1. What satellite and aircraft observations can tell us about the organic aerosol budget Colette L. Heald 5 th International GEOS-Chem Meeting May 2, 2011 Acknowledgments: David Ridley, Easan Drury, Sonia Kreidenweis, Hugh Coe, Matthew Jolleys, Jose Jimenez, Rodney Weber, Roya Bahreini, Ann Middlebrook, Lynn Russell, Armin Wisthaler, Thomas Karl, Jennifer Murphy, Joost de Gouw, Carsten Warneke

2. FIRST… SOME INTRODUCTIONS Bonne Ford, graduate student Poster: Tuesday Luke Schiferl, graduate student Kateryna Lapina, Postdoc Talk: next! Dave Ridley, Postdoc Talk: after lunch Maria Val Martin Research Scientist just joined group!

3. CAN SATELLITE OBSERVATIONS SHED ANY LIGHT ON THE BUDGET OF OA? SURFACE REFLECTANCE Bottom-up calculations suggest that SOA source may be anywhere from 140-910 TgC/yr [Goldstein and Galbally, 2007]. Organic aerosol Sulfate Dust Sea Salt Nitrate SATELLITE AOD Assumptions: Optical Properties Size Distributions Aerosol Distributions AEROSOL SPECIATED MASS CONCENTRATIONS Soot

4. ATTRIBUTE ENTIRE MODEL UNDERESTIMATE OF AOD TO ORGANICS Estimate that ~150 TgC/yr source is required to close the MISR-GEOS-Chem* discrepancy. DJFJJA MISR GEOS-Chem* MISR- GEOS-Chem* *excluding OA (v8-02-04)

5. This is more than THREE TIMES what is currently included in global models…. BUT at the low end of Goldstein & Gallbally [2007] range. HAVE WE REDUCED THE UNCERTAINTY ON THE OA BUDGET? 910 47 Existing GEOS-Chem sources 140 Our satellite top-down estimate 150 Range estimated by: Goldstein and Galbally [2007] All units in TgCyr -1 [Heald et al., 2010]

6. DIGGING IN DEEPER: 17 AIRCRAFT FIELD CAMPAIGNS * All AMS measurements, except ITCT-2K4 (PILS) and ACE-Asia (filters). 2001-2009 Aircraft constraints on the organic aerosol distribution through depth of troposphere in remote, polluted and fire influenced regions.

7. COMPARISON OF VERTICAL PROFILE GEOS-Chem: v8-03-01 with GEOS-5 met product (GEOS-4 for ACE-Asia only), simulations matched to year and location of aircraft, standard POA, BSOA and ASOA.

8. OVERALL COMPARISON OF OA SIMULATION In median observations range from 0.45-4.5 of simulated. Difference is largest close to source.

9. CAN WE ATTRIBUTE THE MODEL UNDERESTIMATE? Adding ~100 Tg/yr source of ASOA (as suggested by Spracklen et al., 2011) improves comparison in polluted regions, but leads to too much OA aloft and in remote regions. OA sink? Higher volatility OA? [Heald et al., in prep]