Transport of aerosols: Regional and global implications for air quality (, weather, and climate)

Transcription

1 Transport of aerosols: Regional and global implications for air quality (, weather, and climate) Mian Chin, Hongbin Yu, Thomas Diehl NASA Goddard Space Flight Center, U.S.A.

2 Long-range transport of aerosols: Long-range transport of aerosols from their source locations to other regions has been studied for more than 30 years Scope ranging from air quality to climate change As a pollutant, aerosols (aka PM) can Pose serious health risks Degrade visibility As a climate forcing agent, aerosol can mask some greenhouse warming effects affect the hydrological cycle modify weather patterns at locations

3 Satellite observations on longrange transport Dust and fire: OMI absorbing aerosol index July 2005 Figure from Mark Schoeberl

4 Transport of dust and pollution from MODIS MODIS AOD APR Red: fine mode Green: coarse mode Figure from Yoram Kaufman and Reto Stoc

5 What can satellite data tell us about the long range transport beyond pretty pictures? Work by Kaufman 2006, Yu 2008 MODIS seeing pollution from China spilled over NW Pacific on Jan. 1, Yoram Kaufman s formula: τ a = ( fτ fd ) τ ( fm fd ( fa fd ) ) τ m Whereτ, τ a and τ m are total, anthropogenic, and maritime aerosol optical thickness Anthropogenic AOD MODIS f τ, f d, f m, f a are fractions of fine mode, dust, maritime, and anthropogenic aerosol optical thicknesses τ a is derived using a modified/ improved Kaufman method Using vertical information from GLAS and CALIPSO, RH data from AIRS, and mass Anthropogenic (pollution+smoke) AOD from: Hongbin extinction Yu (Yu et efficiency al., JGR 2008) from field measurements to

6 Measurement-based estimate of transpacific transport of anthropogenic aerosols It is estimated that ~ 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 Export Import From: Hongbin Yu (Yu et al.,

7 The column amount is informative, but: The impact on air quality depends on vertical extent vertical profile is the key The impact on precipitation depends largely on aerosol absorption single scattering albedo is the key We use a global model GOCART to estimate these quantities

8 A. Implications for regional air quality Composition and origins of surface fine mode particulate matter (PM) over the US Comparing model results with data from the IMRPOVE network over the US Attributing origin of the surface fine PM Intercontinental transport from one region to another

9 Emissions in 2001 Sulfur emission from pollution sources (TgS/yr): World 64.9 Asia 26.3 Europe 17.3 North America 12.3 (3 regions emit 85% of global total pollution) Dust emissions (Tg/yr): World 2773 Eastern Asia 566 Middle East 443 Northern Africa 1609 (3 regions emit >90% of global total)

10 IMPROVE: 135 sites in the U.S. in 2001 IMPROVE (Interagency Monitoring for Protected Visual Environments) program: Initiated in 1985 by EPA, NPS, USDA, etc. Measuring sulfate, nitrate, ammonia, BC, OC, salt, mineral elements, and many other species Reporting PM2.5, PM10, and RCFM (reconstructed

11 Overall comparison (mon avg, all sites): R B S Sulfate BC OC Fine dust RCFM R: correlation coefficient; B: relative bias; S: skill score Sulfate: agree the best OC & BC: model lower Dust: model higher RCFM: OK (error cancellation?) The largest data uncertainties are also in OC, BC, and dust! Bottom line: we may overestimate the amount from outside

12 Composition averaged over IMPROVE sites: Western US Eastern US

13 Origin of the fine PM over the US: North America n polluti on

14 Origin of the fine PM over the US: North America n polluti on + biomass burning

15 Origin of the fine PM over the US: North America n polluti on + biomass burning + biogeni c

16 Origin of the fine PM over the US: North America n polluti on + biomass burning + biogeni c + local fine dust [= Total local RCFM]

17 Origin of the fine PM over the US: North America n polluti on + biomass burning + biogeni c + local fine dust + Importe d dust

18 Origin of the fine PM over the US: North America n polluti on + biomass burning + biogeni c + local fine dust + importe d dust + importe d polluti Fine PM origin: North America pollution (NAM): Western 30-40% Eastern 65-70% Pollution import (TAP): Western 2-6% Eastern 2-4% Dust import (TDUf): Western 15-24% Eastern 7-9% Total import (TDUf+TAP): Western 20- Red: local pollution (may control) Other: 30%

19 Intercontinental transport of pollution (NH 4 ) 2 SO 4 as a surrogate Asian pollution: Eastward transport, efficient removal during transport µg m -3 to W. US and N. Africa, more to E. Africa and E. Europe < 10% contribution to other continents except Arctic European pollution: Pollution widely spread Largest impact on N. Africa! µg m -3 to E. Asia! North American pollution: Relatively regionalized Amount to N. Africa & Saudi = Amount from Asia to W.US

20 Intercontinental transport of fine dust Asia: Efficient eastward transport µg m -3 to US, N. Africa, Middle East, more to E. Africa and E. Europe 50% over Arctic Widespread in NH Middle East: Limited effects, mostly to neighbors Largest impact on N. Indian O µg m -3 to E. Asia! Africa: Westward to Central America, northward to Europe, eastward to Asia- Pacific- -North America!!

21 Leaving Asia Entering N. Am. Pollution plume height Asian pollution: Max in at surface leaving Asia Max above surface (1.5 2 km) entering North America Requiring downward mixing to send plume to North American surface European pollution: Contributing 10 50% in the Asian outflow! North American pollution: Already showing importance at the west coast

22 Leaving Asia Entering N. Am. Dust plume height Asia: Plume lifted leaving Asia, extending vertically Max 2 6 km entering North America Widespread in NH Africa: Contributing 10 50% of fine dust to the Asian outflow! Middle East: Contributing ~10% of fine dust to the Asian outflow!

23 Conclusions for part A Most fine PM at the surface of US are from North America only 2-6% fine PM from other continents pollution and 7-20% from other continents deserts (2001 scenario) European pollution has the largest impact potential to other continents because of the shorter traveling distance and predominant BL outflow Dust from Asia has the largest impact potential because of efficient transport There are significant fraction of European pollution and African dust in the so called Asian outflow

24 A few examples of comparisons with CALIPSO data on aerosol vertical distribution and aerosol type

25 Lidar ratio S a Comparison of lidar ratio S a (550 nm) values obtained from GOCART model and used in CALIOP retrieval Airmass category Polluted continental Biomass burning S a used by CALIOP S a (range) from GOCART GOCART type criteria (43 85) FF+BB > 2/3 τ; FF > BB (45 77) FF+BB > 2/3 τ; BB > FF Dust (31 52) DU > 1/2 τ Background Continental Marine (seasalt) (19 85) FF+BB 1/3 τ; DU 1/2 τ (19 25) SS > 2/3 τ Polluted dust Mixture -- Depending on composition None of the above

26 T ZN Pollution in Europe, heavy, vertically extended dust in Africa, smoke from S. Africa Aqua MODIS AOT GOCART AOT B A B A C C E D E D CALIOP extinction 532 nm GOCART extinction 532 nm Dust Pollut. Smoke Seasalt Lidar ratio: Indication of aerosol type CALIOP lidar ratio 532 nm GOCART lidar ratio 532 nm Dust Pollut. Smoke Seasalt

27 T ZN Dust cloud just off the west coast of northern Africa Aqua MODIS AOT GOCART AOT B A B A C C E D E D CALIOP extinction 532 nm GOCART extinction 532 nm Dust Lidar ratio: Indication of aerosol type CALIOP lidar ratio 532 nm GOCART lidar ratio 532 nm Dust

28 T ZN Aerosols at two sides of Himalaya: Dust in China and pollution in India Aqua MODIS AOT GOCART AOT A B B C C D D A E E CALIOP extinction 532 nm GOCART extinction 532 nm Dust Pollution Seasalt Lidar ratio: Indication of aerosol type CALIOP lidar ratio 532 nm GOCART lidar ratio 532 nm Dust Pollution Seasalt

29 T ZN High altitude sulfate over Siberia, smoke plumes from SE Asia Aqua MODIS AOT A GOCART AOT A B B C C D D E E CALIOP extinction 532 nm GOCART extinction 532 nm Sulfate/Dust Pollution/Dust Smoke Seasalt Lidar ratio: Indication of aerosol type CALIOP lidar ratio 532 nm GOCART lidar ratio 532 nm Sulfate/Dust Smoke Pollution/Dust Seasalt

30 T ZN Thick volcanic plume over near Alaska, elevated dust plume transported from Australia Aqua MODIS AOT GOCART AOT A A B B C C D D E E CALIOP extinction 532 nm GOCART extinction 532 nm Sulfate Dust Seasalt Seasalt Lidar ratio: Indication of aerosol type CALIOP lidar ratio 532 nm GOCART lidar ratio 532 nm Sulfate Dust Seasalt Seasalt