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AREP GAW Section 9 Pollutant Lifecycles and Trends Definitions and Importance Multi-year (Long-term) Trends Seasonal Trends Short-term Changes.

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Presentation on theme: "AREP GAW Section 9 Pollutant Lifecycles and Trends Definitions and Importance Multi-year (Long-term) Trends Seasonal Trends Short-term Changes."— Presentation transcript:

1 AREP GAW Section 9 Pollutant Lifecycles and Trends Definitions and Importance Multi-year (Long-term) Trends Seasonal Trends Short-term Changes

2 AREP GAW THE ATMOSPHERE: OXIDIZING MEDIUM IN GLOBAL BIOGEOCHEMICAL CYCLES EARTH SURFACE Emission Reduced gas Oxidized gas/ aerosol Oxidation Uptake Reduction

3 AREP GAW Section 9 – Pollutant Lifecycles and Trends 3 Definitions and Importance Definitions –Trends are longer-term (multi-year) changes in air pollution caused by population and emissions changes –Lifecycles are daily and episodic changes in pollution levels –Episodes are several day events when air quality concentrations are high Importance to forecasting –Determining how emissions changes affect air quality –Knowing which pollutants occur in each season –Understanding typical day-to-day changes Three time periods –Long-term trends –Seasonal trends –Short-term lifecycles Day/night (diurnal) Day of week Multi-day

4 AREP GAW Section 9 – Pollutant Lifecycles and Trends 4 Multi-year Trends Multi-year trends – Five or more years Affected by –Emissions changes As emissions controls occur, pollutant levels typically decrease Similar weather conditions may not produce the same pollutant concentrations –Year-to-year weather changes Multi-year climate changes For example, above normal temperatures typically result in above normal ozone concentrations –Monitor environment changes (location, environment) If monitors move or the environment around monitors changes, the resulting air quality conditions will be affected –Metric used to evaluate trends can affect trend results Maximum (peak) concentration 90 th percentile 4 th highest value Days above a threshold

5 AREP GAW Section 9 – Pollutant Lifecycles and Trends 5

6 AREP GAW Section 9 – Pollutant Lifecycles and Trends 6 Increase is important from pollution and climate perspectives

7 AREP GAW Section 9 – Pollutant Lifecycles and Trends 7 Multi-year Trends Example (1 of 3) Long-term ozone trends in Los Angeles, California, USA

8 AREP GAW Section 9 – Pollutant Lifecycles and Trends 8 Multi-year Trends Example (2 of 3) Number of days with daily maximum 1-hour O 3 > 0.10 ppm at any one site in each capital city of Australia, 1991–2001

9 AREP GAW Section 9 – Pollutant Lifecycles and Trends 9 Seasonal Trends Affected by –Season (temperature, precipitation, clouds) Unusual weather conditions may affect severity of episodes For example, above normal temperatures typically result in above normal ozone concentrations –Emissions changes (substantial) Reformulated fuel Changes in industrial emissions Other Useful to understand typical season for each air pollutant –Determines forecasting season

10 AREP GAW Section 9 – Pollutant Lifecycles and Trends 10 GLOBAL DISTRIBUTION OF CO NOAA/CMDL surface air measurements

11 AREP GAW Section 9 – Pollutant Lifecycles and Trends 11 O 3 at the surface Surface sites in industrialized regions show an even more pronounced summer-time peak Seasonal cycle of O 3 concentrations at the surface for different rural locations in the United States. From Logan, J. Geophys. Res., , 1999.

12 AREP GAW Section 9 – Pollutant Lifecycles and Trends 12 Seasonal Trends Example (1 of 5) Compare ozone vs. temperature departure from normal Columbus, Ohio, USA Daily 8-hr ozone concentration (AQI) Temperature departure –Daily maximum temperature – daily normal temperature Number of high ozone days Unhealthy for Sensitive Groups on the AQI scale 9286 Number of days with above normal temperature

13 AREP GAW Section 9 – Pollutant Lifecycles and Trends 13 Seasonal Trends Example (2 of 5) Temperature departure from normal vs. maximum ozone AQI AQI Temperature above normal (64) Temperature below normal Unhealthy for SG (9) Moderate 2001

14 AREP GAW Section 9 – Pollutant Lifecycles and Trends 14 Seasonal Trends Example (3 of 5) Temperature departure from normal vs. maximum ozone AQI Unhealthy for SG (24) Moderate Temperature above normal (93) Temperature below normal Unhealthy (4) 2002 AQI

15 AREP GAW Section 9 – Pollutant Lifecycles and Trends 15 Seasonal Trends Example (4 of 5) Temperature departure from normal vs. maximum ozone AQI AQI Unhealthy for SG (4) Moderate Temperature above normal (40) Temperature below normal Unhealthy (2) 2003

16 AREP GAW Section 9 – Pollutant Lifecycles and Trends 16 Seasonal Trends Example (5 of 5) Days above Air Pollution Index (API) in Shanghai, China, from

17 AREP GAW Section 9 – Pollutant Lifecycles and Trends 17 Short-Term Lifecycles Largely controlled by weather conditions and emissions events that are predicable Affected by –Weather conditions Sunlight Winds Dispersion Other factors –Large emissions changes Fires Non-routine emissions events (holidays, etc.) Day-of-week emissions changes

18 AREP GAW Section 9 – Pollutant Lifecycles and Trends 18 Net Ozone Net Production Peak Destruction Precursor Accumulation Emissions Dispersion Vertical mixing Sunlight Transport Removal Short-Term Changes – Example (1 of 9) Hour (LT)

19 AREP GAW Section 9 – Pollutant Lifecycles and Trends 19 Short-Term Changes – Example (2 of 9) Key diurnal factors

20 AREP GAW Section 9 – Pollutant Lifecycles and Trends 20 Short-Term Changes – Example (3 of 9) Diurnal Pattern Categories

21 AREP GAW Section 9 – Pollutant Lifecycles and Trends 21 Short-Term Changes – Example (5 of 9) Diurnal Pattern Categories

22 AREP GAW Section 9 – Pollutant Lifecycles and Trends 22 Short-Term Changes – Example (6 of 9) Diurnal Pattern Categories

23 AREP GAW Section 9 – Pollutant Lifecycles and Trends 23 Multi-day time series for model predictions at surface sites. Figure. Comparison of model performance in surface sites, NEI 1999 and NEI 2001

24 AREP GAW Section 9 – Pollutant Lifecycles and Trends 24 Lifecycles – Multi-day Combined ozone and PM 2.5

25 AREP GAW Section 9 – Pollutant Lifecycles and Trends 25 PM 2.5 Variation in Beijing

26 AREP GAW Section 9 – Pollutant Lifecycles and Trends 26 Temperature Dewpoint Wind Speed PM 2.5 variation with:

27 AREP GAW Section 9 – Pollutant Lifecycles and Trends 27 Build-up of regional PM 2.5

28 AREP GAW Section 9 – Pollutant Lifecycles and Trends 28 Sulfur-to- Aluminum Ratio Ratio of PM2.5 to PM10

29 AREP GAW Section 9 – Pollutant Lifecycles and Trends 29 Summary Trends and lifecycle of pollution Long-term – Controlled by changes in emissions and climate Seasonal – Controlled by annual and seasonal weather patterns Short-term – Controlled by weather and non-routine emissions events

30 AREP GAW Section 9 – Pollutant Lifecycles and Trends 30 Short-Term Changes – Example (7 of 9) GTT – Please provide examples showing the influence of weather, emissions, and chemistry

31 AREP GAW Section 9 – Pollutant Lifecycles and Trends 31 Short-Term Changes – Example (8 of 9) GTT – Please provide examples showing day of week influence on pollution

32 AREP GAW Section 9 – Pollutant Lifecycles and Trends 32 Short-Term Changes – Example (9 of 9) GTT - Show multi-day lifecycle of an episode

33 AREP GAW Section 9 – Pollutant Lifecycles and Trends 33 Multi-year Trends Example (3 of 3) Ozone trends with and without adjusting for meteorology The top left panel shows the raw ozone season values while the top right panel shows the seasonal values adjusted for meteorology. Values on the y-axis are on a log scale with the mean removed. The bottom two panels are just smooth splines fit to the data in the top two panels. The plots also include +/- twice the standard error of prediction. (Courtesy: Bill Cox, U.S. EPA)

34 AREP GAW Section 9 – Pollutant Lifecycles and Trends 34 PEROXYACETYLNITRATE (PAN) AS RESERVOIR FOR LONG- RANGE TRANSPORT OF NO x

35 AREP GAW Section 9 – Pollutant Lifecycles and Trends 35 WindsClouds, fogWindsTemperature PrecipitationRelative humidity Solar radiationRelative humidityWinds Vertical mixingSolar radiation condensation and coagulation photochemical production cloud/fog processes gases condense onto particles cloud/fog processes Measurement Issues Inlet cut points Vaporization of nitrate, H 2 O, VOCs Adsorption of VOCs Absorption of H 2 O transport sedimentation (dry deposition) wet deposition Mechanical Sea salt Dust Combustion Motor vehicles Industrial Fires Other gaseous Biogenic Anthropogenic Particles NaCl Crustal Particles Soot Metals OC Gases NO x SO 2 VOCs NH 3 Gases VOCs NH 3 NO x Sources Sample Collection PM Transport/Loss PM Formation Emissions Chemical Processes Meteorological Processes Particulate Matter Chemistry (4 of 4)

36 AREP GAW Section 9 – Pollutant Lifecycles and Trends 36 WindsClouds, fogWindsTemperature PrecipitationRelative humidity Solar radiationRelative humidityWinds Vertical mixingSolar radiation condensation and coagulation photochemical production cloud/fog processes gases condense onto particles cloud/fog processes Measurement Issues Inlet cut points Vaporization of nitrate, H 2 O, VOCs Adsorption of VOCs Absorption of H 2 O transport sedimentation (dry deposition) wet deposition Mechanical Sea salt Dust Combustion Motor vehicles Industrial Fires Other gaseous Biogenic Anthropogenic Particles NaCl Crustal Particles Soot Metals OC Gases NO x SO 2 VOCs NH 3 Gases VOCs NH 3 NO x Sources Sample Collection PM Transport/Loss PM Formation Emissions Chemical Processes Meteorological Processes Particulate Matter Chemistry (4 of 4)

37 AREP GAW Section 9 – Pollutant Lifecycles and Trends 37 PhenomenaEmissionsPM FormationPM Transport/Loss Aloft Pressure Pattern No direct impact. Ridges tend to produce conditions conducive for accumulation of PM 2.5. Troughs tend to produce conditions conducive for dispersion and removal of PM and ozone. In mountain-valley regions, strong wintertime inversions and high PM 2.5 levels may not be altered by weak troughs. High PM 2.5 concentrations often occur during the approach of a trough from the west. Winds and Transport No direct impact.In general, stronger winds disperse pollutants, resulting in a less ideal mixture of pollutants for chemical reactions that produce PM 2.5. Strong surface winds tend to disperse PM 2.5 regardless of season. Strong winds can create dust which can increase PM 2.5 concentrations. Temperature Inversions No direct impact.Inversions reduce vertical mixing and therefore increase chemical concentrations of precursors. Higher concentrations of precursors can produce faster, more efficient chemical reactions that produce PM 2.5. A strong inversion acts to limit vertical mixing allowing for the accumulation of PM 2.5. RainNo direct impact.Rain can remove precursors of PM 2.5. Rain can remove PM 2.5. MoistureNo direct impact.Moisture acts to increase the production of secondary PM 2.5 including sulfates and nitrates. No direct impact. TemperatureWarm temperatures are associated with increased evaporative, biogenic, and power plant emissions, which act to increase PM 2.5. Cold temperatures can also indirectly influence PM 2.5 concentrations (i.e., home heating on winter nights). Photochemical reaction rates increase with temperature. Although warm surface temperatures are generally associated with poor air quality conditions, very warm temperatures can increase vertical mixing and dispersion of pollutants. Warm temperatures may volatize Nitrates from a solid to a gas. Very cold surface temperatures during the winter may produce strong surface-based inversions that confine pollutants to a shallow layer. Clouds/FogNo direct impact.Water droplets can enhance the formation of secondary PM 2.5. Clouds can limit photochemistry, which limits photochemical production. Convective clouds are an indication of strong vertical mixing, which disperses pollutants. SeasonForest fires, wood burning, agriculture burning, field tilling, windblown dust, road dust, and construction vary by season. The sun angle changes with season, which changes the amount of solar radiation available for photochemistry. No direct impact. Particulate Matter Meteorology How weather affects PM emissions, formation, and transport

38 AREP GAW Section 9 – Pollutant Lifecycles and Trends 38 ORIGIN OF THE ATMOSPHERIC AEROSOL Soil dust Sea salt Aerosol: dispersed condensed matter suspended in a gas Size range: m (molecular cluster) to 100 m (small raindrop) Environmental importance: health (respiration), visibility, radiative balance, cloud formation, heterogeneous reactions, delivery of nutrients…

39 AREP GAW Section 9 – Pollutant Lifecycles and Trends 39 PEROXYACETYLNITRATE (PAN) AS RESERVOIR FOR LONG- RANGE TRANSPORT OF NO x

40 AREP GAW Section 9 – Pollutant Lifecycles and Trends 40 Lifetimes of ROGs Against Chemical Loss in Urban Air Table 4.3 ROG SpeciesPhot.OHHO 2 ONO 3 O 3 n-Butane---22 h1000 y18 y29 d650 y trans-2-butene---52 m4 y6.3 d4 m17 m Acetylene---3 d y d Formaldehyde7 h6 h1.8 h2.5 y2 d3200 y Acetone23 d9.6 d Ethanol---19 h Toluene---9 h--- 6 y33 d200 d Isoprene---34 m---4 d5 m4.6 h

41 AREP GAW Section 9 – Pollutant Lifecycles and Trends 41 Impacts of NO x emission by mass, most NO x is emitted at the surface chemical impacts of NO x very non-linear –limited impact in the continental PBL high OH and high NO 2 /NO ratio near surface result in a short photo-chemical lifetime NO x concentrations are already substantial –per molecule, impact of NO x much greater in free troposphere venting to the free troposphere important emissions that occur in free troposphere –aircraft, lightning

42 AREP GAW Section 9 – Pollutant Lifecycles and Trends 42 Global tropospheric ozone Remote northern stations –spring-time maximum nearer to industrial emissions –broader maximum stretching through summer Seasonal cycle of O 3 concentrations at different pressure levels, derived from ozonesonde data at eight different stations in the northern hemisphere. From Logan, J. Geophys. Res., , 1999.

43 AREP GAW Section 9 – Pollutant Lifecycles and Trends 43 Global distribution constructed from surface observations, ozonesondes and a bit of intuition –note very low concentrations over tropical Pacific ocean Spatial distribution of climatological O 3 concentrations at 1000hPa. From Logan, J. Geophys. Res., , 1999.

44 AREP GAW Section 9 – Pollutant Lifecycles and Trends 44 Measurements from satellite Data from asd-www.larc.nasa.gov/TOR/data.html See Fishman et al., Atmos. Chem. Phys., 3, , –Tropospheric residual method total column (from TOMS) - stratospheric column (SBUV)

45 AREP GAW Section 9 – Pollutant Lifecycles and Trends 45 Midwest NY-MA-MD TX-NM Southeast Ohio etc California Canada 2km wind field A strong outflow event will appear from Saturday to Sunday Mission Overview July 1 to 25 Model CO

46 AREP GAW Section 9 – Pollutant Lifecycles and Trends 46

47 AREP GAW Section 9 – Pollutant Lifecycles and Trends 47 Aerosols in the East Asia Environment Have a Profound Impact on Resulting Secondary Pollution Formation Through Radiative Feedbacks

48 AREP GAW Climatology of observed ozone at 400 hPa in July from ozonesondes and MOZAIC aircraft (circles) and corresponding GEOS- CHEM model results for 1997 (contours). GEOS-CHEM tropospheric ozone columns for July GLOBAL DISTRIBUTION OF TROPOSPHERIC OZONE Li et al. [2001]

49 AREP GAW Section 9 – Pollutant Lifecycles and Trends 49 Short-Term Changes – Example (4 of 9) Diurnal Pattern Categories


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