Transcript Slide 1

Use of National PM2.5 and
Speciation Network Measurements
for Model Evaluation
For presentation at
PM Model Performance Workshop
February 10-11, 2004: Research Triangle Park, NC
Neil Frank
OAQPS/USEPA
Scope
• Networks
–
–
–
–
FRM
EPA Urban Speciation (aka STN)
IMPROVE
CASTNET
• Measurements
– PM2.5 mass
– Major Chemical Components
– Sulfur and Nitrogen Species
• Data interpretation related to Model Evaluation
National Speciation Networks
IMPROVE
EPA spec.
CASTNET
filters + HNO3 denuder
filters + HNO3 denuder
Simple Filter pack
Main Purpose
Visibility
PM NAAQS
Deposition
Time avg
24-hr
24-hr
weekly
Particle size
PM2.5
PM2.5
>=PM2.5
Frequency
1 in 3 days
1 in 3 / 1 in 6
complete
No. Sites
110 + 54=164
54 + 186 = 240
87  ?
Sampler types
1
6
1
Reporting
Local conditions
Local conditions
STP (&local)
Sulfates
Ambient
Ambient
Ambient
<=ambient?
<= ambient
Ambient
<=ambient
Ammonium
pNO3
Ambient
HNO3
-
-
>=ambient
TNO3
-
-
~ambient
OC/EC
DRI method (TOR)
EPA/NIOSH (TOT)
-
Crustal
Estimated from Al, Si,
Ca, Fe, Ti
same
-
CASTNET Network
Dense in Ohio Valley and Eastern US
8 Supplementary PM2.5
Speciation Sites (1993-2002)
PM2.5 speciation sites
(became IMPROVE in 2001 )
FilterPacks
IMPROVE Network, 2002
98 Sites with “complete” data, Mar 01-Feb 02
Sulfate Variation in Rural Areas
Comparison of CASTNET and IMPROVE Measurements in 2001
CASTNET
2001
IMPROVE
March 01 – Feb 02
Sulfate
0 - 0.4
0.4 - 0.5
0.5 - 0.7
0.7 - 1
1 - 1.3
1.3 - 1.7
1.7 - 2.2
2.2 - 3.5
3.5 - 4.2
4.2 - 5
Concentrations, STP
Nitrate Variation in Rural Areas
March 01 – Feb 02
CASTNET
CASTNET
2001
2001
IMPROVE
March 01 – Feb 02
Nitrate
0 - 0.1
0.1 - 0.2
0.2 - 0.3
0.3 - 0.4
0.4 - 0.5
0.5 - 0.6
0.6 - 0.7
0.7 - 1
1 - 1.5
1.5 - 2.5
Concentrations, STP
Better resolution will come
from new ( 2002-2003) data
Gradient is overstated
HNO3 exhibit different spatial pattern
TNO3 also shows a MidWest to East gradient
NO3
HNO3
Concentrations, STP
2.7 + 2.1 = 4.8 ug/m3
0.8 + 2.0 = 2.8 ug/m3
NO3 HNO3
NO3
TNO3
HNO3
TNO3
CASTNET Comparisons
Sulfates and Nitrates
Western and Eastern Sites
Ames RB, Malm WC (2001) Comparison of sulfate and
nitrate particle mass concentrations measured by IMPROVE and the CDN.
ATMOSPHERIC ENVIRONMENT 35 (5): 905-916.
Sulfate: Comparison of 4-week mean IMPROVE and CASTNET
Great Agreement for Sulfates (after adjustment to LTP)
Particle Nitrate: Comparison of 4-week mean IMPROVE and CASTNET
Relative Bias for particle Nitrates
/DC
20
Nitrate difference as a % of CM
D NO 3 / CM (%) and Temperature (
o
C)
18
BBE
Temperature
16
PIN
14
CHA
SEK
CAN
12
YOS
10
MOR
8
ROM
GLR
MEV
GRB
GRC
LAV
PND
YEL
SEK
6
PIN
4
BBE
MEV
YOS LAV
GRB
GRC
ROM
PND CAN
YEL
MOR
2
0
GLR
CHA
-2
-50
0
50
100
150
DNO3- (%)
From: Rodger B. Ames and William C. Malm Comparison of sulfate and nitrate particle mass concentrations measured by IMPROVE and the CDN
CASTNET filterpak and PM2.5 nitrates in the Eastern US:
better agreement in Midwest and during later years
Hypothesis: Better NH4NO3 retention on teflon with free ambient NH3
4.0
9.0
8.0
IL
7.0
6.0
5.0
4.0
3.5
BVL filterpak
2.5
amm_nitrate (PM2.5)
2.0
1.5
2.0
1.0
1.0
4.5
5.0
4.0
4.5
01-2
00-4
00-2
99-4
99-2
98-4
98-2
97-4
97-2
96-4
96-2
95-5
95-2
94-4
93-4
-2
-3
01
-4
00
-1
99
-3
-2
99
98
-4
97
-1
96
-2
96
-3
95
94
0.0
94-2
0.5
0.0
-4
QAK filter pak
ammonium_nitrate
IMPROVE
3.0
93
OH
3.0
4.0
3.5
KY
3.0
NW PA
3.5
3.0
2.5
CDZ filter pak
ammonium_nitrate
2.0
MKG filter pak
ammonium_nitrate
2.5
2.0
1.5
1.5
1.0
1.0
0.5
0.5
-2
01
-4
00
-2
-4
00
99
-2
99
-4
-4
-2
98
98
97
-4
-2
97
-2
96
-2
-5
96
95
-2
-4
95
94
94
93
01-2
00-3
99-4
99-1
98-2
97-3
96-4
96-1
95-2
94-3
93-4
-4
0.0
0.0
Less NO3 Agreement between CASTNET filter pack and PM2.5 nitrate
as the sites move to the East
Hypothesis: Poorer NH4NO3 retention on teflon in NH3 limited environments
3.5
3.0
2.5
2.0
CTH filter pak
ammonium_nitrate
1.5
1.0
0.5
-2
-4
01
-2
00
-4
00
-2
99
-4
99
-2
98
-4
98
-2
97
-4
97
-2
96
-5
96
-2
95
-4
95
-2
94
94
93
-4
0.0
6.0
5.0
4.0
ARE filter pak
ammonium_nitrate
3.0
Note: different than pNO3 loss with
FRM measurements for PM2.5
2.0
1.0
01-2
00-3
99-4
99-1
98-2
97-3
96-4
96-1
95-2
94-3
93-4
0.0
Quarterly Average NO3: CASTNet vs PM2.5 Speciation
Good agreement in rural IL…. Relative Bias at Western NYS
PM2.5 Speciation
Bondville, IL
CTH, NY
10
3
1:1
8
3:2
2
6
4
1
2
0
0
0
2
4
6
8
10
0
CASTNET NO3, ug/m3
1
2
3
Routine Estimates of Ambient Carbon
More Uncertain than other measurements
• Carbon
– Inter-network differences in Measured C
• IMPROVE and STN use different thermo-optical techniques
to measure carbon
• Many studies suggest that IMPROVE EC~=2x STN EC
• More recent results reveal more agreement
– Total Carbonaceous Mass is estimated as
• TCM = k* OC +EC
– Where k can be 1.2 to > 2.5 (+/- 30% regional uncertainty)
– IMPROVE uses 1.4
• OC is blank corrected for artifacts using network-wide
estimates
……but still sufficiently robust for model evaluation
Blank corrections vary by Sampler
Can Represent Substantial Portion of Measured Values
* National Air Quality and Emission Trends Report 2003 Special Studies Edition
http://www.epa.gov/oar/aqtrnd03/
IMPROVE
MASS
R&P
MetOne (SASS): 9.6 m3
Anderson (RASS): 10.4 m3
R&P: 14.4 m3
URG (MASS): 24 m3
IMPROVE: 32.8 m3
OC
blank,
ug/m3
RAAS
–
–
–
–
–
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Preliminary OC Blank Corrections
Used by Rao, Frank, et al*
SASS
• Derived from network
average quartz filter field
blanks to adjust annual
averages
• Varies by 24-hr sampler
volume
Newest Blank Corrections Are Slightly Different
Values used by
Rao et al.
0.56
0.93
1.28
1.4
Newest Blank Corrections
OC now corrected with Total Carbon value
Reference: Analysis of Speciation
Network Carbon Blank Data
DRAFT REPORT, Flanagan et al
RTI International August 30, 2002
OC correction, ug/m3
1.8
1.6
1.4
1.2
1
For this analysis
Newest estimates
0.8
0.6
0.4
0.2
0
SASS
RAAS
R&P
MASS
Evaluation of OC blank correction for 12-month averages
using measured OC vs PM2.5 mass
OC w Blank
Adjustment
smaller intercept
OC
wo Blank has
adjustment
OC concentration, ug/m3
10
y =y0.26x
+ 0.92
= 0.23x
+ 0.12
8
6
4
2
0
0
5
10
15
20
10
15
20
PM2.5 Mass Concentration, ug/m3
25
25
TCM Variation in Rural Areas
March 01 – Feb 02
Total Carbon Mass
0.7 - 1
1 - 1.3
1.3 - 1.5
1.5 - 1.8
1.8 - 2
2 - 2.6
2.6 - 3.3
3.3 - 4.2
4.2 - 5.4
5.4 - 7.0
TCM=1.8*OC+EC
Based on TCM= OC*1.8+EC
13 Selected Urban Sites are Paired with Rural
Sites for “Urban PM2.5 Excess” Calculations
Missoula
Cleveland
Fresno
SLC
Indy
S.L.
Tulsa
Birmingham
13 urban STN sites
16 rural IMPROVE sites
Bronx
Baltimore
Richmond
Charlotte
Atlanta
Urban PM2.5 is Higher than Nearby Rural Concentrations
Gravimetric M ass
30
Top:
Urban
Bott om:
R egional C ontribution
Top: U rban
Increm ent
Bottom:
Rural
20
15
10
Urban Increment
Regional Con tribution
12-month average PM2.5 mass from speciation samplers
- PM2.5 STN mass is affected by high filter blanks prior to ~August 2001
Bronx/BRIG
Baltimore/DO SO
Richmond/JARI
Charlotte/LI GO
Cleveland/MKG O
Atlanta/2 Sites
Indy/LIVO
Birmingham/SIP
St.Louis/3 S ites
SLC/G RBA
Missoula/MO NT
0
Tulsa/WIMO
5
Fresno/PINN
ug/m3
25
Estimated Annual “Urban Excess” for Baltimore, MD
Dolly Sods, WV
“Urban
Baltimore
Excess”
MD
Rural
Rural
Concentrations
Concentrations
= Urban
– Rural
concentrations
Adjusted
Superimposed
for
Elevation
onsite
differential
Urban
Rural IMPROVE site
STN urban
(background)
9
9
6
3
Top bars are urban
concentrations
6
Bottom bars are nearby
rural concentration
3
0
0
0
Sulfate
Ammonium
Nitrate
TCM1.8
Crustal
Sulfate Ammonium
Ammonium
Nitrate
TCM1.8
TCM1.8
Crustal
Crustal
Crustal
Ambient Urban Excess Concentrations
for 13 example areas
Sulfate:
0.0 0.4
0.9
Missoula
Ammonium:
0.0 0.9
1.9
Nitrate:
Bronx
Cleveland
SLC
Baltimore
Indy
Fresno
0.4 3.5
St Louis
6.5
Richmond
TCM (k=1.8):
Tulsa
Charlotte
(k=1.4)
Birmingham
Atlanta
2.9 8.1 13.2
Range of TCM based
on “k”= 1.4 to 1.8
Crustal:
0.0 0.4
0.8
“Urban Excess”
= urban concentration – regional background
urban excess, ug/m3
25
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
20
15
10
5
Gravimetric mass
Chemical Components
Bronx/BRIG
Baltimore/DOSO
Richmond/JARI
Charlotte/LIGO
Cleveland/MKGO
Atlanta/2 Sites
Indy/LIVO
Birmingham/SIPS
St.Louis/3 Sites
Tulsa/WIMO
SLC/GRBA
Missoula/MONT
Fresno/PINN
0
excess carbon, % of PM2.5
Carbon is > 50-80% of the Urban Excess
%TCM1.4 of total
Note: GM excess is higher in part, because of bias in STN mass thru June 2001, and because GM contains water.
With straight inter-network comparison,
We see a large OC increment,
but…. OC urban increment is potentially over stated
**(OCM k=1.4)
Regional Contribution Urban Increment
Bronx/BRIG
Baltimore/DOSO
Richmond/JARI
Charlotte/LIGO
Cleveland/MKGO
Atlanta/2 Sites
Indy/LIVO
Birmingham/SIPS
St.Louis/3 Sites
Tulsa/WIMO
SLC/GRBA
Missoula/MONT
Fresno/PINN
12
10
8
6
4
2
0
Note: Comparisons based on different thermo-optical techniques
* “k” for OCM in rural areas is likely > 1.4, further reducing urban increment as presented
With straight inter-network comparison,
we don’t always see a large urban increment for EC
Assuming IMPROVE EC > STN EC, urban increment is potentially understated
Regional Contribution
EC Urban Increment
Note: Comparisons based on different thermo-optical techniques
Bronx/BRIG
Baltimore/DOSO
Richmond/JARI
Charlotte/LIGO
Cleveland/MKGO
Atlanta/2 Sites
Indy/LIVO
Birmingham/SIPS
St.Louis/3 Sites
Tulsa/WIMO
SLC/GRBA
Missoula/MONT
Fresno/PINN
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
By accounting for potential relative bias in reported EC The
Urban EC Increment Can Be Bounded
Assuming IMPROVE EC > STN EC > ½ IMPROVE EC
Regional (lower est)
Regional or add'l urban incr.
EC Urban Increment
Note: Comparisons based on different thermo-optical techniques
Bronx/BRIG
Baltimore/DOSO
Richmond/JARI
Charlotte/LIGO
Cleveland/MKGO
Atlanta/2 Sites
Indy/LIVO
Birmingham/SIPS
St.Louis/3 Sites
Tulsa/WIMO
SLC/GRBA
Fresno/PINN
Missoula/MONT
Upper Estimate
EC urban excess
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Other Issues
• Data reporting conventions
– STP vs LTP
– Using high elevation site data to represent
regional concentrations
• Inter-annual variability
• PM2.5 mass vs. Component species
Estimated Annual “Urban Excess” for Baltimore, MD
Elevation adjustment is a small technical
correction to the “Urban Excess” calculation
Concentration, ug/m3
9
Urban excess
after
elevation
adjustment
6
3
0
Sulfate Ammonium
Nitrate
TCM1.8
Crustal
Concentration at 1158m (Dolly Sods) is 12% lower
than a “sea level” estimate
Focus on Dolly Sods, WV Average Sulfate
March 01 – Feb 02
Sulfate
0 - 0.4
0.4 - 0.5
0.5 - 0.7
0.7 - 1
1 - 1.3
1.3 - 1.7
1.7 - 2.2
2.2 - 3.5
3.5 - 4.2
4.2 - 5
Elevation adjustment increases average DOSO sulfate to 4.8 ug/m3
Local Condition Concentrations < High Elevation STP Concentrations
http://capita.wustl.edu/CAPITA/CapitaReports/LocalPM10/LocalP10.HTML#combpandt
Local Condition Concentrations > Cold Area STP Concentrations
http://capita.wustl.edu/CAPITA/CapitaReports/LocalPM10/LocalP10.HTML#combpandt
Local Condition Concentrations vs STP Concentrations
http://capita.wustl.edu/CAPITA/CapitaReports/LocalPM10/LocalP10.HTML#combpandt
CASTNET sites
Large Inter-annual Variability in NO3, 2000-02
Trend sites
Northern
MidWest/NE
Southeast
Q1 Average Nitrate
Annual Average Nitrates
5.0
2.5
6 Northern
2.0
16 MWest/NE
1.5
15 Southeast
4.5
4.0
3.5
3.0
2.5
1.0
2.0
1.5
0.5
1.0
0.5
0.0
19
97
19
98
19
99
20
00
20
01
20
02
19
95
0.0
1995
Expressed as Ammonium Nitrates, 1.29*NO3
1997
1998
1999
2000
2001
2002
Use of PM2.5 Measurements
PM2.5 FRM Monitoring Sites
•
•
•
FRM Mass not = Ambient PM2.5
Ambient PM2.5
= [Sulfates] + [Nitrates] + [Carbon Mass] +[Crustal] +[Other]
Approximation used by IMPROVE program:
PM2.5
= [SULFATE] + [NITRATES] + [OCM] + [LAC] + [fine soil]
• NH42SO4 and NH4NO3 estimated from 3*S and NO3
• OCM=1.4*OC
• Fine soil estimated as 2.2[Al]+2.49[Si]+1.63[Ca]+2.42[Fe]+1.94[Ti]
• FRM mass
– does not retain all particle nitrates
– Includes particle bound water and “other” (e.g. passive PM2.5)
– OCM probably different than 1.4*OC
= [Ammoniated Sulfate Mass] + [Retained Nitrate Mass] + [Retained
Carbonaceous Mass] + [Metallic Metal Oxides] + [Other
Components]
Summary
• Many issues associated with Air Quality
Measurement
• Uncertainties are relatively small for Model
Evaluation Purposes