Biomass Smoke Aerosol:Spatial and Temporal Pattern over the US
October [email protected]
Estimation of Smoke Mass
• The estimation of smoke mass from speciated aerosol data has eluded full quantification for many years
• CIRA, Poirot and others have • While full quantification is still not in hand, a proposed
approximate approach yields reasonably consistent results
• The smoke quantification consists of two steps:– Step 1: Carbon apportionment into Smoke and NonSmoke parts– Step 2: Applying factors to turn OCSmoke and OCNonSmoke into
Mass
Smoke Quantification using Chemical Data
– Step 1: Carbon apportionment into Smoke and NonSmoke partsCarbon (OC & EC) is assumed to have only two forms: smoke and non-smoke
OC = OCS (Smoke) + OCNS (NonSmoke)EC = ECS (Smoke) + ECNS (NonSmoke)
In each form, the EC/OC ratio is assumed to be constantECS/OCS = rs (In smoke, EC/OC ratio rs =0.08)ECNS/OCNS = rns (In non-smoke, EC/OC ratio rns = 0.4)
With thes four equations, the value of the four unknowns can be calcualted OCS = (rns*OC –EC)/(rns-rs) = (0.4*OC – EC)/0.32OCNS = OC-OCSECS = 0.088*OCSECNS = 0.4*OCNS
– Step2: Apply a factor to turn OC into MassThe smoke and non-smoke OC is scaled by a factor to estimate the mass
OCSmokeMass = OCS*1.5OCNonSmokeMass = OCNS*2.4
Smoke Excess OC – EC Calibration of Smoke Composition
• Smoke (excess) PM25, EC and OC yields calibration• Ratios for Kansas, Big Bend and Quebec smoke are similar• Good news for OC apportionment
PM25
ECOC
Smoke:EC/OC = 0.08PM25/OC = 1.5
EC/OC Ratio
OC–EC Non-Smoke Calibration by Iteration
• Non-smoke ratios are more difficult• EC/OC of about 0.2-0.4 is reasonable• Outside this range is not
EC/OC Non-Smoke = 0.15 EC/OC Non-Smoke = 0.2
EC/OC Non-Smoke = 1EC/OC Non-Smoke = 0.4
Negative Smoke – not Possible Maybe??
Maybe?? Too little non-smoke too much smoke
Smoke OC
Non Smoke OC
Measured and Reconstructed PM25 Mass
• Regional ‘calibration’ constants we applied to OC and Soil
OCS, OCNS and PM25 Seasonal PatternAverage over 2000-2004 period
PM25Mass
OCS Smoke
OCNS NonSmoke
Day of Year
Mexican Smoke
Agricultural Smoke
Urban NonSmoke Carbon
OC Smoke Spatial Pattern
Dec Jan Feb
Sep Oct Nov
Mar Apr May
Jun Jul Aug
EC NonSmoke
Dec Jan Feb
Sep Oct Nov
Mar Apr May
Jun Jul Aug
PM2.5 (blue) and ‘SmokeMass’ (red)
Smoke Events
Kansas Ag Smoke
Example OC ‘Smoke’ Events
Smoke Events
Seasonality of OC
Percentiles
• IMPROVE/STN Inconsistencies Not shown here
Great Smoky Mtn:
Episodic OC in the Fall season
Chattanooga::
Elevated and Persistent OC
GRSM Seasonal Pattern of Percentiles
PM25
OC
SO4
Soil
Episodic
Episodic
OC in Fall dominates episodicity - Smoke Organics?
Monthly Maps of Fire Pixels
• Fire pixels are necessary but not sufficient• Some Fire pixels produce more smoke aerosol than others …by at least factor of 5
NOAA HMS – S. Falke
Jan Feb Mar Apr
AugJun JulMay
Sep Oct Nov Dec
Smoke
Kansas Ag Smoke
No Smoke
Summary
• Developments (CIRA, Poirot, others) • OC and EC can be reasonably apportioned between Smoke
and NonSmoke components
• The reconstructed mass can be matched to the measured PM25
Problems of OC Apportionment
• Need to incorporate biogenic OC!• IMPROVE and STN OC don’t match
• Some coefficients may need regional/seasonal calibration