This document summarizes ambient measurements of black carbon taken using a new Soot Particle-AMS (SP-AMS) instrument in conjunction with other instruments during a field deployment in Los Angeles from May to June 2010. Key findings include: 1) Black carbon mass showed clear daily and weekday/weekend patterns, consistent with previous observations in LA. 2) Some evidence was found of a daily pattern in black carbon coatings linked to nitrate. 3) Volatility of coatings was consistent with expectations, but quantification of black carbon mass and coatings using the SP-AMS requires further calibration and focusing development. 4) The SP-AMS shows potential for measuring black carbon mass and coatings

1. AGU FALL MEETING 2010: A14A-05, 13 December 1700
Ambient measurements of black carbon
using the new SP-AMS in conjunction with
other instruments
Hugh Coe, James Allan, Jonathan Taylor, Michael Flynn, Paul
Williams, Gavin McMeeking, Greg Kok, Darrel Baumgardner, Tim
Onasch, Ed Fortner, John Jayne and Doug Worsnop
Image courtesy of SRTM Team NASA/JPL/NIMA

2. The Soot Particle-AMS

3. BC and absorption instrumentation

4. Field deployment: Cal-NEx Los Angeles
Cal Tech ground site
(northern Los Angeles, CA).
15 May – 15 June 2010

5. Black carbon mass
spurious SP-AMS signal?

6. Weekday/weekend and diel patterns
3-9 June weekdays only
1 std deviation
mean
Local morning traffic peak?
Marr and Harley, ES&T, 2002 – CENTRAL VALLEY
heavy-duty
Entire campaign
light-duty
Weekend effect has been observed in LA
before: e.g., Turpin and Huntzicker (1991) ;
Young et al. (1994)

7. Black carbon coatings: 3-9 June
early morning pattern in mixing state/coating

8. Black carbon coatings II: 3-9 June
for 150 nm BC core only!
SP-AMS coatings normalized by
absorption/SP2 rBC

9. SP-AMS focusing and BC “size”?
No change in Aeth response
How do we
interpret
coating
information?

10. Volatility
SP-AMS PMF analysis SP2 coating information
0.6
BC
LV-OOA
SV-OOA
Attenuation
BBOA
0.4 HOA
SO4
NO3
0.2
0.0
60 80 100 120 140 160 180 200 220°C
Denuder Temperature (°C)

11. Conclusions
• BC mass shows clear diel and
weekday/weekend patterns at Cal Tech site
• Some evidence of diel pattern in BC coatings
linked to nitrate
• No clear effect on Aethalometer absorption!
• Volatility of coatings consistent with
expectations
• SP-AMS capable of measuring BC mass and
coatings; quantification a major development
target (calibration & focusing)

12. • Thanks to:
– Cal Tech for hosting and CARB for infrastructure/logistics support!
– Jochen Stutz (UCLA)
– Joost DeGouw, Karl Froyd, Tim Bates, Shane Murphy (NOAA)
– Jose Jimenez, Patrick Hayes, Amber Ortega (CU Boulder)
– John Seinfeld, Puneet Singh (Caltech)
– Paola Formenti (Aerodyne)
– Jim Smith (NCAR) MC4
NE/H008136/1
– Manuel Dall’Osto (IDAEA-CSIC)
– Stefano Decesari (CNR Bologna)
– The rest of the Calnex-LA team

14. Air from stack
PM1 cyclone Drier
Thermal Bypass
denuder
Automated Valve
Aethalometer SP-AMS PASS SP2

15. 200 Numbers denote mobility diameter in nm 350
225
Coefficient values ± one standard deviation
a =-7.153 ± 21.2 200
b =181.48 ± 28.1
150
SP-AMS ion rate (Hz)
100
500
250
50
125
80
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2
-3
SP2 mass (µg m )

16. • PIKA analysis
needed
• V mode was
sufficient to
resolve carbon
clusters