use of national pm2.5 and speciation network measurements for model evaluation for presentation at...

Use of National PM2.5 and Speciation Network Measurements

for Model EvaluationFor presentation at

PM Model Performance Workshop February 10-11, 2004: Research Triangle Park, NC

Neil FrankOAQPS/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 filters + HNO3 denuder

EPA spec. filters + HNO3 denuder

CASTNETSimple 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

Ammonium - <=ambient? <= ambient

pNO3 Ambient Ambient <=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

PM2.5 speciation sites (became IMPROVE in 2001 )

FilterPacks

8 Supplementary PM2.5 Speciation Sites (1993-2002)

IMPROVE Network, 200298 Sites with “complete” data, Mar 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

Sulfate Variation in Rural Areas

Comparison of CASTNET and IMPROVE Measurements in 2001

IMPROVEMarch 01 – Feb 02

CASTNET2001

Concentrations, STP

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

Nitrate Variation in Rural Areas

March 01 – Feb 02

IMPROVEMarch 01 – Feb 02

Better resolution will come from new ( 2002-2003) data

CASTNET2001

Gradient is overstated

Concentrations, STP

CASTNET 2001

HNO3 exhibit different spatial pattern

TNO3 also shows a MidWest to East gradient

HNO3

Concentrations, STP

NO3

2.7 + 2.1 = 4.8 ug/m3

NO3 HNO3 TNO3

0.8 + 2.0 = 2.8 ug/m3

NO3 HNO3 TNO3

CASTNET ComparisonsSulfates and Nitrates

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.

Western and Eastern Sites

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

PINSEK

BBE

CHAGRB

GLR MOR

ROM PND

LAV MEV

CAN

GRC

YEL

YOS

CAN

SEK

GRC

BBE

YEL

MEV

PIN CHA

GRBYOS

LAVPNDROM

MOR

GLR

-2

0

2

4

6

8

10

12

14

16

18

20

-50 0 50 100 150

DNO3- (%)

DN

O3

- / C

M (

%)

and

Tem

per

atu

re (

oC

)

Nitrate difference as a % of CM

Temperature

From: Rodger B. Ames and William C. Malm Comparison of sulfate and nitrate particle mass concentrations measured by IMPROVE and the CDN

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

BVL filterpak

amm_nitrate (PM2.5)

IMPROVE

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

93

-4

94

-3

95

-2

96

-1

96

-4

97

-3

98

-2

99

-1

99

-4

00

-3

01

-2

CDZ filter pak

ammonium_nitrate

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

93-4

94-2

94-4

95-2

95-5

96-2

96-4

97-2

97-4

98-2

98-4

99-2

99-4

00-2

00-4

01-2

QAK filter pak

ammonium_nitrate

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

MKG filter pak

ammonium_nitrate

IL

KY

OH

NW PA

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

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

Note: different than pNO3 loss with FRM measurements for PM2.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

CTH filter pak

ammonium_nitrate

0.0

1.0

2.0

3.0

4.0

5.0

6.0

93

-4

94

-3

95

-2

96

-1

96

-4

97

-3

98

-2

99

-1

99

-4

00

-3

01

-2

ARE filter pak

ammonium_nitrate

CTH, NY

0

1

2

3

0 1 2 3

Bondville, IL

0

2

4

6

8

10

0 2 4 6 8 10

Quarterly Average NO3: CASTNet vs PM2.5 Speciation

Good agreement in rural IL…. Relative Bias at Western NYS

CASTNET NO3, ug/m3

PM

2.5

Spe

cia

tion

3:21:1

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

• Derived from network average quartz filter field blanks to adjust annual averages

• Varies by 24-hr sampler volume– MetOne (SASS): 9.6 m3

– Anderson (RASS): 10.4 m3

– R&P: 14.4 m3

– URG (MASS): 24 m3

– IMPROVE: 32.8 m3

00.20.40.60.8

11.21.41.6

SASS

RA

AS

R&

P

MA

SS

IMP

RO

VE

OCblank,ug/m3

Preliminary OC Blank Corrections Used by Rao, Frank, et al*

* National Air Quality and Emission Trends Report 2003 Special Studies Edition http://www.epa.gov/oar/aqtrnd03/

Values used by Rao et al.

0.56

0.93 1.28

1.4

Newest Blank Corrections Are Slightly Different

Reference: Analysis of Speciation Network Carbon Blank Data DRAFT REPORT, Flanagan et alRTI International August 30, 2002

Newest Blank Corrections

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

SASS RAAS R&P MASS

OC

co

rrec

tio

n,

ug

/m3

For this analysis

Newest estimates

OC now corrected with Total Carbon value

OC wo Blank adjustment

y = 0.26x + 0.92

0

2

4

6

8

10

0 5 10 15 20 25

OC w Blank Adjustment has smaller intercept

y = 0.23x + 0.12

0

2

4

6

8

10

0 5 10 15 20 25PM2.5 Mass Concentration, ug/m3

OC concentration, ug/m3

Evaluation of OC blank correction for 12-month averages using measured OC vs PM2.5 mass

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 Variation in Rural Areas

March 01 – Feb 02

TCM=1.8*OC+ECBased on TCM= OC*1.8+EC

13 Selected Urban Sites are Paired with Rural Sites for “Urban PM2.5 Excess” Calculations

Fresno IndyS.L.

Tulsa

Missoula

SLC Bronx

Charlotte

Baltimore

Atlanta

Cleveland

Richmond

Birmingham

16 rural IMPROVE sites

13 urban STN sites

Fre

sno

/PIN

N

Mis

sou

la/M

ON

T

SLC

/GR

BA

Tuls

a/W

IMO

St.

Lou

is/3

Sit

es

Bir

min

gha

m/S

IP

Indy

/LIV

O

Atl

ant

a/2

Sit

es

Cle

vel

and

/MK

GO

Cha

rlot

te/L

IGO

Ric

hm

ond

/JA

RI

Bal

tim

ore

/DO

SO

Bro

nx/B

RIG

0

5

10

15

20

25

30

ug

/m3

Urban Increment Regional Contribution

Gravimetric Mass

Bottom: Regional ContributionTop: Urban Increment

Urban PM2.5 is Higher than Nearby Rural Concentrations

Top: Urban Bottom: Rural

12-month average PM2.5 mass from speciation samplers

- PM2.5 STN mass is affected by high filter blanks prior to ~August 2001

0

3

6

9

Sulfate Ammonium Nitrate TCM1.8 Crustal0

3

6

9

Sulfate Ammonium Nitrate TCM1.8 Crustal

0

3

6

9


0

3

6

9


Dolly Sods, WV

Rural IMPROVE site

(background)

Baltimore MD

STN urban site

Rural Concentrations Superimposed on Urban

Rural Concentrations Adjusted for Elevation differential

“Urban Excess” = Urban – Rural concentrations

Estimated Annual “Urban Excess” for Baltimore, MD

0

3

6

9


0

3

6

9


0

3

6

9


Top bars are urban concentrations

Bottom bars are nearby rural concentration

0

3

6

9


0

3

6

9


Fresno

Missoula

SLC

Tulsa

Birmingham

Indy

Cleveland

Charlotte

Richm ond

Baltim ore

Bronx

St Louis

Atlanta

Sulfa te :

0 .0 0.4 0.9

Am m onium :

0.0 0.9 1.9

N itra te :

0 .4 3.5 6.5

TC M (k=1.8):

2 .9 8.1 13.2

C rusta l:

0 .0 0.4 0.8

Range of TCM based on “k”= 1.4 to 1.8

(k=1.4)

Ambient Urban Excess Concentrations for 13 example areas

“Urban Excess” = urban concentration – regional background

Carbon is > 50-80% of the Urban Excess

Note: GM excess is higher in part, because of bias in STN mass thru June 2001, and because GM contains water.

0

5

10

15

20

25

Fre

sno/

PIN

N

Mis

soul

a/M

ON

T

SLC

/GR

BA

Tuls

a/W

IMO

St.L

ouis

/3 S

ites

Bir

min

gham

/SIP

S

Indy

/LIV

O

Atla

nta/

2 S

ites

Cle

vela

nd/M

KG

O

Cha

rlotte

/LIG

O

Ric

hmon

d/JA

RI

Bal

timor

e/D

OS

O

Bro

nx/B

RIG

urb

an e

xces

s, u

g/m

3

0%10%20%30%40%50%60%70%80%90%

exce

ss c

arb

on

, %

of

PM

2.5

Gravimetric mass Chemical Components %TCM1.4 of total

With straight inter-network comparison,

We see a large OC increment, but…. OC urban increment is potentially over stated

**

* “k” for OCM in rural areas is likely > 1.4, further reducing urban increment as presented

0

2

46

8

10

12

Fre

sno/

PIN

N

Mis

soul

a/M

ON

T

SLC

/GR

BA

Tuls

a/W

IMO

St.L

ouis

/3 S

ites

Bir

min

gham

/SIP

S

Indy

/LIV

O

Atla

nta/

2 S

ites

Cle

vela

nd/M

KG

O

Cha

rlotte

/LIG

O

Ric

hmon

d/JA

RI

Bal

timor

e/D

OS

O

Bro

nx/B

RIG

Regional Contribution Urban Increment (OCM k=1.4)

Note: Comparisons based on different thermo-optical techniques

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

0.00.20.40.60.81.01.21.4

Fre

sno/

PIN

N

Mis

soul

a/M

ON

T

SLC

/GR

BA

Tuls

a/W

IMO

St.L

ouis

/3 S

ites

Bir

min

gham

/SIP

S

Indy

/LIV

O

Atla

nta/

2 S

ites

Cle

vela

nd/M

KG

O

Cha

rlotte

/LIG

O

Ric

hmon

d/JA

RI

Bal

timor

e/D

OS

O

Bro

nx/B

RIG

Regional Contribution EC Urban Increment


By accounting for potential relative bias in reported EC The Urban EC Increment Can Be Bounded

Assuming IMPROVE EC > STN EC > ½ IMPROVE EC

0.00.20.40.60.81.01.21.4

Fre

sno/

PIN

N

Mis

soul

a/M

ON

T

SLC

/GR

BA

Tuls

a/W

IMO

St.L

ouis

/3 S

ites

Bir

min

gham

/SIP

S

Indy

/LIV

O

Atla

nta/

2 S

ites

Cle

vela

nd/M

KG

O

Cha

rlotte

/LIG

O

Ric

hmon

d/JA

RI

Bal

timor

e/D

OS

O

Bro

nx/B

RIG

Regional (lower est) Regional or add'l urban incr. EC Urban Increment


Upper Estimate EC urban excess

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

0

3

6

9


Elevation adjustment is a small technical correction to the “Urban Excess” calculation

Urban excess after

elevation adjustment

Concentration, ug/m3

Estimated Annual “Urban Excess” for Baltimore, MD

Concentration at 1158m (Dolly Sods) is 12% lower than a “sea level” estimate

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

Focus on Dolly Sods, WV Average Sulfate

March 01 – Feb 02

Elevation adjustment increases average DOSO sulfate to 4.8 ug/m3

http://capita.wustl.edu/CAPITA/CapitaReports/LocalPM10/LocalP10.HTML#combpandt

Local Condition Concentrations < High Elevation STP Concentrations


Local Condition Concentrations > Cold Area STP Concentrations


Local Condition Concentrations vs STP Concentrations

Q1 Average Nitrate

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

1995 1997 1998 1999 2000 2001 2002

Annual Average Nitrates

0.0

0.5

1.0

1.5

2.0

2.5

6 Northern

16 MWest/NE

15 Southeast

Large Inter-annual Variability in NO3, 2000-02

Northern

MidWest/NE

Southeast

Trend sites

CASTNET sites

Expressed as Ammonium Nitrates, 1.29*NO3

Use of PM2.5 MeasurementsUse of PM2.5 Measurements

• 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

use of national pm2.5 and speciation network measurements for model evaluation for presentation at...

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