, -110.35, 2475Feb 15>80 ppbY
  Mar 10>80 ppb
Pinedale42.92, -109.79, 2388Mar 1-2>85 ppbY
  Mar 5>80 ppb 
Juel Springs42.37, -109.56, 2144Mar 2>90 ppbY
  Mar 12>85 ppb
  Mar 15>85 ppb
Daniel42.79, -110.05, 2173Mar 10>80 ppbY
Boulder42.71, -109.75, 2160Feb 14>85 ppbY
  Mar 1-5>120 ppb
  Mar 12>120 ppb
Mobile Trailer42.68, -109.8, 2143Feb 14>80 ppbY
  Mar 3>80 ppb

Monitoring Maps

Zoom of 3-State O&G Basins

Uintah and Piceance Basins

Southwest Wyoming Basin