Winter Ozone AQ Modeling Results

Approach

The WAQS modeling team conducted a series of CAMx sensitivity simulations off of 3SAQS Base 2011 version A (CAMx_3SAQS04_B11a) 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 adjusted oil and gas emissions and the WRF winter meteorology. The WAQS modelers adjusted the WRFCAMx processor to use the same vertical layer structure as WRF within the first 6 model layers. In all of the previous simulations (base, winter met, oil and gas emissions) the first 6 WRF layers were collapsed into the 3 CAMx layers such that WRF layers 1+2 = CAMx layer 1, WRF layers 3+4 = CAMx layer 2, and WRF layers 5+6 = CAMx layer 3. This collapsing roughly amounted to 12 m deep WRF layers being collapsed to 24 m deep CAMx layers. In the vertical mixing sensitivity the WRF vertical layer structure was preserved for the first 6 layers resulting in 28 layer CAMx meteorology (compared to 25 layer meteorology in the previous runs). Note that there was still layer collapsing applied above the first 6 WRF layers.

Simulation Summary:

Base Simulation
Simulation ID: CAMx_3SAQS04_B11a
Modeling Period: February 1-March 31, 2011
Analysis Domain: 4-km

Meteorology Sensitivity
Simulation ID: CAMx_3SAQS04_B11a_WinterO3
Met: WRF Winter + WRFCAMx Snow 25 layers
Emissions: Same as CAMx_3SAQS04_B11a

Oil and Gas Emissions Sensitivity
Simulation ID: CAMx_3SAQS04_B11a_WinterO3_OG_Emis
Met: Same as CAMx_3SAQS04_B11a_WinterO3
Emissions: 2x O&G VOC, 10x O&G HCHO, 0.5x O&G NOx adjustments to CAMx_3SAQS04_B11a

Vertical Transport Sensitivity
Simulation ID: CAMx_3SAQS04_B11a_WinterO3_OG_Emis_Layers
Met: WRF Winter + WRFCAMx Snow 28 layers (no collapsing in layers 1-6)
Emissions: Same as CAMx_3SAQS04_B11a_WinterO3_OG_Emis

Results

The results of the winter O3 modeling simulations are shown first as high level summaries of the domain wide performance and then as site-level performance plots.

4-kmPerformance Domain-Wide PerformanceSummaries

SimID Correlation        FB        FE        Max_mod        Max_obs        MB        ME        Mean_mod        Mean_obs        Min_mod        Min_obs        NMB        NME        R_Sq        RMSE Base11a       0.59       3.16       29.9       72       149       0.79       9.07       39       38.2       0       0       2.07       23.7       0.348       13.2 WinterO3       0.61       -10.7       32.3       70.2       149       -4.19       9.37       34       38.2       0       0       -11       24.5       0.372       13.1 OG_Emis       0.63       -4.71       30.1       114       149       -2.54       8.95       35.6       38.2       0       0       -6.66       23.4       0.397       12.3 Layers       0.64       -3.23       29.5       99.2       149       -1.74       8.64       36.4       38.2       0       0       -4.55       22.6       0.41       12.2

AQS Hourly O3 sites in the 4-km Domain

AQS Hourly NO2 sites in the 4-km Domain

Upper Green River Basin, WY Hourly O3 sites

Upper Green River Basin, WY Hourly NO2 sites

AQS Hourly O3 sites in the 4-km Domain

Soccer Plots by Site

Timeseries Analysis

Colorado

Utah

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

Site	Lat, Long, Elev	2011 Episode Dates	1-hr O3 Concentrations	Time-Height
Altamount	40.3603, -110.2858, 1949.8056	Feb 14	>85 ppb	WRF-Winter
		Mar 2-3	>85 ppb	WRF-Winter
Cedarview	40.383524, -110.072563, 1692.2496	Jan 7-8	>80 ppb
		Jan 25-31	>90 ppb
		Feb 12-16	>135 ppb	WRF-Winter
		Feb 23-24	>100 ppb
		Mar 1-3	>90 ppb	WRF-Winter
Dinosaur	40.4371, -109.3047, 1462.7352	Jan 6-9	>80 ppb
		Feb 12-16	>110 ppb	WRF-Winter
Duchesne	40.1615, -110.4011, 1682.496	Jan 29-30	>90 ppb
		Feb 12-16	>120 ppb	WRF-Winter
Horse Pool	40.1437, -109.4672, 1569.4152	Jan 6-8	>100 ppb
		Jan 24-31	>95 ppb
		Feb 12-16	>130 ppb	WRF-Winter
		Feb 23-25	>120 ppb
		Mar 1-4	>115 ppb	WRF-Winter
Jensen	40.3671, -109.3522, 1450.848	Feb 12-16	>100 ppb	WRF-Winter
		Feb 23-24	>80 ppb
		Mar 1-2	>80 ppb	WRF-Winter
Lapoint	40.404, -109.8157, 1673.9616	Jan 6-8	>90 ppb
		Jan 27-31	>80 ppb
		Feb 12-16	>120 ppb
		Feb 22-24	>100 ppb
		Mar 1-3	>85 ppb
Ouray	40.054768, -109.688001, 1463.9544	Jan 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 Draw	40.03460278, -109.8300556, 1466.6976	Feb 11-16	>140 ppb
		Feb 22-25	>120 ppb
		Mar 1-3	>110 ppb
Rabbit Mountain	39.8687, -109.0973, 1878.7872	Jan 16	>85 ppb
		Feb 14-16	>100 ppb
Red Wash	40.1972, -109.3525, 1688.8968	Jan 6-9	>95 ppb
		Jan 26-31	>95 ppb
		Feb 12-15	>135 ppb
		Feb 23-24	>105 ppb
		Mar 1-3	>100 ppb
Roosevelt	40.30073056, -109.9784172, 1544.7264	Jan 6-9	>80 ppb
		Jan 27-31	>100 ppb
		Feb 12-16	>120 ppb	WRF-Winter
		Feb 3-4	>100 ppb
		Mar 1-3	>80 ppb
Vernal	40.443273, -109.560983, 1662.684	Jan 8-9	>85 ppb
		Feb 12-16	>100 ppb	WRF-Winter
		Feb 24	>85 ppb
		Mar 2	>80 ppb

Wyoming

Site	Lat, Long, Elev	2011 Episode Dates	8-hr O3 Concentrations	Obs Y/N
Wyoming Range	42.98, -110.35, 2475	Feb 15	>80 ppb	Y
		Mar 10	>80 ppb
Pinedale	42.92, -109.79, 2388	Mar 1-2	>85 ppb	Y
		Mar 5	>80 ppb
Juel Springs	42.37, -109.56, 2144	Mar 2	>90 ppb	Y
		Mar 12	>85 ppb
		Mar 15	>85 ppb
Daniel	42.79, -110.05, 2173	Mar 10	>80 ppb	Y
Boulder	42.71, -109.75, 2160	Feb 14	>85 ppb	Y
		Mar 1-5	>120 ppb
		Mar 12	>120 ppb
Mobile Trailer	42.68, -109.8, 2143	Feb 14	>80 ppb	Y
		Mar 3	>80 ppb

Emissions Adjustments

O&G Basin Emission Adjustment Factors

Basin	NOx	VOC	CH4	Notes	Reference
Denver-Julesberg		>2.0			Petron et al., 2012
Piceance
North San Juan
South San Juan
Paradox
Uintah	0.25	1.6	4.4	Uintah and Duchesne Counties	Karion 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 Piney	VOC	CH4
Boulder	VOC	CH4	Winter VOC	Winter CH4	Winter NO2	Hourly CH4	Hourly NO2
Gillette	VOC	CH4
Pavilion	VOC	CH4	Winter VOC	Winter CH4	Winter NO2
Wamsutter	VOC	CH4

Monitoring Maps