Function And Performance Of A New Real-time Black Carbon ... · 8 Optical Techniques: Reflection...
Transcript of Function And Performance Of A New Real-time Black Carbon ... · 8 Optical Techniques: Reflection...
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Function And Performance Of A New Real-timeBlack Carbon Monitor During the 2003-2004
Fresno Study
2005 AAAR PM Supersites Program & Related StudiesFebruary 8, 2005, Atlanta, GA
5C-2
Kevin Goohs, Thermo Electron Corporation, Franklin, MADr. Andreas Petzold, Deutsches Zentrum fuer Luft- und Raumfahrt,
Oberpfaffenhofen, Wessling, GermanyScott Scheller, CARB, Fresno, CA
John Bowen, Dana Trimble, et al., DRI, Reno, NV
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Basic Concepts
Black Carbon
• Major component of PM2.5
• Typically 25-50%, and up to 70% for PM2.5
• Three Classes of Carbon: 1. elemental or black (EC)
2. Organic (OC)
3. Carbonate (CC)
• Total Carbon (TC) = EC + OC + CC
Aerosol Monitoring – Black Carbon
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Basic Concepts
Black Carbon
• EC: Anthropogenic Sources (mobile sources and PICs)
• OC: Anthropogenic Sources (1o and 2o aerosols)
• CC: Soil Related (<5% of TC)
Aerosol Monitoring – Black Carbon
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Sampling Techniques
Non-Destructive and Indirect (Optical)• Filter Sample• Laser Transmission and/or Reflection• Method accuracy can be concentration and composition dependent
Aerosol Monitoring – Black Carbon
Destructive and Direct• Pre-fired Quartz or Glass Fiber used as a gravimetric sample.• Thermal Processes (methods vary in T, rate ∆T, Oxidation)• Carbon thermally evolved from sampled particulate• Similar TC results; EC & OC results vary from method to method
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Sampling Techniques
Destructive (thermal optical transmittance and reflectance)
• Advantages: Recognized Reference Methods, TotalCarbon Measurements and breakdown of EC, OC, CC
• Disadvantages: Limited Time Resolution (typically 24-hr),Turnaround, Operating Costs, Laboratory Costs, and ECis an estimate method dependent
Aerosol Monitoring - Black Carbon
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Sampling Techniques
Non-Destructive (laser/light transmittance and reflectance)
• Advantages: Low Operational Cost, Better TimeResolution, Increased Statistical Database, InstantaneousTurnaround (Index Reporting, Increased Knowledge of airshed characteristics), lower capital cost
• Disadvantages: Limited to EC, site specific with somemethods
Aerosol Monitoring - Black Carbon
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Optical Techniques: Transmission (Gundel et al., 1984)
Aerosol Monitoring - Black Carbon
BCATN SIIATN σ=−=0
ln100
∗ σATN reported to range from 5 m2 g-1 to > 20 m2 g-1, depending on the type ofsampled aerosol (Liousse et al., 1993; Petzold et al., 1997)
** An analysis of attenuation measurements and independent measurements ofatmospheric black carbon via a thermal method showed that the σATN value isaffected by the fraction of exclusively light-scattering components of the aerosol(Petzold et al., 1997).
*** This conclusion was recently confirmed by a study on the Particle SootAbsorption Photometer (PSAP; Radiance Research Inc. Seattle, USA) (Bond et al.,1999).
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Optical Techniques: Reflection (Bailey and Clayton, 1982)
Aerosol Monitoring - Black Carbon
• σREF aerosol study indicated marginal dependance (Kopp et al., 1999).
• σATN and σREF are different due to aerosol layer and filter matrix interaactions(Kopp et al., 1999)
• Concluded σATN and σREF differ from the specific absorption cross section σabs forairborne black carbon particles because airborne particles do not face any multiplescattering processes caused by a surrounding filter matrix.
• The deviation from σabs can reach 30% for aerosol deposited on membrane filter(Hitzenberger et al., 1993), while in the case of a fiber filter matrix it may become afactor of 2 and more (Petzold et al., 2001).
BCREF SRRREF σ2ln100
0
=−=
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Aerosol Monitoring – Black Carbon
Example
inc ident rad ia tion
aeroso l layer
back scatteredrad ia tion
m ultip lere flec tions(d iffuse)
filte r m atrix
transm itted and fo rw ard -scatte red
rad ia tion
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Aerosol Monitoring – Black Carbon
Development Goals
• Apply radiative transfer analysis of a particle loaded filter
• Account for multiple-scattering effects
• Apply knowledge of the optical field in the forward andbackward hemisphere of the aerosol-filter system.
• Develop a simple instrument for continuous black carbonmonitoring
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Aerosol Monitoring – Black Carbon
Development
• Scattering phase function of blank and particle loaded filtersdetermined using a polar photometer
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Aerosol Monitoring – Black Carbon
Development
• angular distribution of radiation for a blank filter with aerosol composition
• angular distribution into forward hemisphere independent of aerosol composition
• angular distribution into the back hemisphere is dependent with the absorbing aerosolreducing scatter and scattering aerosol increasing scattering w/respect to filter matrix.
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Aerosol Monitoring – Black Carbon
Principal of Operation
θ0
θ1
θ2
θ0
θ1
θ2
• Aethelometer
• PSAP
• MAAP
Transmittance Only
Forward Scattering, Back Scattering, andTransmittance θ0 = 0°, θ1 = 130°, θ2 =165°
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Aerosol Monitoring – Black Carbon
Model 5012 MAAP Continuous Black Carbon Monitor: Multi-Angle Absorption Photometer
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Thermo Model 5012 MAAP
Bench StudiesReno Aerosol Optics Study June 2002* MAAP shows good agreement with reference absorption over a wide range of absorption and ω0•Filter transmission methods (PSAP, aethalometer) require improved corrections for scattering effects, & filter loading (Sheridan et al., 2003)
0
50
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0 50 100 150 200Reference Absorption (M m -1 @ 660 nm)
MA
AP
Abs
orpt
ion
(Mm
-1 @
660
nm
)
1:1 line
ap(MAAP) = 1.04*( ap(REF)) + 1.0,r2=0.99
σ σ
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Bench StudiesReno Aerosol Optics Study June 2002
Thermo Model 5012 MAAP
The plot to therightdemonstrates thestability of theMAAP with lowCarbon and highscatteringaerosol.
White Aerosol Runsat DRI Reno, NV June 2002
0.0
2.0
4.0
6.0
8.0
10.0
12.0
1 2 3 4 5 6 7 8 9
Bab
s (M
m-1
)Aethalometer 699nm MAAP 670 nm
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Thermo Model 5012 MAAP
Bench StudiesFranklin, MA Collocated Precision Evaluation June 2003
MAAP 1 & 2 On Bench w/Room TSP and General Carbon Vane ExhaustFranklin, MA 6/10-6/12/2003 : 30 Minute Data Points
0
200
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600
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20:00
22:00 0:0
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:0012
:0014
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:0020
:0022
:00 0:00
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Time
BC
ng/
m3
Series1Series2
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Thermo Model 5012 MAAP
Ambient StudiesFranklin, MA Collocated Precision Evaluation June 2003
Collocated MAAPs w/PM2.5 Inlet - Field Calibrated for Ta, Pa, and QaOvernight Collocation at Franklin, MA Shelter June 17-18th, 2003 : 30 Minute Data Points
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Time (hh:mm)
MA
AP
BC
Con
c (n
g/m
3)
MAAP 1MAAP 2
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Thermo Model 5012 MAAP
Ambient StudiesFranklin, MA Collocated Precision Evaluation June 2003
Collocated MAAPs w/PM2.5 Inlet - Field Calibrated for Ta, Pa, and QaOvernight Collocation at Franklin, MA Shelter June 17-18th, 2003 : 30 Minute Data Points
y = 0.990x + 3.386R2 = 0.997
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0 100 200 300 400 500 600 700 800 900
MAAP 1 (ng BC/m3)
MA
AP
2 (n
g B
C/m
3)
MAAP 2Linear (MAAP 2)
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Thermo Model 5012 MAAP
Ambient StudiesFresno, CA Supersite Collocated Results
R e a l T im e 5 m in u te A v e ra g e M A A P B la c k C a rb o n a t F re s n o , C A 1 2 /8 -1 5 /2 0 0 3 b a s e d o n R a w D a ta
-2 0 .0 0
-1 0 .0 0
0 .0 0
1 0 .0 0
2 0 .0 0
3 0 .0 0
4 0 .0 0
16:4
8:00
20:3
8:00
0:37
:00
4:22
:00
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:00
11:4
3:00
15:2
8:00
19:1
3:00
23:0
3:00
2:56
:00
6:48
:00
10:3
3:00
14:1
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18:0
3:00
21:5
6:00
1:49
:00
5:42
:00
9:27
:00
13:2
0:00
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5:00
20:5
5:00
0:49
:00
4:34
:00
8:19
:00
12:0
9:00
15:5
4:00
19:3
9:00
23:3
3:00
3:22
:00
7:07
:00
10:5
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14:3
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18:2
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2:00
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:00
6:02
:00
T im e o f D a y (h h :m m )
MA
AP
BC
(ug/
m^3
)
C B C _ 1 C B C _ 2
N o is e a n d n e g a tiv e v a lu e s a re a s s o c ia te d w ith M A A P 2 R e f le c t io n S ig n a ls e ith e r d iv e rg in g ra p id ly o r th e R e f le c t io n 1 6 5 in c re a s in g w h ile 1 3 5 c o n tin u e s to d e c re a s e .
A t le a s t th is c a n b e e x p la in e d . I t m a y b e re la te d to a n in te rm m ite n t c o n n e c tio n e r ro r s in c e M A A P 2 d id s h o w s o m e p o o r b e h a v io r n e a r th e s ta r t o f th e te s t a n d is a ls o in s ta lle d o n th e ro o f . V ib ra t io n m a y b e c a s u in g th e a s s u m e d p o o r c o n n e c tio n . F a c to ry c o n n e c to rs h a v e a lre a d y b e e n u p d g ra d e d to a v o id fu tu re p o o r c o n n e c tio n s .
M A A P 1 d o e s n o t s h o w th is p o o r b e h a v io r .
O th e rw is e , th e s e in s tru e m n ts a re t ra c k in g v e ry n ic e ly .
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Thermo Model 5012 MAAP
Ambient StudiesFresno, CA Supersite Collocated Results
Thermo Electron Model 5012 MAAP BC Monitor Hourly MAAP 2 vs MAAP 1 : Fresno, CA 12/10 - 12/31/2003
y = 1.09x + 0.01R2 = 0.99
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MAAP 1 (ug/m3)
MA
AP
2 (u
g/m
3)
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Thermo Model 5012 MAAP
Ambient StudiesFresno, CA Supersite EC Data Comparison
MAAP & Elemental Carbon Time Series Fresno, CA 1/10 - 8/7/2004
0.0000
0.5000
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1/10/2
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1/17/2
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1/24/2
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1/31/2
004
2/7/20
042/1
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8/200
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/2004
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004
3/27/2
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/2004
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/2004
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/2004
Date (mm/dd/yyyy)
BC
& E
C D
ata
(mic
rogr
ams
per c
ubic
met
er)
ECTC MAAP
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Thermo Model 5012 MAAP
Ambient StudiesFresno, CA Supersite EC Data Comparison
MAAP BC and EC Time Series within 2σ Uncertainty
0.0000
0.5000
1.0000
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3.0000
3.5000
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4.5000
1/4/20
041/1
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8/200
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42/1
/2004
2/8/20
042/1
5/200
42/2
2/200
42/2
9/200
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/2004
3/14/2
004
3/21/2
004
3/28/2
004
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1/200
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/2004
5/9/20
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/2004
6/13/2
004
6/20/2
004
6/27/2
004
7/4/20
047/1
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47/2
5/200
48/1
/2004
BC & EC Data
Dat
e (m
m/d
d/yy
yy)
EX_low EC_up MAAP
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Thermo Model 5012 MAAP
Ambient StudiesFresno, CA Supersite EC Data Comparison
MAAP vs FRM DRI ECFresno, CA 1/10 - 8/7/2004
y = 0.95x - 0.04R2 = 0.97
0
0.5
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1.5
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3.5
0.0000 0.5000 1.0000 1.5000 2.0000 2.5000 3.0000 3.5000 4.0000
EC (micrograms per cubic meter)
BC
(mic
rogr
ams
per c
ubic
met
er)
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• Insensitive to Aerosol Properties• Accounts for Scattering Artifacts of non-carbon aerosol• Excellent Performance at DRI Bench Study, June ’02
Model 5012 MAAPFeatures and Benefits
• Automatic Filter Change, temporal and mass loading driven• Data Output via Analog, Serial, and Display• Long term networking ability• Microprocessor controlled, Quality Assurance Features
• 1-yr data storage and minimum 6 month filter tape• Excellent candidate for ambient light absorption studies for
visibility monitoring (Bext = Babs + Bscat)
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• Analog I/O Expansion Board: Can be used withmeteorological sensors
Model 5012 MAAPFeatures and Benefits
• Filter Strip Printer for quasi-Chain of Custody• Foil Separation for limited filter stain speciation
• Significant mass loading for post collectionanalysis
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Ambient• Air Toxic Monitoring• AQ Index Reporting• Fenceline Monitoring• Air shed Characterization• Visibility research• Tropospheric Carbon
Studies
Model 5012 MAAPApplications
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Conceptual SourceMonitoring• CEM w/ Dilution
Probe• Combustion
Efficiency Indicator• Diesel Shop Testing
Model 5012 MAAPApplications
…Research, Development, &Application
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THANK YOU
Dr. Judy Chow
Dana Trimble
John Bowen
Scott Scheller
Dr. Andreas Petzold