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Satellite Observations of Tropospheric Aerosols: More than Pretty Pictures

Satellite Observations of Tropospheric Aerosols: More than Pretty Pictures. Colette L. Heald Maria Val Martin, Bonne Ford, David Ridley. Let’s not forget: an institution that trained Jennifer Logan!. Symposium in Honour of Jennifer Logan, Harvard University May 10, 2013.

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Satellite Observations of Tropospheric Aerosols: More than Pretty Pictures

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  1. Satellite Observations of Tropospheric Aerosols: More than Pretty Pictures Colette L. Heald Maria Val Martin, Bonne Ford, David Ridley Let’s not forget: an institution that trained Jennifer Logan! Symposium in Honour of Jennifer Logan, Harvard University May 10, 2013

  2. Challenge: Heterogeneity of Atmospheric Aerosols GEOS-5 10 km aerosol model Many first order problems in aerosols (how much? what sources?) challenging to address because of the short lifetimes and varying properties of particles in the atmosphere. http://www.nasa.gov/multimedia/imagegallery/image_feature_2393.html

  3. Solution: Satellites! 1. Identify air masses 2. Context (spatial and temporal) 3. Track (investigate processing) 4. Identify sources 5. Constrain Budgets

  4. Transpacific Transport of Asian Aerosol Pollution as Seen by MODIS GEOS-Chem dust AOD GEOS-Chem Asian sulfate AOD MODIS AOD April 25, 2001 April 26, 2001 April 27, 2001 Most basic use of satellite observations (Identify events) [Heald et al., 2006]

  5. Satellite Measurements Show How High Aerosol Loading (AOD) is Associated with Both Local and Transported Smoke MODIS Terra AOD anomalies June 2002 August 2012 MT, WY, ID, WA Fires AZ, CA Fires CA Station Fire (2009) AZ Wallow Fire (2011) High Park and Waldo Fires Hayman Fire Continuous satellite observations can integrate across events and regions (Context) [val Martin et al., submitted]

  6. Dust From North Africa: Using Satellite Observations to Test Sources, Properties and Transport Air Quality (local & Americas) Ocean Fertilization (C cycle) Nutrient Supply (terrestrial productivity) Observed Saharan dust size distribution Simulated decrease in AOD [Highwood et al., 2003] Shifted mass to larger sub-micron sizes (less optically efficient). Reduces AOD in better agreement with satellite & AERONET observations

  7. Dust Removal Across the Atlantic Seasonally averaged AOD along Atlantic-outflow transects Assuming first order loss can estimate lifetime from slope of log-plots… Model removal too strong, especially in winter-spring (transport towards Amazon). Likely excessive removal along the ITCZ. We estimate dust lifetimes in model (~3 days) in spring about 50% of satellite-based estimate (> 6 days). (Aerosol processing) [Ridley et al., 2012]

  8. Atmospheric Ammonia: A Source of Particulate Matter and Emissions on the Rise… NH3 emissions major source of fixed N + = atmospheric acids (H2SO4, HNO3) Agriculture Animals Haber-Bosch Process (industrial production of NH3 fertilizer) has dramatically increased global food production. …degrading air quality? now and in the future? Atmospheric NH3 is sticky and semi-volatile with large dynamic range of concentrations: Difficult to measure. [Erisman et al., 2008]

  9. Satellite Observations Providing Critical New Insights! New satellite measurements from IASI offer unprecedented monitoring of NH3. Comparison with GEOS-Chem reveals springtime underestimate of emissions in the Midwest and year-round underestimate in the Central Valley of California. (Identify sources) [Heald et al., 2012]

  10. The Importance and Challenge(s) of Organic Aerosol Average aerosol composition for 37 campaigns in the NH oVOCs ? Secondary VOCs Primary [Zhang et al., 2007] Model-measurement comparison for 17 aircraft campaigns Range = 0.45-4.5 [Heald et al., 2011] Globally OA makes up 25-75% of total fine aerosol at the surface. Could become more even more important in the future with sulfate clean-up? Models drastically underestimate. Source(s) unclear.

  11. Using Satellite Observations to Constrain the Global Budget of Organic Aerosol TgC/yr Summer MISR AOD Simulated AOD from OTHER aerosol Residual = Organic Aerosol Satellite measurements indicate that total OA source is capped at 150 TgC/yr. This is still 3 times what is currently included in models. (Constrain budgets) [Heald et al., 2010b]

  12. Is Organic Aerosol Contributing to Climate Trends in the SE US? Portmann et al. [2009] suggest cooling over the E. US (1950 to present) associated with biogenic aerosol. Goldstein et al. [2009] show large AOD enhancement over SE in summer. DJF JJA CALIOP GEOS-Chem Strong seasonality seen in satellite AOD, but not surface PM2.5. Explanation: aerosol aloft confirmed by CALIOP – inorganic or organic? SENEX 2013! (Reveal interesting disconnects, probe 3D distribution) [Ford and Heald, submitted]

  13. Conclusions • Satellite measurements fill much needed observational gap for aerosols • But quantitative comparisons (moving beyond pretty pictures) can be challenging. • Interpretation of an integrated measurement (AOD), with complex retrieval algorithms. True uncertainties and biases not easily explored. • Retrieval algorithms not easily mimic’ed for models • Limited suite or sensitivity of aerosol precursor measurement from space (SO2, NH3, VOCs). • Daily snapshots (polar orbit) limit process quantification Funding Acknowledgements:

  14. First ever Official Atmospheric Chemistry Modeling Group Photo (2003) I might have been scared of Jennifer intimidated by inspired by

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