1. Measurement of biomass burning aerosol with an Aerodyne Q-AMS during DABEX (and DODO) Gerard Capes, Hugh Coe, Paul Williams

2. AMS main result: the CO plot Increasing distance from source (N and W) moves along the curve Scatterplots of all data from all flights DABEX & DODO1 Inorganic mass fraction is insignificant in comparison

3. Contrast with anthropogenic pollution Data from the Po Valley in northern Italy (ADRIEX) shows an increase in the Organic to CO ratio as the aerosol ages. A similar trend has been observed for UK pollution during photochemical outbreaks (AMPEP experiment). European polluted environmen t

4. Does anything else follow the CO plot? Scattering coefficients change over the plot – do the optical properties (SSA) of the aerosol change over time? Total number concentration suggests this is just dilution, i.e. not losing particles to coagulation: any coagulation has likely already occurred before FAAM measured it

5. PCASP size distributions as function of CO B158 B166 B162 The shape of the distribution doesn’t correlate strongly with the CO concentration – also points to dilution

6. Mass spectra – key fragments m/z43 Both saturated ( C 3 H 7 + ) and oxidised compounds (aldedhydes and ketones CH 2 CHO + CH 3 CO + ) m/z44 CO 2 + Oxidised compounds m/z57 C 4 H 9 + Saturated hydrocarbons (fresh aerosol) m/z60 Levoglucosan marker Rami Alfarra, PSI

7. Ageing of the aerosol: changes in chemical functionality 43 44 57 60 43 44 57 60 43 44 57 60

8. Ongoing work… Compare AMS size distributions from SLRs with PCASP to derive relationship between vol and mass distribution – hence get a check on effective density and real part of refractive index Any evidence for photochemistry? Check whether chemical changes correlate with ozone formation Why do we not see SOA in BB layers? Collaborative work with climate models