Atmospheric Chemistry and Air Quality S. Lal Physical Research Laboratory, Ahmedabad

Transcription

1 Atmospheric Chemistry and Air Quality S. Lal Physical Research Laboratory, Ahmedabad TERI University, New Delhi 28 Nov. 2011

2 Anthropogenic Emissions of Pollutants Emissions of air pollutants in Gg (Tg for CO 2 only) during 2000 Country SO 2 NO x CO 2 CO CH 4 NMHCs China 20,385 11,347 3, ,749 38,356 17,432 Japan 801 2,198 1,203 6,806 1,143 1,920 Indonesia 884 1, ,105 6,443 6,903 India 5,536 4,591 1,886 63,340 32,851 10,844 Asia Total 34,316 26,768 9, , ,821 52,150 America 16,498 25,038 5,840 94,033 61,450 17,907 Europe 33,337 15,603 4,642 85,424 34,195 20,750 Streets et al. 2003, JGR

3 Increasing anthropogenic emissions GOME satellite Akimoto (2003), Science NOx emissions during (Gg NO 2 /yr) China India Industrial & power plants : 45% Transportation sector : 37% Biomass burning : 18% Streets et al. 2003, JGR

4 Trends in Column NO 2 over India Annual growth rates from 1996 to 2006 Delhi (28.5N, 77.2E) 11.3% Ahmedabad (23N, 72.5E) 10.0 % Pune (18.5N, 73.8E) 1.5% Bangalore (12.9N, 77.6E) 3.5% VS, SL et al., AE 2010

5 Oil and Coal usage in India Annual increase rates : 3-5%

6 Chemistry-Climate Interactions Sun Temperature Composition & Chemistry Dynamics Emissions Major Questions : How do anthropogenic emissions of gaseous and particulate matter in the atmosphere affect climate change? How does climate change affect air quality?

7 Temperature Trends in India All India Surface temperature and Kothawale and Kumar, GRL 2005 Mallik and Lal, CS 2011

8 Ozone in the atmosphere Stratosphere O 2 +UV Sunlight = O+O O 2 +O+M = O 3 +M Ozone characteristics: Good ozone: Stratospheric ozone The ozone layer ~85% ~15% Troposphere Precursors +NOx +Visible Sunlight = O 3 Bad ozone: Tropospheric ozone Smog

9 Tropospheric Ozone Production Balance Loss CO OH H CO2 H O2 M HO2 M HO 2+NO NO 2+OH 420nm NO2 hv NO O O O2 M O3 M CO 2O CO O 420nm O 3 + h O( 1 D) + O 2 HO + O 3 HO 2 + O 2 HO 2 + O 3 OH + 2O 2 NO + O 3 NO 2 + O 2 Dry Deposition Similar set of reactions for CH 4 and NMHCs Chameides

10 Diurnal variations in Ozone and Related Gases

11 Non Methane Hydrocarbons (NMHCs) and Volatile Organic Compounds VOCs These play key role in the formation of ozone and oxidation process in the atmosphere. Ratio = Amd/Mt. Abu Local emission of various NMHCs plays very important role at Ahmedabad while at Mt. Abu transport from the source regions is a key parameter in their distributions.

12 Seasonal variations in trace gases at Ahmedabad, India Monthly mean data Monthly mean Sum of C 2 -C 5 NMHC species, UV-B flux, ozone and CO during different months of the year 2002 at Ahmedabad. Vertical bars are 1 variation.

13 Tropospheric ozone Longterm Trends Global Ahmedabad Average ozone mixing ratio increased from 14.7 ppbv during to 25.3 ppbv during , resulting in a linear increase of ~ 1.4%/year Naja and Lal, GRL, 1996

14 The Indo-Gangetic Plain AOD at 550 nm from MODIS/Terra CO distribution using the 3D photochemical model of MPIM, Hamburg for a winter month

15 ISRO GBP Land Campaigns I & II, Feb and Dec Hissar Nainital New Delhi Agra Shadnagar/Hyderabad Kanpur Allahabad Jaduguda Kharagpur

16

17 Trace gases at Hissar- Dec High variability in all agses. O3- Large diurnal amplitude. CO-Often exceeding 1 ppm level. NOx- Often exceeding 20 ppb. Effect of fog observed. Date

18 CO-NOx Relation CO/NOx AHMEDABAD HISAR KANPUR CHINA US EUROPE Japan The slope ( CO/ NOx) is related to primary emission sources of these species. In high temperature combustion processes (e.g., use of fossil fuel in vehicles and power plants) these slope values are lower than those emitted from biofuel and biomass burning These results indicate that emission from biofuel combustion and biomass burning play major role in the observed distributions of various trace gases in India.

19 Vertical distribution of ozone over Ahmedabad- based on ozonesondes measurements from Ahmedabad 50 Latitude Africa/ Europe (March) Longitude Marine region (July) WI Region (October) Effects of : Regional Pollution - Spring and summer seasons Longrange Transport Spring season in the free troposphere Marine - Monsoon season in the BL

20 Ozone at Mt. Abu (24.6N, 72.7E) and Nainital (29.4N,79.4E) Maximum ozone : Mt. Abu - Autumn/Winter Nainital - Spring/Summer Average Ozone (ppbv) Hourly Average (NTL ) Hourly Average (NTL ) Hourly Average (NTL ) Nainital Nainital Nainital Monhtly Average (Mt Abu) Model derived contributions (in ppbv) for Nainital Startospheric Ozone European Emissions South Asia Emissions Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mt Abu Observatory in the early 1990 s Variations and levels of ozone and related trace gases are different over different parts of India suggesting diverse regional emission sources Kumar et al., JGR, 2010

21 Transport of Pollutants NASA/TOMS Smoke

22 Ozone over marine regions using balloon sondes A typical set of profiles

23 Intrusion of land plume over North Bay of Bengal (N-BoB) and North Arabian Sea (N-AS)- ICARB 2006 N-BoB S-BoB NBoB - SBoB N-AS S-AS NAS SAS Potential Source Contribution Function (PSCF) analysis Transport of ozone rich layer (60-90 ppbv) over N-BoB attributed to advection of air from Indo-Gangetic Plain. Srivastava et al., JGR 2011

24 Comparison of measurements over BOB, AS and IO

25 Past and future changes in global tropospheric ozone 1850 to 1990 (July) NH Mid lat : BL 80% (15 ppb) FT 40-70% (20-40 ppb) O 3 RF Global avg 0.43 W/m 2 June - Aug 0.3 W/m 2 Dec.-Feb to 2050 IPCC scenario IS92a medium case CO : 1.7 fold increase NOx : 2.1 fold increase NMHCs : 2.4 fold increase Large (3-7 fold) changes in SE Asia and Africa (>30% or 4 ppb at surface) O 3 RF 0.3 W/m 2 June-Aug 0.2 W/m 2 Dec.-Feb. Brasseur et al., GRL 1998

26 Focus of tropospheric research on chemistry-climate interactions over the Asian region Understanding the processes that connect emissions (source precursors) to abundances and abundances to the climate forcings are essential for an accurate prediction of the future climate and an assessment of the impact of climate change and variations on the earth system. Prather et al JGR 2003 SPARC-IGAC Stratospheric Processes and their Role in the Climate

27 Effects of ozone on human health Shortness of breath, dry cough or pain when taking a deep breath, tightness of the chest, wheezing, and sometimes even nausea are common responses to ozone. Ozone reacts with molecules in the lining of our airways. Chemical bonds break and reform in different ways with the addition of oxygen atoms (the process of oxidation) from ozone, and this causes acute inflammation. The lining of our airways loses some of its ability to serve as a protective barrier to microbes, toxic chemicals, and allergens. Breathing becomes more difficult. Respiration

28 Impact of ozone on crop yields Many farmers are unaware that ozone is reducing their yields. Ozone enters the plant s leaves through its gas exchange pores (stomata), just as other atmospheric gases do in normal gas exchange. It dissolves in the water within the plant and reacts with other chemicals, causing a variety of problems. Chameides et al, 1999; Krupa et al, 2001

29 Chemistry- Aerosol-Cloud Interactions Radiation Size distribution of aerosols Size segregated chemical composition Gases (SO2, NOx, VOCs) Cloud properties T, RH

30 Measurements of ozone and related trace gases in different regions : A network of environmental observatories in India under ISRO GBP Nainital 29.4N,79.4E ~2.0 km Kullu Nainital Agra Kanpur Mt. Abu Ahmedabad Nagpur Kolkata Bhubneshwar Shillong Mt. Abu 24.6N,72.6E ~1.7 km Vishakhapatnam Hyderabad Anantpur Gadanki Thalassery Ooty Thumba Port Blair Ooty 11.4N,76.7E ~ 2.5 km Mt Abu Observatory in the early 1990 s

31 Scope India is a rapidly industrializing country in the developing Asia. The ever increasing demand for energy results in increased emissions of various pollutants both gaseous as well as particulates. Many trace gases other than CO 2 also contribute significantly to global warming, alter the chemistry of the atmosphere and their higher levels affect the biosphere, human health as well as crop yields. The lower atmosphere is highly influenced by local emissions as well as transport. The air quality and the chemistry of the atmosphere are changing. The climate is also affected by chemical changes in the atmosphere. Hence, there is a need to make long-term measurements of various atmospheric parameters (GHGs, trace gases, aerosols and meteorological parameters) from many sites in India representing different eco-systems.

32 Future Needs Chemistry and air quality Insitu measurements (trace gases, aerosols, black carbon, dust, radiation etc) in the free troposphere to quantify chemical changes and associated radiative changes. Focus on Indo Gangetic Plain. Budgets and Emission inventories Sources and Sinks of GHGs Ocean, land and atmosphere. There is a need to make emission inventories of trace gases for the Indian and Asian region. These are needed for chemical models. Prediction of future changes Atmospheric Chemistry Modeling to understand observations, atmospheric processes and to predict future changes.

33 I thank you for your attention

34 Non Methane Hydrocarbons (NMHCs) NMHC concentration ratios provide useful indicators of tropospheric oxidation and transport processes. However, the influences of both photochemical and mixing processes are inextricably linked in the evolution of these ratios.

35 Petroleum and Coal Consumption in India Petroleum Coal Year Thousands of Barrels Million Tons per day per year Annual Inc 3-5%/yr ~ 3% * 1 Barrel = 159 lit