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How do aerosols affect air quality, the human environment, and natural ecosystems?

Mian Chin. How do aerosols affect air quality, the human environment, and natural ecosystems?. For AeroCenter Update, March 8, 2008 (Year of the Rat). Many others. and. Aerosol affects air quality – Emission, transport, and amount of surface particulate matter. PM air quality.

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How do aerosols affect air quality, the human environment, and natural ecosystems?

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  1. Mian Chin How do aerosols affect air quality, the human environment, and natural ecosystems? For AeroCenter Update, March 8, 2008 (Year of the Rat) Many others and

  2. Aerosol affects air quality – Emission, transport, and amount of surface particulate matter

  3. PM air quality • Aerosol particles, also called particulate matter (PM) in air quality terms, exert health and environmental problems when in high concentrations AeroCenter Update 2008

  4. Sources of PM: • Local/Regional: • Power plants, automobiles, fires, dust, and other natural sources (trees, volcanoes) • Transboundary transport from outside: • Pollutants, smoke, and dust generated from other regions that can be transported into region of interest • The extent of impact of long-range transport and regional emissions on air quality depends on the amount emitted locally and the vertical locations of PM from outside regions AeroCenter Update 2008

  5. MODIS AOD GEOS-4 model AOD From: Peter Colarco Red: fine mode Green: coarse mode Green: carbonaceous or sulfate Orange: dust Other color: mixture Asian dust over central Pacific during INTEX-B (Spring 2006) Langley aircraft lidar Ed Bowell From: Ken Pickering & Tom Kucsera 3-day OMI AI Exposure Sources and transport from observations and models From: Yoram Kaufman AeroCenter Update 2008

  6. What can satellite data tell us about the long range transport of pollution beyond pretty pictures? A Satellite-based assessment of trans-Pacific transport of pollution aerosol Hongbin Yu, Lorraine Remer, Mian Chin, Huisheng Bian, Richard Kleidman, Thomas Diehl, JGR in press, 2008 (Kaufman special issue)

  7. MODIS seeing pollution from China spilled over NW Pacific on Jan. 1, 2007. Anthropogenic AOD MODIS Anthropogenic (pollution + smoke) AOD over oceans derived from MODIS Yoram Kaufman’s formula: • Whereτ, τa and τm are total, anthropogenic, and maritime aerosol optical thickness • fτ, fd, fm, fa are fractions of fine mode, dust, maritime, and anthropogenic aerosol optical thicknesses • τa is derived using a modified/ improved Kaufman method • Using vertical information from GLAS and CALIPSO, RH data from AIRS, and mass extinction efficiency from field measurements to convert τa to mass flux From: Hongbin Yu (Yu et al., 2008) AeroCenter Update 2008

  8. Measurement-based estimate of transpacific transport of anthropogenic aerosols • Using aerosol products from multiple satellite sensors (MODIS, GLAS, CALIPSO, AIRS) and from field measurements • ~ 18 Tg/year pollution aerosol is exported from East Asia (and its upwind regions) to NW Pacific • ~ 4.5 Tg/year (25%) reaches the west coast of North America • This imported amount is about 15% of the total anthropogenic emissions in U.S. and Canada • GOCART and GMI model simulations show similar magnitudes with satellite-based estimate, which is the total column amount Export Import From: Hongbin Yu (Yu et al., 2008) AeroCenter Update 2008

  9. The above study is an estimate of total column flux – how does this transport affect the surface air quality? Intercontinental transport of pollution and dust aerosols: Implications for regional air quality (A modeling study) Mian Chin, Thomas Diehl, Paul Ginoux, William Malm, ACP 2007

  10. The impact is critically dependent on vertical extent of transported aerosol plume GOCART model study Leaving Asia Entering N. Am. • Asian pollution: • Max in at surface leaving Asia • Max above surface (1.5 – 4 km) entering North America • Requiring downward mixing to send stuff to North American surface • European pollution: • Contributing 10 – 50% in the “Asian outflow”! Ratio of imported to locally emitted athropogenic fine mode PM at surface: - From 14% in NW to 3% in SE U.S. AeroCenter Update 2008

  11. Other studies showing the importance of aerosol vertical profiles to map the column amount to surface PM: Using GEOS-CHEM model to map MISR data to surface PM2.5 – Y. Liu, Kourtakis, R. Kahn, et al, JAWMA 2007 3-D Air Quality System project – R. M. Hoff, K. McCann, H. Zhang, A. Prados, and J. Engel-Cox Using Giovanni tool to map MODIS AOD to surface PM2.5 – A. Prados and Greg Leptoukh

  12. SO4 PM2.5 Eastern US MISR-Constrained Model Western US EPA Surface Measurements MISR & GEOS-Chem – Mapping near-surface pollution(Liu, Krukakis, Kahn et al., 2007) • MISR provides total-column AOT over land to constrain model • MISR also gives particle shape to separate dust & spherical particles --> much better result • GEOS-CHEM provides aerosol vertical distribution + detailed spherical-particle chemical speciation AeroCenter Update 2008

  13. 3-D Air Quality System (R. Hoff et al.) • Integrate NASA satellite sensor and lidar data into EPA’s air quality data systems • Provide greater accessibility and usability of satellite and lidar data to users of these systems • Enable monitoring in horizontal and vertical dimensions for forecasting and retrospective analysis Remapped MODIS 12x12 CMAQ Gridded AOD product MODIS 10x10 granule AOD product Calipso and UMBC Lidar data mapped to EPA PM sites AeroCenter Update 2008

  14. Assessing U.S Air Quality with Giovanni (Ana Prados and Greg Leptoukh) • Data sets: MODIS Terra and Aqua AOD, EPA PM2.5, CALIOP, OMI NO2 and Aerosol Index • Services: include AOD/PM2.5 correlation maps and scatter plots, and image loops for examining long range transport of pollutants May 22nd, 2007: Smoke over north Carolina. High AOD and low PM2.5 (r=0.54). There is also haze in the southeast Improved correlation over this region when excluding smoke areas (r=0.80) Level-3 MODIS AOD Giovanni data sets and tools help provide a more complete understanding of the origin, evolution, and vertical distribution of aerosol pollution over the continental U.S. EPA PM2.5 (ug/m3) AeroCenter Update 2008

  15. Remarks on aerosol impact on air quality • Key quantities: Vertical distribution; composition; and particle size • Current satellite data have limited information on these quantities • There are innovative methods to estimate the transport and “retrieve” surface PM from current satellite observations but with large uncertainties • Future satellite mission should focus on improving capabilities on observing the key quantities with adequate spatial coverage and accuracy AeroCenter Update 2008

  16. Aerosol affects human environment – Global dimming/brightening

  17. Multi-decadal change of solar radiation reaching the surface • Solar radiation reaching the surface (Ssfc) is the primary energy source for life, and any change of this radiation could substantially affect the climate, hydrological cycle, and ecosystems • Surface water evaporation • Soil moisture • Crop yield • CO2 uptake AeroCenter Update 2008

  18. Stations over Japan and Russia 52 stations avg over China SW irradiance Anthropogenic SO2 emissions Multi-decadal change of solar radiation reaching the surface – global dimming/brightening • Long-term observations of Ssfc have shown a decline in solar radiation up to 1990 at several different regions of the world (dimming) • Recent measurements have indicated an increase of Ssfc since about 1990 over many regions of the world (brightening) • Anthropogenic emission change mirrors the change of Ssfc, suggesting possible roles of aerosols • Many other factors can also contribute to the Ssfc change, such as clouds • Global or regional or local? Total Other regions East Asia Former USSR Eastern Europe OECD Europe U.S.A. From: David Streets (Streets et al., 2004, 2006) AeroCenter Update 2008

  19. Long-term variations of AOD (1979 – 2006)(Preliminary GOCART results) • Using time-varying anthropogenic emission 1979 - 2006 from David Streets • Compiling volcanic, biomass burning, aircraft/ship emissions (T. Diehl) • Calculating dust and sea-salt emissions as a function of wind speed and surface conditions Global ocean avg AOD, 60S – 60N Global land avg AOD, 60S – 60N Figure from: Thomas Diehl AeroCenter Update 2008

  20. Sulfur Carbonaceous Dust Sea-salt Emission AOD 550 nm Emission vs AOD 1998 1992 1993 1991 1997 1982 What is the relationship between aerosol emission, AOD, and Ssfc? (Preliminary GOCART results – annual avg) AeroCenter Update 2008

  21. Remarks on aerosol impact on surface radiation • Key quantities: direct and diffuse SW solar radiation at the surface, under both cloudy and clear skies, and aerosol amount and optical properties • Current satellite retrieval of surface radiation (e.g. from ISCCP or CERES) suffers from difficulties in specify aerosol amount and optical properties • Current surface radiation networks are limited for adequate global assessment • Long-term monitoring of surface radiation and aerosols from ground-based network is needed • Better retrieval of surface radiation from space requires much better knowledge of aerosol properties AeroCenter Update 2008

  22. Aerosol affects natural ecosystem – Dust and ocean productivity

  23. Iron supply is a limiting factor on phytoplankton growth over vast areas of the ocean Deposition of dust transported from deserts is believed to be the main source of iron to the open ocean However, dust-marine productivity connection depends on the amount of soluble iron, Fe(II) Connection between dust and ocean biology Global iron and dust connections From: Jickells et al., Science 2005 AeroCenter Update 2008

  24. Dust as a Tracer of Climate Change in Antarctica and as modulator of Phytoplankton Activity • Phytoplankton activity is very sensitive to changes in nutrient availability (particularly in the Southern Ocean) Artificially seeded Fe in the Southern Ocean Visible chlorophyll enhancement afterwards Soiree Experiment, Edward et al, Nature 2000) AeroCenter Update 2008

  25. Satellite retrieves both ocean Chl. (e.g. MODIS and SeaWiFS) and dust aerosols (e.g. MODIS coarse mode, MISR non-spherical), which can be potentially used to link dust to ocean productivity But absorbing aerosols (dust, smoke) remain problematic in ocean color data processing Global distributions of Chl. and aerosol Chlorophyll Concentration From: W.E. Esaias January 2001 Aerosol Optical Thickness From: C. McClain April 2001 AeroCenter Update 2008

  26. MODIS Aerosol Optical Depth OMI Aerosol Index A combination of MODIS and OMI observations shows dust traveling a long way in the South Atlantic • Observation of dust in the SO is very difficult because: • Very cloudy --- > very few clear sky retrievals ----- > sampling problem • Dust activity is episodic and in pulses. • Only a combination of satellite retrievals and surface (ship) can help to understand dust transport and detection in the SO as this example shows. Gassó & Stein, GRL 2007 AeroCenter Update 2008

  27. Obtain dust AOD τd: Estimate vertical profiles using “virtual lidar” – correlations with the NCEP winds Convert dust AOD to mass Using wind speed and Terra/Aqua dust mass differences to estimate the dust mass transport Derive dust deposition Kaufman et al. 2005 estimated: 240 ± 80 Tg of dust are transported annually from Africa to Atlantic 50 Tg fertilize the Amazon Basin 50 Tg reach the Caribbean 20 Tg return to Africa and Europe Dust deposition over Atlantic Ocean derived from Terra + Aqua MODIS Yoram Kaufman’s method: Estimated dust flux, Kaufman et al., JGR 2005 AeroCenter Update 2008

  28. Remarks on aerosol impact on ocean biology • Key quantities: dust aerosol amount and deposition, soluble iron, ocean phytoplankton/chlorolphyll • Current satellite retrievals of ocean color requires accurately accounting for aerosol “interference” • It is very difficult to observed dust when clouds present • It is even more difficult to know if iron from dust is active • Future satellite observation should have a better capability to detect dust even in cloudy conditions with adequate spatial coverage • Although dust deposition cannot be directly observed by satellites, it can be derived with higher temporal satellite coverage (several times/day) to see aerosol moving and change AeroCenter Update 2008

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