Impact of Reduced Nitrogen on Air Quality: Fine Scale Simulation, Evaluation, and Sensitivity Study

1
Impact of Reduced Nitrogen on Air Quality Fine
Scale Simulation, Evaluation, and Sensitivity
Study

• Kristen Olsen and Yang Zhang
• Department of Marine, Earth, and Atmospheric
  Sciences, NC State University, Raleigh, NC
• John Walker
• Division of Air Pollution Prevention and Control,
  US EPA, RTP, NC
• Wayne Robarge
• Department of Soil Science, NC State University,
  Raleigh, NC
• The 7th Annual CMAS Conference
• Chapel Hill, NC, October 6-8, 2008

2
Motivation
Monthly Mean NH3 Emission

• 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)

3
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)

4
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

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
5
Model Treatments
CMAQ CAMx
Version 4.51 with ENVIRONs 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 Henrys Law accumulation/coarse PM in cloud water, Aitken slowly absorbed Aerosol and gas scavenging Henrys 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
6
Meteorology Evaluation

• Jan.

• Jul.

Variable Network Data MB NMB () Data MB NMB ()
T2 (C) CASTNET 5157 -0.9 -11.0 7410 1.0 4.4
T2 (C) STN 60 0.6 8.9 134 -0.5 -1.7
T2 (C) SEARCH 1360 -3.0 -30.2 1393 -2.5 -8.8
RH2 () CASTNET 6857 4.4 6.3 6741 -5.7 -7.4
RH2 () 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
WSP10 (m s-1) SEARCH 1067 0.4 3.5 571 0.8 22.8
WDR10 () CASTNET 7098 12.1 6.0 7140 0.9 0.5
WDR10 () SEARCH 1455 0.3 6.0 1182 -6.5 -2.9
Prec (mm) NADP 72 -3.2 -11.0 84 45.6 151.3
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
7
O3 and PM2.5 Normalized Mean Bias
CAMx
CMAQ
Jan.
Jul.
8
PM2.5 Temporal Variation
Jul.
Jan.
Atlanta, GA
Raleigh, NC
Kinston, NC
9
Conversion of NH3 to NH4 (NH4/NHx)
CAMx
CMAQ
Jan.
Jul.
10
Impacts of NH3 Control in July 2002
Base Case - Monthly Mean
Impact of NH3 Control Abs. Difference
PM2.5
AdjGR
AdjGR (NO3-NH3) / (NO3-HNO3)


NO3-
11
Sensitivity to Grid Resolution(CMAQ, July)
12
NH4/NHx Sensitivity to Grid Resolution (CMAQ,
July)
12-km
4-km
1.33-km
13
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.

14
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

15
Extras
16
Wet Deposition of NH4/NHx
Jul.
Jan.
CMAQ
CAMx
17
Impacts of NH3 Control in July 2002AdjGR
Base Case
Reduction of AL-NH3
AdjGR (NO3-NH3)
(NO3-HNO3)
18
Impacts of NH3 Control in July 2002NH4/NHx
Base Case
Reduction of AL-NH3
Difference
19
Impacts of NH3 Control in July 2002
20
Impacts of NH3 Control in July 2002
21
NH3emis, 50 AL-NH3 / NH3emis, base
22
Sensitivity to Grid Resolution (CMAQ, July)
Variable Network Data Mean Obs Mean Sim Mean Sim NMB () NMB ()
Variable Network Data Mean Obs 12-km 4-km 12-km 4-km
PM2.5 IMPROVE 55 15.8 7.9 6.7 -50.1 -57.8
PM2.5 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
NH4 IMPROVE 9 1.7 0.9 0.7 -48.4 -57.3
NH4 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
SO42- IMPROVE 56 7.1 5.4 4.3 -23.6 -39.1
SO42- 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
NO3- IMPROVE 56 0.2 0.1 0.1 -80.2 -61.8
NO3- STN 135 0.7 0.1 0.1 -89.9 -86.9
BC IMPROVE 43 0.3 0.2 0.2 -42.5 -46.6
BC STN 134 0.4 0.5 0.5 20.8 37.6
OC IMPROVE 43 2.3 0.7 0.6 -70.3 -72.5
OC STN 134 4.8 1.3 1.4 -74.1 -71.6
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Sensitivity to Grid Resolution (CMAQ, July)
Variable Network Data Mean Obs Mean Sim Mean Sim NMB () NMB ()
Variable Network Data Mean Obs 12-km 4-km 12-km 4-km
O3 (1-hr max) AIRS 3216 71 65 62 -8.6 -12.6
O3 (1-hr max) CASTNET 300 66 61 60 -7.0 -8.8
O3 (8-hr max) AIRS 3215 63 61 56 -3.4 -10.1
O3 (8-hr max) 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
WD_NH4 Wet deposition of NH4, WD_SO4 Wet
deposition of SO42-, WD_NO3 Wet deposition of
NO3-
12-km
4-km
24
PM2.5 Sensitivity to Grid Resolution(CMAQ, July)
12-km
4-km
1.33-km