1 Source receptor reconciliation of INDOEX aerosolsChandra Venkataraman Department of Chemical Engineering Indian Institute of Technology, Bombay, India Collaborators: Shubha Verma - IIT Bombay, India Gazala Habib – University of Illinois, Urbana Champaign Manish Shrivastava – Carnegie Mellon University, USA M. Shekar Reddy – NOAA-GFDL, Princeton, USA Olivier Boucher – MetOffice, UK Arantza Fernandez, Toni Miguel, Sheldon Friedlander– UCLA, USA Tami Bond – UIUC, USA

2 South Asian region Population (billions):Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka Population (billions): 2000 : 1.2 (27%) about 1/5 of world 2025 : 2.0 (40%) about 1/4 of world % Urban Population

3 Indian Ocean Experiment: 1996-1999Findings High concentrations of aerosols over the ocean in the boundary layer and at altitudes of 1-3 km. Large atmospheric heating rate of +20 W m-2 Large surface cooling rate of –30 W m-2 For reference: global mean greenhouse gas atmospheric heating = +2.5 Wm-2

4 INDOEX-IFP, 1999 Species contribution to PM2.5 at KCO (5N, 73.5 E) during Feb , 1999 500 nm 1996 1997 1998 1999 Sulfate = 40% (FF) Organics = 26% (FF/BB/NAT) BC = 14% (FF) Large inter-annual variations in AOD modulated by emissions/ regional meteorology Ramanathan et al., 2002, UNEP

5 1999 – anomalous forest firesAverage number of fires (arbitrary units) INDOEX IFP 99 3 – fold 2 – fold ATSR Forest Fire counts

6 India fuel consumptionFossil: 9,411 PJ (1 PJ = 1015 J) Biofuel: 8,213 PJ (~380 Tg) Biofuels / biomass (Gg) Fuelwood Dung-cake Crop waste Crop waste open burning Forest fire 278 63 37 116 35 6% 11% 47% 29% 7% (Tg)

7 Aerosol emissions from residential biofuelsStove fuel system used  Traditional single pot mud stove 5-wood species, animal dung and 10-crop waste types Dilution sampler Optimized for aerosol stabilization Mass of fuel, duct velocity, temperatures in combustion zone, duct and plenum recorded each minute Pollutant measurement PM2.5: Cyclone sampler. OC-EC: Thermal optical transmittance (S. California Particle Centre and Supersite). SO2, NO2, ions, trace elements and absorption (U Wisc, Madison, UIUC). Dilution sampler Burn cycle Equilibration cylinder Cyclone outlet pipe Filter holders AIHL Cyclone Inlet for air Connection to Pump Critical Orifices for flow control Venkataraman et al. Science, 2005, 307, Habib et al., in preparation, 2005. Aerosol sampler

8 Burn rate >100 kgh-1 2-9 kgh-1 High burn rate = 2 kg h-1 Low burn rate = 0.9 kg h-1 All these figures shows the minimum, average (the middle line) and maximum values of parameters

9 Chemical composition of PM2.5 from biofuel combustionHigh burn rate = 2 kg h-1 Low burn rate = 0.9 kg h-1

10 INDOEX atmospheric aerosol:OC/EC ratio INDOEX atmospheric aerosol: 0.9 ( )

11 Size Distributions

12 Burn rate and PM emissions

13 Burn rate and PM composition and size

14 Mass absorption cross-sectionINDOEX atmospheric aerosol: 1.1 ( ) m2(gPM)-1 Integrating plate method – Tami Bond, UIUC

15 Why are biofuel aerosols strongly absorbing?EC content not through origin

16 Why are biofuel aerosols strongly absorbing? Organic constituentsAbsorbing organics ? (m2 gEC-1)

17 Why are biofuel aerosols strongly absorbing?Size / hygroscopicity Fossil fuel aerosols Biofuel aerosols dp <  dp >>  absorption by enhanced diffraction optical focussing BC core alone at edge of shell by shell f (RH, t)

18 Size / shell effects

19 Black carbon: Residential fuelFuelwood: 281x103 (Ggy-1) (Ggy-1) Crop waste Black carbon: 174 (Ggy-1) (Ggy-1) Wood Dried cattle manure Kerosene LPG 0.34% 2% 17% 81%

20 Black carbon: Industrial fossil fuelBC: 90 Gg y-1 kg km-2 y-1

21 Seasonal, interannual variability – MODIS firesCropland fire Forest fire Very dense forest (IGBP 1-5) Open and dense forest (IGBP 6-9) Cropland (IGBP 12, 14) Jan01 Apr01 Jul01 Oct01 Jan02 Jan03 Jan04 Months/Years

22 Black carbon: Forest burningBC: 18 Ggy-1 kg km-2 month-1

23 Black carbon: Crop waste field burningBC: 86 Ggy-1 kg km-2 month-1

24 India emissions inventoryBiofuels Fossil fuel Forest burning Crop waste open burning BC=400 Ggyr IOM=1760 Ggyr CO2=1915x103 Ggyr-1 OC=1170 Ggyr PM2.5=4320 Ggyr CO=65x103 Ggyr-1 OM=2160 Ggyr SO2=4175 Ggyr-1 Pollutants IOM BC OC OM PM2.5 CO2 CO SO2 Relative contribution (%) of sources to pollutant emissions Reddy and Venkataraman, 2002a, b, Atmos Environ; Habib et al., 2004, GBC; Venkataraman et al., 2005a, Science; 2005b GBC.

25 Simulations of aerosol transport during the INDOEX-IFP in the LMD-ZTIntroduction of multi-component aerosols: sulphate, black carbon, organic matter, fly-ash, dust (<1µm; 1-10µm) and sea-salt (8 size bins). India emissions at 0.25ox0.25o with ground level and elevated sources (MSR/CV 2002a, b). Asia emissions (Streets et al. 2003). Nudged to ECMWF winds from Nov 1998 to March 1999. Parameterisation for carbonaceous aerosol growth from hydrophobic to hydrophilic state. Wavelength dependent aerosol optical properties at different relative humidity. Zoom to 0.47 x 0.47 deg resolution over INDOEX domain and 19 vertical layers or high resolution with 50 vertical layers. Reddy et al., 2004, JGR; Verma et al., 2005, JGR.

26 Spatial variability of chemical speciesSulphate BC Ron Brown cruise track Organic matter Fly-ash Sea-salt

27 AOD at continental and ocean stations

28 Aerosol optical depth: METEOSAT versus model

29 Questions Surface concentrations and column loading: which species dominate? Geographical origin of INDOEX aerosols: proximate sources or long-range transport? Sources of anthropogenic aerosols: biofuel, open burning, fossil fuels or natural?

30 Surface aerosol species distributions

31 Which species dominate optical depth?Sulphate contribution to AOD (%) 50 40 30 20 10 1 Organic matter contribution to AOD (%)

32 Role of Fly-ash Surface concentration (μg m-3)Annual emissions are about 1.5 Tg yr-1 from India, predominantly from coal-based power plants. % Contribution to visible AOD during Jan.-Mar. Surface concentration (μg m-3)

33 South Asia contribution - sulphateSurface Concentration AOD

34 South Asia contribution - carbonBlack carbon Organic matter Surface Conc AOD

35 Inflow of carbonaceous aerosolsOrganic matter isosurface – 2 g m-3

36 Modelling with region and source tagged emissionsSource regions Receptor regions ROW IGP NWI India EA AFWA AS BOB SEA CNI SI TIO2 TIO1

37 Regional contribution to total carbon TC surface concentrationsIGP CNI AFWA 100 90 80 70 60 50 40 30 20 10

38 Regional contribution to total carbon TC-AODIGP CNI AFWA 100 90 80 70 60 50 40 30 20 10

39 Domain averaged contribution to receptor regions: Surface concentrations

40 Domain averaged contribution to receptorregions: AOD at 550 nm

41 Domain averaged contribution to receptor regions:Species AOD at 550 nm

42 Regional contribution to dust AODNWI EA AFWA 100 90 80 70 60 50 40 30 20 10

43 Domain averaged source contribution to receptor regions: Surface concentrations

44 Domain averaged source contribution to receptor regions: AOD at 550 nm

45 Domain averaged source contribution toreceptor regions: Species AOD at 550 nm

46 Some answers Chemical and optical characteristics of biofuel combustion aerosols indicate significant impact on regional aerosol loadings. Carbonaceous aerosols dominate regional aerosol loading, followed by sulphate and fly-ash. SAARC emissions dominate regional sulphate. Are an important but not dominant source of regional carbon. Africa-West Asia significant contributor to carbonaceous aerosols and dust over AS, TIO and the Indian subcontinent. Indo-Gangetic plain important contributor to Bay of Bengal, India and long range transported aerosols over KCO. Fossil fuels and biofuels contribute to total aerosols – all species. Model under-estimation of BC may underestimate biofuel/biomass contribution. BC from biofuels-S. Asia, OM from open burning-Africa-West Asia, sulphate from fossil fuels-S. Asia.

47 Future directions On-road vehicular emission factors, aerosol surface growth from water uptake, optical parameterisation for biofuel aerosol. Linking anthropogenic aerosols to economic sectors / sources and assessment of technology substitution. Effects of inter-continental transport on Indian region air quality and climate. Strategies to leverage climate benefits from regional air resources management.