Impact of Reduced Nitrogen on Air Quality: Fine Scale

Simulation, Evaluation, and Sensitivity StudyKristen Olsen and Yang Zhang

Department of Marine, Earth, and Atmospheric Sciences, NC State University, Raleigh, NC

John WalkerDivision of Air Pollution Prevention and Control, US EPA, RTP, NC

Wayne RobargeDepartment of Soil Science, NC State University, Raleigh, NC

The 7th Annual CMAS Conference

Chapel Hill, NC, October 6-8, 2008

Motivation• Ammonia (NH3) emissions from

large number of animal feeding operations in southeast U.S., particularly in eastern North Carolina (NC)

• Impact of NH3

– An alkaline species with odors– Modulation of soil nutrient and

nitrogen cycles– Neutralization of acids in the air– Formation of fine particulate matter

(PM2.5)

Monthly Mean NH3 Emission

Objectives• Intercompare the performance of two air

quality models in simulating the fate and transport of reduced nitrogen (NHx = NH3 + NH4

+) at fine grid scales• Evaluate the sensitivity of air quality

predictions to a 50% reduction of emissions of agricultural livestock NH3 (AL-NH3)

• Examine model sensitivity to horizontal grid resolution (12-, 4-, and 1.33-km)

CMAQ – Community Multiscale Air Quality model, CAMx – Comprehensive Air Quality Model with extensions, MM5 – the 5th generation Mesoscale Model, FDDA – Four Dimensional Data Assimilation, VISTAS – Visibility Improvement State and Tribal Association of the Southeast, SMOKE – Sparse Matrix Operator Kernel Emission

Model Setup• Period: January and July 2002

• Horizontal/Vertical Resolutions: 4- and 1.33-km / 19 layers

• Air Quality Models: CMAQ v4.51, CAMx v4.42

• Meteorology Model: MM5 v3.7 with FDDA

• Emission Inventory: developed by VISTAS, processed through SMOKE v2.1

• IC/BC: VISTAS 12-km simulations

• Dataset for Evaluation: NCDENR North Carolina Department of Environment and Natural ResourcesNC CRONOS NC Climate Retrieval and Observations Network of the Southeast DatabaseCASTNET Clean Air Status and Trends Network NADP National Acid Deposition Program STN Speciation Trends NetworkSEARCH Southeastern Aerosol Research and Characterization IMPROVE Interagency Monitoring of Protected Visual Environments AIRS – AQS Aerometric Information Retrieval System – Air Quality Subsystem

Model TreatmentsCMAQ CAMx

Version 4.51 with ENVIRON’s revised SOA module

4.42

Gas-Phase Chemistry CB-IV CB-IV

Horizontal Advection PPM PPM

Vertical Advection Yamartino PPM

PM2.5 Size Representation 3 lognormal modes 2 sections

Aerosol Chemistry AE4 / ISORROPIA CF / ISORROPIA

Aqueous Chemistry RADM RADM

Dry Deposition M3Dry / RPM Wesely

Wet Deposition Aerosol and gas scavenging; Henry’s Law;

accumulation/coarse PM in cloud water, Aitken slowly absorbed

Aerosol and gas scavenging; Henry’s Law;

all PM in cloud water

CB-IV – Carbon Bond IV, PPM – Piecewise Parabolic Method, RADM – Regional Acid Deposition Model, CF – Coarse/Fine, RPM – Regional Particulate Model

Meteorology EvaluationJan.

Variable Network Data # MB NMB (%) Data # MB NMB (%)

T2(°C)

CASTNET 5157 -0.9 -11.0 7410 1.0 4.4

STN 60 0.6 8.9 134 -0.5 -1.7

SEARCH 1360 -3.0 -30.2 1393 -2.5 -8.8

RH2(%)

CASTNET 6857 4.4 6.3 6741 -5.7 -7.4

SEARCH 1455 10.7 15.3 1164 -3.4 -8.8

WSP10(m s-1)

CASTNET 4877 1.1 18.7 3251 1.1 31.0

SEARCH 1067 0.4 3.5 571 0.8 22.8

WDR10(°)

CASTNET 7098 12.1 6.0 7140 0.9 0.5

SEARCH 1455 0.3 6.0 1182 -6.5 -2.9

Prec (mm) NADP 72 -3.2 -11.0 84 45.6 151.3

Jul.

T2 – Temperature at 2-m, RH2 – Relative humidity at 2-m, WSP10 – Wind speed at 10-m, WDR10 – Wind direction at 10-m, Prec – Precipitation, MB – Mean Bias, NMB – Normalized Mean Bias

O3 and PM2.5 Normalized Mean Bias

CAMxCMAQ

Ja

n.

Ju

l.

-100-80-60-40-20

020406080

100

Max1-hrO3

Max8-hrO3 PM2.5 NH4 SO4 NO3 BC OC

AIRS CASTNET IMPROVE STN

-100-80-60-40-20

020406080

100120

Max 1-hr O3

Max 8-hr O3

PM2.5 NH4 SO4 NO3 BC OC

NMB,

%

-100-80-60-40-20

020406080

100120

Max 1-hr O3

Max 8-hr O3

PM2.5 NH4 SO4 NO3 BC OC

NMB,

%

-100-80-60-40-20

020406080

100120

Max 1-hr O3

Max 8-hr O3

PM2.5 NH4 SO4 NO3 BC OC

NMB,

%

-100-80-60-40-20

020406080

100120

Max 1-hr O3

Max 8-hr O3

PM2.5 NH4 SO4 NO3 BC OC

NMB,

%

PM2.5 Temporal Variation

Jul.Jan.

0

10

20

30

40

50

1/1/02 1/6/02 1/11/02 1/16/02 1/21/02 1/26/02 1/31/02

PM2.

5(μ

g m

-3)

Date (EST)

Jan. PM2.5, Raleigh obs CMAQ CAMx

0

20

40

60

80

1/1/02 1/6/02 1/11/02 1/16/02 1/21/02 1/26/02 1/31/02

PM2.

5(μ

g m

-3)

Date (EST)

Jan. PM2.5, Raleigh

0

20

40

60

80

7/1/02 7/6/02 7/11/02 7/16/02 7/21/02 7/26/02 7/31/02PM

2.5

(μg

m-3

)

Date (EDT)

Jul. PM2.5, Raleigh

0

10

20

30

40

50

7/1/02 7/6/02 7/11/02 7/16/02 7/21/02 7/26/02 7/31/02

PM2.

5(μ

g m

-3)

Date (EDT)

Jul. PM2.5, Kinston obs CMAQ CAMx

0

10

20

30

40

50

1/1/02 1/6/02 1/11/02 1/16/02 1/21/02 1/26/02 1/31/02

PM2.

5(μ

g m

-3)

Date (EST)

Jan. PM2.5, Kinston obs CMAQ CAMx

0

20

40

60

80

100

1/1/02 1/6/02 1/11/02 1/16/02 1/21/02 1/26/02 1/31/02

PM2.

5(μ

g m

-3)

Date (EST)

Jan. PM2.5, Atlanta

0

20

40

60

80

100

7/1/02 7/6/02 7/11/02 7/16/02 7/21/02 7/26/02 7/31/02

PM2.

5(μ

g m

-3)

Date (EDT)

Jul. PM2.5, Atlanta

Raleigh, NC

Atlanta, GA

Kinston, NC

% Conversion of NH3 to NH4+

(NH4+/NHx)

Jan

.Ju

l.

CAMxCMAQ

Impacts of NH3 Control in July 2002Base Case - Monthly Mean Impact of NH3 Control – Abs. Difference

AdjGR = ([NO3-]+[NH3]) / ([NO3

-]+[HNO3])

PM2.5

AdjGR

NO3-

Sensitivity to Grid Resolution(CMAQ, July)

CMAQ - July - STN

-100-80-60-40-20

020406080

100

PM2.5 NH4 SO4 NO3 TC

NMB,

%

CMAQ - July

-30-20-10

01020

AIRS CASTNET AIRS CASTNETMax 1-hr O3 Max 8-hr O3

NMB,

%

CMAQ - July - NADP

-90-60-30

0306090

120150180210

Precip WD_NH4 WD_SO4 WD_NO3

NMB,

%

CMAQ - July - CASTNET

-100-80-60-40-20

020406080

100

NH4 SO4 NO3

NMB,

%

-30-20-10

01020

AIRS CASTNET AIRS CASTNET

12-km 4-km 1.33-km

NH4+/NHx Sensitivity to Grid

Resolution (CMAQ, July)

12-km 4-km

1.33-km

Summary• MM5 performance is reasonably good, except for precipitation in July.

CMAQ and CAMx perform similarly for O3 but differently for PM2.5 and composition, with worse performance for NO3

- and OC by CMAQ in both months, others better by CMAQ in Jan. but by CAMx in Jul.

• Compared to CMAQ, CAMx gives similar conversion rates of NH3 to NH4

+ in Jan., but higher rates in Jul., possibly due to differences in vertical mixing, deposition, and aerosol treatments.

• 50% AL-NH3 emission reduction in Jul. leads to lower PM2.5 by up to 8% via decreasing NH4NO3 and an increased role of transport via increasing ratios of NH4

+/NHx near the source.• The use of 4- and 1.33-km resolutions without adequate NH3 source

treatments does not improve model performance in Jul.

Acknowledgments• This project is supported by National Research Initiative

Competitive Grant no. 2008-35112-18758 from the USDA Cooperative State Research, Education, and Extension Service Air Quality Program

• Pat Brewer, Mike Abraczinskas, George Bridgers, Bebhinn Do, Chris Misenis, Hoke Kimball, and Wayne Cornelius, NCDENR

• Don Olerud, Baron Advanced Meteorological Systems • Dennis McNally and Cyndi Loomis, Alpinephysics, Inc. • Ryan Boyles, NC State Climate Office • Alice Gilliland, Steve Howard, and Shao-Cai Yu, U.S. EPA • Shiang-Yuh Wu, Clark County Department of Air Quality and

Environmental Management

Extras

CM

AQ

CA

Mx

Wet Deposition of NH4+/NHx

Jul.Jan.

Impacts of NH3 Control in July 2002:AdjGR

Base Case Reduction of AL-NH3

AdjGR = ([NO3-]+[NH3])

([NO3-]+[HNO3])

Impacts of NH3 Control in July 2002:

NH4+/NHxBase Case Reduction of AL-NH3

% Difference

Impacts of NH3 Control in July 2002

Impacts of NH3 Control in July 2002

[NH3]emis, 50% AL-NH3 / [NH3]emis, base

Sensitivity to Grid Resolution (CMAQ, July)

Variable NetworkData

#MeanObs

Mean Sim NMB (%)

12-km 4-km 12-km 4-km

PM2.5

IMPROVE 55 15.8 7.9 6.7 -50.1 -57.8

STN 127 19.3 10.3 9.7 -46.1 -49.6

NH4+

CASTNET 40 2.3 1.1 1.1 -50.3 -52.4

IMPROVE 9 1.7 0.9 0.7 -48.4 -57.3

STN 135 2.0 1.3 1.2 -37.3 -41.2

SO42-

CASTNET 40 8.3 7.3 6.3 -12.3 -23.9

IMPROVE 56 7.1 5.4 4.3 -23.6 -39.1

STN 135 7.2 5.9 4.7 -18.0 -34.3

NO3-

CASTNET 40 0.2 0.0 0.1 -81.4 -73.4

IMPROVE 56 0.2 0.1 0.1 -80.2 -61.8

STN 135 0.7 0.1 0.1 -89.9 -86.9

BCIMPROVE 43 0.3 0.2 0.2 -42.5 -46.6

STN 134 0.4 0.5 0.5 20.8 37.6

OCIMPROVE 43 2.3 0.7 0.6 -70.3 -72.5

STN 134 4.8 1.3 1.4 -74.1 -71.6

Variable NetworkData

#MeanObs

Mean Sim NMB (%)

12-km 4-km 12-km 4-km

O3

(1-hr max)

AIRS 3216 71 65 62 -8.6 -12.6

CASTNET 300 66 61 60 -7.0 -8.8

O3

(8-hr max)

AIRS 3215 63 61 56 -3.4 -10.1

CASTNET 300 58 58 56 -1.0 -5.0

WD_NH4 NADP 69 0.3 0.2 0.2 -45.0 -23.2

WD_SO4 NADP 69 2.2 1.7 3.0 -18.9 38.3

WD_NO3 NADP 69 1.6 0.5 0.9 -69.6 -43.5

Prec NADP 84 30.1 63.8 75.7 111.9 151.3

Sensitivity to Grid Resolution (CMAQ, July)

12-km 4-km

-100-80-60-40-20

0204060

Max 1-hr O3

Max 8-hr O3

PM2.5 NH4 SO4 NO3 BC OC

NM

B, %

-100-80-60-40-20

0204060

Max 1-hr O3

Max 8-hr O3

PM2.5 NH4 SO4 NO3 BC OC

NM

B, %

WD_NH4 – Wet deposition of NH4+,

WD_SO4 – Wet deposition of SO42-,

WD_NO3 – Wet deposition of NO3-

PM2.5 Sensitivity to Grid Resolution(CMAQ, July)12-km 4-km

1.33-km