Interim WEP/AOI Analysis – April 2, 2020

Interim Weighted Emissions Potential (WEP) and Area of Influence (AOI) products are being made available for Regional Haze planning uses.  Remaining regional SMOKE emissions modeling is being conducted for the disaggregated California 2028 emissions. Once those disaggregated emissions are ready they will be combined with emissions from the other WRAP states to provide consistent and final Source Sectors’ data for the final WEP analysis, and the plots and this description will be updated as needed.

Interim WEP/AOI Products

The following link provides access to the interim WEP/AOI displays using the directory structure described below.

WEP/AOI Image Browser

WEP/AOI products are available for 76 IMPROVE sites that represent 116 Class I areas in the 13 WRAP contiguous and neighboring states in the western U.S.  The results are calculated for the 12WUS2 modeling domain aggregated to 36 kilometer resolution. For each Class I area there are four directories containing the various analysis products. The directory structure and analysis products are shown below using the Mesa Verde National Park (MEVE) results as an example:

├── MEVE

│   ├── RT

│   ├── EWRT

│   ├── WEP

│       ├── EC

│       ├── NOx

│       ├── POA

│       ├── SOx

│   └── RANK_POINT

 

Residence Time (RT):  The RT folder contains plots showing the Area of Influence (AOI) that back trajectories of air parcels traveling from a given location arrived at the Mesa Verde National Park (MEVE) Class I area IMPROVE site on the Most Impaired Days (MIDs) during each year of the 5-year period from 2014 through 2018.  HYSPLIT 72-hour back trajectories are calculated to arrive on each of the MIDs four times a day (6:00, 12:00, 18:00, 24:00 local standard time) and at four heights above the ground (100 m, 200 m, 500 m and 1,000 m). Plots are provided for the 100m and 1000m heights and for a combined analysis in which data from all trajectory heights are aggregated (All). RT plots for Mesa Verde National Park (MEVE) are provided as an example in Figure 1.

Figure 1.  Residence Time (RT) analysis for Mesa Verde National Park (MEVE) Class I area IMPROVE monitoring site and back trajectories that arrive at the site on the Most Impaired Days for each year 2014-2018 at 100 m (left), 1000 m (middle) and All (right) heights above ground.

 

Emissions Weighted Residence Time (EWRT):  EWRT are calculated by weighting the HYSPLIT trajectories by the monitored extinction at the IMPROVE site on each MID. Each Class I area EWRT folder contains 12 plots showing the extinction weighted for sulfate (Amm_SO4), nitrate (Amm_NO3), Organic Aerosol (OA) and Elemental Carbon (EC) at three heights (100 m, 1000 m, All) (12 = 3 x 4).  Figure 2 shows the EWRT plots for sulfate and nitrate at MEVE using the aggregated trajectory height analysis (All) as an example.

Figure 2.  Extinction Weighted Residence Time (EWRT) analysis for ammonium sulfate (Amm_SO4) and ammonium nitrate (Amm_NO3) at the Mesa Verde (MEVE) IMPROVE monitor for the Most Impaired Days during 2014-2018 aggregated across all trajectory heights.  

 

Weighted Emissions Potential (WEP):  WEP is obtained by overlaying the EWRT results with 2028 emissions of light extinction precursors (e.g., NOx emissions for ammonium nitrate extinction). The WEP folder contains four subfolders corresponding to the precursor emissions for four major components of light extinction: EC (Elemental Carbon), NOx (Ammonium Nitrate), POA (Organic Aerosol) and SOx (Ammonium Sulfate).  Each precursor species subfolder contains 18 plots in which the EWRT at three heights above ground are overlaid with 2028 emissions from 6 gridded Source Sectors (18 = 3 x 6). The source sectors are listed below, and example plots for MEVE are shown in Figure 3.

·         TOTAL_ANTRHO – All anthropogenic emissions

·         TOTAL_POINT – All point source emissions

·         EGU_noCA – Electrical Generating Unit point source emissions except those in California

·         ON-ROAD – On-road mobile source emissions

·         AREA – Low-level area source emissions (e.g., non-road, non-point oil and gas, other non-point, locomotive, and Category 1&2 marine vessels)

·         CMV_OGV – Large ocean-going vessels

Figure 3.  Weighted Emissions Potential (WEP) analysis for ammonium nitrate extinction at the Mesa Verde National Park (MEVE) Class I area IMPROVE monitor on the Most Impaired Days during each year of 2014-2018 for NOx emissions from four Source Sectors:  (1) total anthropogenic (top left), (2) total point source (top right), (3) EGU point source except California (bottom left) and (4) low-level area source (bottom right). Results are aggregated across all trajectories’ heights.

 

Rank_Point:  The Rank_Point folder contains six csv files that consist of facility level 2028 emissions for NOx or SOx sources overlaid with the corresponding EWRT for ammonium nitrate or ammonium sulfate, respectively, for 3 trajectory height scenarios (100m, 1000m and All).  The columns of the Rank_Point files are described in Table 1 below.

These results can be used to assess the potential contributions of specific facilities to visibility impairment at each Class I Area in various ways. The QoverD_NOX and QoverD_SO2 provide the simple emissions over distance metric (Q/D) using the 2028 OTB facility-level NOx and SO2 emissions, respectively.  While the Q/D metric can be used to screen the potential contributions of sources to visibility impairment at a given Class I area, it is simply based on the emission rate and distance from the IMPROVE monitor and does not account for the air parcel trajectories on the MIDs. Note that the Rank_Point QoverD metric is different than the Regional Haze Planning Workgroup (RHPWG) Control Measures Subcommittee (CMS) Q/D Analysis in that Rank_Point is using 2028OTB emissions, whereas the RHPWG/CMS Q/D Analysis used 2014 emissions.  [ADD HYPERLINK TO HIGHLIGHTED TEXT; http://views.cira.colostate.edu/tssv2/Emissions/QDAnalysis.aspx]

The EWRTxQ and EWRTxQ/D metrics for NOx and SO2 do account for the air parcel trajectories on MIDs as they are calculated by multiplying the EWRT of the grid cell of the facility with the facility’s emission rate (Q) and Q/D, respectively.

Table 2 shows a subset of the results for NOx sources at MEVE aggregated across all trajectory heights. The sources are ranked by [Q/D x EWRT] (last column) for ammonium nitrate and the top 30 facilities whose NOx emissions potentially contribute to visibility impairment on the 2014-2018 IMPROVE MIDs at MEVE are shown. 

Table 1. Column listing and description for the Rank_Point csv files.

Column

Description

FacilityID

Plant identification code

FacilityName

Plant name

Latitude

Latitude

Longitude

Longitude

State

State in which the plant is located. It is determined by FIPS code. If there is no value, plant is either on tribal land or in the ocean (e.g., offshore O&G platform)

NAICS

North American Industry Classification System (NAICS) - an industry classification system https://www.census.gov/eos/www/naics/

NAICSDesc

Description of NAICS code

NOX_tpy

2028OTB Facility-level NOx emission rate in tons pers year (Q in NOx Q/D calculations)

SO2_tpy

2028OTB Facility-level SO2 emission rate in tons per year

ij

The grid cell of the facility in the 12WUS2 modeling domain (aggregated to 36 km resolution). Format is row (i) *1000 + column (j).

distance

Distance in meters between the facility and the IMPROVE monitor that represents the Class I area (D in Q/D calculations). Distances are calculated using the Lambert Conformal Conic projection of the 12WUS2 modeling domain.

EWRT_NO3_IJ

The Amm_NO3 extinction weighted residence time (EWRT) for the grid cell of the facility (ij)

QoverD_NOX

The facility's NOx emissions (Q) in tons/year divided by the distance to the IMPROVE monitor (D) in kilometers.

EWRTxQ_NO3

The Amm_NO3 EWRT for the grid cell of the facility (ij) multiplied by the facility-level NOx emissions (Q)

EWRTxQoverD_NO3

The Amm_NO3 EWRT for the grid cell of the facility (ij) multiplied by the facility's Q/D for NOx (QoverD_NOX)

EWRT_SO4_IJ

The Amm_SO4 extinction weighted residence time (EWRT) for the grid cell of the facility (ij)

QoverD_SO2

The facility's SO2 emissions (Q) in tons/year divided by the distance to the IMPROVE monitor (D) in kilometers

EWRTxQ_SO4

The Amm_SO4 EWRT for the grid cell of the facility (ij) multiplied by the facility-level SO2 emissions (Q)

EWRTxQoverD_SO4

The Amm_SO4 EWRT for the grid cell of the facility (ij) multiplied by the facility's Q/D for SO2 (QoverD_SO2)

 

Table 2. Rank_Point results showing top 30 facilities ranked by [(Q/D) x EWRT_AmmNO3] whose NOx emissions have the potential to contribute to visibility impairment due to Ammonium Nitrate at MEVE on the Most Impaired Days for each year in 2014-2018.

FacilityID

FacilityName

State

NAICS

NAICSDesc

NOX_tpy

distance

QoverD

EWRTxQ

EWRTxQ/D

7197711

Four Corners Power Plant

0

221112

Fossil Fuel Electric Power Generation

4060.4

56621

71.7

17046392

301062

7230311

Kutz Canyon Processing Plant

NM

21112

0

751.6

74910

10.0

4706391

62827

1158

Kutz Canyon Processing Plant

NM

21113

0

677.3

75422

9.0

4241210

56233

3552

Blanco Compressor C & D Station

NM

48621

Pipeline Transportation of Natural Gas

504.0

69600

7.2

3156016

45345

7231911

Harvest Pipeline - San Juan Gas Plant

NM

21112

0

494.5

69341

7.1

3096578

44657

1177

Harvest Pipeline - San Juan Gas Plant

NM

21113

0

468.1

69262

6.8

2931213

42320

1148

Chaco Gas Plant

NM

21112

0

1098.6

85699

12.8

3488257

40703

1147

Blanco Compressor Station A

NM

48621

Pipeline Transportation of Natural Gas

378.6

69618

5.4

2370957

34057

14939211

Ignacio Gas Plant

0

211112

Natural Gas Liquid Extraction

243.1

62531

3.9

1766445

28249

14939111

Arkansas Loop Treating Plant

0

211112

Natural Gas Liquid Extraction

236.1

64222

3.7

1715581

26713

8091911

San Juan River Gas Plant

NM

21112

0

134.6

50009

2.7

1268501

25366

14936411

Coyote Gulch Gas Treating Plant

0

211111

Crude Petroleum and Natural Gas Extraction

53.5

43049

1.2

845074

19630

1192

Bloomfield Compressor Station

NM

48621

Pipeline Transportation of Natural Gas

216.6

70787

3.1

1356613

19165

14940411

Bondad CS

0

48621

Pipeline Transportation of Natural Gas

165.9

64511

2.6

1205686

18690

14938111

Jaques Compressor Station

0

211111

Crude Petroleum and Natural Gas Extraction

157.0

71789

2.2

1140814

15891

14937711

Worford Ridge Compressor Station

0

211111

Crude Petroleum and Natural Gas Extraction

135.5

68670

2.0

984588

14338

1191

Harvest - Thompson Compressor Station

NM

213112

Support Activities for Oil and Gas Operations

68.1

53141

1.3

641941

12080

14937211

South Ignacio Central Delivery Point

0

2111

Oil and Gas Extraction

128.8

77914

1.7

935904

12012

14940311

Animas compressor station

0

2111

Oil and Gas Extraction

88.4

53586

1.6

642344

11987

7992811

Val Verde Treatment Plant

NM

21112

0

133.1

69691

1.9

833206

11956

2579411

Florida River Compression Facility

0

2111

Oil and Gas Extraction

100.3

62833

1.6

728589

11596

8839911

El Paso Natural Gas, Window Rock Compressor Station

0

221210

Natural Gas Distribution

1354.1

184054

7.4

2042111

11095

1252

San Juan River Gas Plant

NM

21113

0

58.0

49851

1.2

546917

10971

14936311

Pump Canyon Compressor Station

0

2111

Oil and Gas Extraction

110.8

74053

1.5

805110

10872

17134211

Ignacio Gas Treating Plant

0

211111

Crude Petroleum and Natural Gas Extraction

95.4

64193

1.5

693208

10799

13646111

Bluffview Power Plant

NM

221112

Fossil Fuel Electric Power Generation

66.3

58864

1.1

625475

10626

14937311

Diamondback Compressor Station

0

2111

Oil and Gas Extraction

83.5

59649

1.4

606739

10172

1276

Harvest - Aztec Central Delivery Point

NM

213112

Support Activities for Oil and Gas Operations

74.6

55839

1.3

542345

9713

5050511

PacifiCorp- Hunter Power Plant

UT

221112

Fossil Fuel Electric Power Generation

10001.8

310435

32.2

2963323

9546

6281811

Bonanza

0

221112

Fossil Fuel Electric Power Generation

5721.7

326655

17.5

3031499

9280

 

Initial Discussion of Results – Mesa Verde National Park (MEVE) Class I area example

The RT, EWRT and WEP results are available for HYSPLIT back trajectories arriving at the IMPROVE site on the MIDs at 5 different heights above ground: 100 m, 200 m, 500 m, 1,000 m and All (combination of all four heights).  However, the products of the analysis are not that different for the different heights.  For example, the RT plots at MEVE shown in Figure 1 for the 100m, 1000m and All heights are very similar.  There are some differences in the relative rankings using the trajectories at different heights.  For example, the relative rankings of power plants with tall stacks is higher using the 1,000 m height than 100 m height back trajectories.  But examining all trajectory heights increases the number of plots to analyze by a factor of 5, so we recommend using just the All height trajectory as it will include the most data in the RT, EWRT, WEP and Rank_Point displays.