COMPARATIVE MODEL PERFORMANCE EVALUATION OF CMAQ-VISTAS, CMAQ-MADRID, AND CMAQ-MADRID-APT FOR A NITROGEN DEPOSITION ASSESSMENT OF THE ESCAMBIA BAY, FLORIDA.
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COMPARATIVE MODEL PERFORMANCE EVALUATION OF CMAQ-VISTAS, CMAQ-MADRID, AND CMAQ-
MADRID-APT FOR A NITROGEN DEPOSITION ASSESSMENT OF THE
ESCAMBIA BAY, FLORIDA WATERSHED
6th Annual CMAS ConferenceChapel Hill, NC
1-3 October 2007
Presented by Jay Haney ICF International, San Rafael, CA
Co-Authors: Sharon Douglas Tom Myers
Justin Walters John Jansen
Krish Vijayaraghavan AER
Project sponsored by Southern Co.
ICF
Southern Company
Background/Objectives
Atmospheric deposition of nitrogen is a source of contamination in Escambia Watershed
Air quality modeling performed to estimate change in nitrogen deposition in watershed due to controls at a local EGU as part of larger combined air/water quality modeling analysis
Objective for this part of study: Assess the ability of air quality models to replicate observed gaseous and particulate concentrations and wet and dry deposition
Air Quality Models Used:Based on CMAQ 4.5.1
CMAQ-VISTAS: CB-IV, AERO4, modified SOA by VISTAS
CMAQ-MADRID: Sectional representation of particle size distribution as opposed to modal for CMAQ
CMAQ-MADRID-APT: “Advanced plume treatment” based on SCIPUFF with CHEMistry – SCICHEM
Air Quality Modeling Databases
Meteorological inputs: VISTAS 2002 inputs from RPO modeling analysis
Emissions: CMAQ-VISTAS: Base_G1 MADRID & APT: Base_F
Domain: 12-km ALGA, subset of VISTAS domain centered on Alabama & Georgia
Annual simulations for 2002
CMAQ ALGA Subdomain/Escambia Watershed
Oak GroveOLF
Gulfport Pensacola
Centreville
N. BirminghamJefferson St.
Yorkville
Oak GroveOLF
Gulfport Pensacola
Centreville
N. BirminghamJefferson St.
Yorkville
CMAQ ALGA Subdomain
Escambia Watershed
Plant Crist
Air Quality Data Used in Evaluation
SEARCH: Hourly gaseous and 3-day speciated PM2.5 concentrations
IMPROVE: 3-day speciated PM2.5 concentrations
CASTNET: Weekly particulate concentrations and derived dry deposition based on concentration/ambient conditions
NADP: Weekly particulate concentrations and wet deposition
Model Performance Measures
Mean bias, normalized bias, fractional bias, mean error, normalized gross error, and fractional gross error
Paired for appropriate time interval
Statistics calculated using daily averages, except for CASTNET and NADP weekly measurements
Statistics calculated for all sites/species in ALGA domain with focus on sites near Escambia watershed
Location of SEARCH and CASTNET Sites in CMAQ
Subdomain
SEARCH Sites CASTNET Sites
Coffeeville
Sand Mountain
Georgia Station
Sumatra
Coffeeville
Sand Mountain
Georgia Station
Sumatra
Oak GroveOLF
Gulfport Pensacola
Centreville
N. BirminghamJefferson St.
Yorkville
Oak GroveOLF
Gulfport Pensacola
Centreville
N. BirminghamJefferson St.
Yorkville
Location of IMPROVE and NADP Sites in CMAQ Subdomain
IMPROVE Sites NADP Sites
St. Marks
Sipsey
Chassahowitzka
Cohutta
Okefenokee
CapeRomain
Linville Gorge
Shining Rock
Great Smoky MtnCadiz
Mammoth Cave
Breton
St. Marks
Sipsey
Chassahowitzka
Cohutta
Okefenokee
CapeRomain
Linville Gorge
Shining Rock
Great Smoky MtnCadiz
Mammoth Cave
Breton
Mobile Co.
Baldwin Co.
Quincy
SumatraMobile Co.
Baldwin Co.
Quincy
Sumatra
Results for Gaseous Species: SO2 for SEARCH Sites
Mean Observed & Simulated SO2
0
2
4
6
8
PNS OLF GFP OAK CTR BHM YRK JST
ppb
OBS
CMAQ
MADRID
APT
Results for Gaseous Species: SO2 for SEARCH Sites
Fractional Bias & Error: SO2
-100-80-60-40-20
020406080
100
PNS OLF GFP OAK CTR BHM YRK JST
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Results for Gaseous Species: HNO3 for SEARCH Sites
Mean Observed & Simulated HNO3
0.0
0.5
1.0
1.5
2.0
PNS OLF GFP OAK CTR BHM YRK JST
ppb
OBS
CMAQ
MADRID
APT
Results for Gaseous Species: HNO3 for SEARCH Sites
Fractional Bias & Error: HNO3
-200-160-120
-80-40
0
4080
120160200
PNS OLF GFP OAK CTR BHM YRK JST
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Gaseous Species Summary
For SO2, all models slightly underestimate concs nearby (evidence of differences between MADRID and APT in Atlanta area)
For HNO3, all models consistently overestimate at nearby sites
For NO2, all models do well and for NO, all models underestimate, but these are typically not major contributors to nitrogen deposition
Results for Particulate Species: NO3 for SEARCH Sites
Mean Observed & Simulated NO3
0.0
0.4
0.8
1.2
1.6
2.0
PNS OLF GFP OAK CTR BHM YRK JST
ugm
-3
OBS
CMAQ
MADRID
APT
Results for Particulate Species: NO3 for SEARCH Sites
Fractional Bias & Error: NO3
-200-160-120
-80-40
0
4080
120160200
PNS OLF GFP OAK CTR BHM YRK JST
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Results for Particulate Species: NH4 for SEARCH Sites
Mean Observed & Simulated NH4
0
1
2
3
4
PNS OLF GFP OAK CTR BHM YRK JST
ugm
-3
OBS
CMAQ
MADRID
APT
Results for Particulate Species: NH4 for SEARCH Sites
Fractional Bias & Error: NH4
-100-80-60-40-20
0
20406080
100
PNS OLF GFP OAK CTR BHM YRK JST
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Particulate Species Summary
For nitrate, CMAQ better simulates mean conc. but fractional bias and error are lower for MADRID and APT at nearby sites
For ammonium, all models show consistent underestimation at nearby sites, and overestimation at BHM and ATL
Results for Dry Deposition: NO3 for CASTNET Sites
Fractional Bias & Error: NO3 Dry Dep.
-200-160-120
-80-40
04080
120160200
Coffeeville, MS Sand Mtn, AL Georgia Station, GA Sumatra, FL
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Results for Dry Deposition: NH4 for CASTNET Sites
Fractional Bias & Error: NH4 Dry Dep.
-200-160
-120-80-40
0
4080
120
160200
Coffeeville, MS Sand Mtn, AL Georgia Station, GA Sumatra, FL
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Results for Dry Deposition: HNO3 for CASTNET Sites
Fractional Bias & Error: HNO3 Dry Dep.
-200-160-120-80-40
04080
120160200
Coff eeville, MS Sand Mtn, AL Georgia
Station, GA
Sumatra, FL
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Results for Wet Deposition: NO3 for NADP Sites
Fractional Bias & Error: NO3 Wet Deposition
-100-80-60
-40-20
02040
6080
100
Baldwin Co., AL Mobile Co., AL Quincy, FL Sumatra, FL
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Results for Wet Deposition: NH4 for NADP Sites
Fractional Bias & Error: NH4 Wet Deposition
-100-80
-60-40-20
0
204060
80100
Baldwin Co., AL Mobile Co., AL Quincy, FL Sumatra, FL
Perc
ent (
%)
MFB-CMAQ
MFE-CMAQ
MFB-MADRID
MFE-MADRID
MFB-APT
MFE-APT
Dry Deposition Summary
For nitrate and ammonium dry deposition, all models show consistent gross underestimation
For HNO3 dry deposition, all models show consistent overestimation, with MADRID and APT showing more overestimation than CMAQ
With HNO3 higher than NO3 (simulated and observed), net result is that all models overestimate dry deposition of nitrates
Dry deposition estimates complicated by potential differences in meteorology used for data vs. model
Wet Deposition Summary
Models do better in simulating wet deposition and are consistent in underestimating wet deposition at nearby sites
Larger differences seen between models: effects of plume-in-grid treatment for APT?
Summary and Key Findings
Results are mixed: none of the models stand out as better performing
Greatest contributor to nitrogen deposition is dry deposition of HNO3, followed by wet deposition of nitrate (all forms)
Simulated net wet deposition of nitrogen is lower than observed while simulated net dry deposition is higher, so total loading of nitrogen in domain may be adequately simulated
Summary and Key Findings
Dry deposition monitoring not available in Escambia watershed, so performance may not be representative
Deposition output from all three models was used in water quality modeling assessment
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