Chapter 3: Observations 3 rd Meeting of Task Force on Hemispheric Transport of Air Pollution Coordinating Lead Authors: David Parrish, Hajime Akimoto (contributions from many) Presented by: Randall Martin, Dalhousie University Rich Scheffe, EPA

Acknowledge Contributors Hajime Akimoto, John Burrows, Russ Dickerson, David Edwards, Mat Evans, Shiro Hatakeyama, Tony Hollingsworth, Dan Jaffe, Gerard Jennings, Randall Martin, David Parrish, Joe Prospero, Lorraine Remer, Stuart Penkett, Ulrich Platt, Rich Scheffe, Akinori Takami, Kjetil Tørseth

Topics Background on Observations Satellite Perspective –Transport –Emissions In Situ –Ozone and its precursors –Aerosols –Surface Impacts –Trends Recommendations

Complementary Observations Independent evidence of transport Trends of background concentrations Evaluating and improving models Surface Monitors Column abundance (through Satellites) Modeling Field Campaigns

Major Nadir-viewing Space-based Measurements of Tropospheric Composition (Not Exhaustive) SensorTOMSGOMEMOPITTMISRMODISAIRSSCIA- MACHY TESOMIPARA- SOL CALIOPGOME-2IASI Platform (launch) multi (1979) ERS-2 (1995) Terra Aqua (1999) ( 2002) Envisat (2002) Aura (2004) PARA- SOL (2004) Calipso (2006) MetOp (2006) Equator Crossing mostly AM 10:30 10:30 1:3010:001:30 9:30 Typical Res (km) 38x38320 x40 22x2218x 18 10x1014x 18 60x305x8>24 x13 16x1840x4080x4012x 12 Global Obs (w/o clouds) ~ n/a OzoneXXXXXXX COXXXXX NO 2 XXXX HCHOXXXX AerosolXXXXXXXXX Solar Backscatter & Thermal Infrared

Satellite Perspective Long-Range Transport Emissions

Transport Evidence from Satellites: Ozone, CO and NO 2 Tropospheric NO 2 from SCIAMACHY for summer 2004 Martin et al., 2006 CO from MOPITT for July 2004 Pfister et al., 2006 Tropospheric O 3 from GOME for summer 1997 Liu et al., 2006 Dobson Units

AIRS Observations of an Asian Plume AIRS Total CO Column for 2006 May 5 May 6 May 7 May 8 Lin Zhang Daniel Jacob Wallace McMillan

April 2001 Dust Transport Event Observed from TOMS April 9/8 April 10/9 April 11/10 April 12/11 April 13/12 April 14/13

Aug 17 Aug 18 Aug 19 Aug 20 Aug 21 Aug 22 Aug 23 Aug 25 Aug 28 5 km 3 km 2006 Dust Transport Event Observed from CALIPSO David Winker

Attempting Quantitative Flux Estimates Yu et al., submitted Combines: -MODIS Aerosol Optical Depth (AOD) -Transport height from field experiments -AOD/mass from field experiments -GEOS-4 winds lution N 20-30N 30-40N 40-50N 50-60N Flux (Tg/year) GOCART BC+OM+Sulfate MODIS Pollution Latitude FLUX (Tg/yr)

Satellite Perspective Long-Range Transport Emissions

Close Relationship of NO x and VOC Emissions With Satellite Tropospheric NO 2 and HCHO Columns Emission NO NO 2 HNO 3 lifetime <day Nitrogen Oxides (NO x )Volatile Organic Compound (VOC) Emission VOC OH HCHO hours CO hours BOUNDARY LAYER Satellite NO / NO2   W ALTITUDE Tropospheric NO 2 column ~ E NOx Tropospheric HCHO column ~ E VOC O3O3 hv

Cloud-filtered Tropospheric NO 2 Columns Retrieved from SCIAMACHY 2004 –2005 Martin et al., 2006

GOME Satellite NO 2 Trends ( ) Richter et al., 2005

Day-to-day and Intra-day Variation in NO 2 Columns Beirle et al., 2003 Day of Week (GOME) SCIAMACHY (10 AM) – OMI (1:30 PM) for August 2006 Diurnal variation driven by diurnal variation in emissions and photochemistry Boersma et al., submitted

Top-Down Constraints on NOx Emissions SCIAMACHY Tropospheric NO 2 (10 15 molec cm -2 ) NO x emissions (10 11 atoms N cm -2 s -1 ) Martin et al., Inverse Modeling Reduction in NOx Emissions During Traffic Restrictions Observed by OMI Sino-African Summit in Beijing Wang et al., 2007 Date NOx Emissions

Algorithm for partitioning top-down NO x inventory Algorithm tested using synthetic retrieval GOME NO x emissions (2000) Fuel Combustion 1. Spatial location of FF- dominated regions in a priori (>90%) 1 Biomass Burning 2. Spatiotemporal distribution of fires used to separate BB/soil VIRS/ATSR fire counts Soils No fires + background 2 Jaeglé et al., 2005

Top-Down Constraints on Isoprene Emissions Inverse Modeling Millet et al., 2006 OMI HCHO Columns for June-Aug 2006 Isoprene Emissions Isoprene dominant source when Ω HCHO is high Ω HCHO variability over N. America driven by isoprene Other VOCs give rise to a relatively stable background Ω HCHO  Not to variability detectable from space Millet et al., submitted

Source Strengths Inferred from MOPITT CO Observations Pétron et al., 2004 Kopacz et al., submitted Correction factors to a priori Asian CO sources for February – April 2001 Adjustments in CO inventories

Aerosol Source Strengths from MODIS AOD Dubovik et al., 2007 Fine Aerosol Source (10 7 kg/day) MODIS AOD for August 19-30, 2000 AOD Inverse Model

Satellite Summary Important role in observing long-range transport and constraining emission estimates Near Term: (Considerable Data Mining Remains) –Evaluate and improve satellite retrievals –Additional in situ vertical profiles –Additional development of inverse modeling capability –Application of top-down information to inform bottom-up inventory development –Increasing data use with efficient interfaces Long Term –Few planned future launches –Geostationary platforms for temporal variation

In situ observations

Ozone and Precursors View major Westerly transport corridors –Trans Pacific, Atlantic, Europe-Asia Recognize complications –Background vs transport vs production vs stratospheric intrusion vs shifting transport patterns –Adequacy of measurement locations, frequencies and parameters

Back-trajectories, GEOS-Chem and chemical signature (Hg/CO) confirmed the Asian industrial source. (Jaffe et al., 2005; Weiss-Penzias et al 2006) Strong correlations between precursors In situ evidence for O3 and precursors: Asia to NA Observations at the Mt. Bachelor Observatory in central Oregon: April 25th, 2004

In situ evidence for O3 and precursor transport: Asia to NA Observations through airplanes (IGAC-ITCT-2K2 study) Adapted from Cooper et al., 2004; Nowak et al., 2004 Elevated CO on May 5, 10, 17 mark Asian emission plumes. Each CO plume accompanied by elevated oxidized nitrogen species at similar CO/NOy ratio Different stories for O3: - May 5 high altitude plume with little O3 enhancement; NOy in form of PAN. - May 10 high altitude plume with NOy in form of PAN; O3 likely from stratospheric intrusion. - May 17 plume descended from high altitude; PAN has been converted to NOx and then to HNO3; the NOx likely lead to in situ formation of O3, although stratospheric O3 contribution cannot be excluded

In situ evidence for O3 and precursor transport: NA to Europe Observations through airplanes (ICARTT) and modeling Real et al., 2004; 18 July measurements near North American East Coast A forest fire plume was sequentially sampled by three aircraft during transport across the North Atlantic Ocean Increasing O3 versus CO slope during trans-Atlantic transport indicates in situ O3 formation. Lagrangian model calculations (Pink and Blue symbols), initiated with black data points, give excellent reproduction of the measurements (indicated by Pink and Blue lines), 20 July measurements north of the Azores 23 July measurements near French Coast (Pink and Blue lines are linear regressions to 20 and 23 July measurement data.)

In situ evidence for O3 and precursor transport: Europe to Asia Mondy surface station, East Siberia: air masses delineated by origin Pochanart et al., 2004; Over land transport difficult to directly discern; occurs predominately within the continental boundary layer over Eurasia

Trends in Background Ozone

Ozone Summary Clear observational evidence of direct transport of O3 and precursors, as well as production across transport corridors Remaining questions –What is driving decadal increase in background O3 (and what can we say about very recent patterns?) –Can we delineate transport flux from “background” air? –Role of tracers (e.g., CO, Hg) in delineating source origins: anthropogenic, biomass nurning, start. intrusion –How well suited is our in situ observation system? –Role of satellites in tracking ozone?

Primary sources: dust, burning, sea spray, anthropogenic; and, Secondary formation processes (natural and anthropogenic) ? Defining “natural” and “anthropogenic” –Dust as carriers of anthropogenic sources –Behavioral impacts on natural events Aerosols

Aerosol outflow from continents In Situ and Lidar

North American Outflow: Impact on Bermuda IGAC AEROCE Westerly flows dominant in Winter, Spring associated with relative peak levels (Prospero, Jennings, Savoi) The Atmosphere/Ocean Chemistry Experiment: AEROCE Contributed by J. M. Prospero, University of Miami (Florida), USA and S.G. Jennings, University College Galway, Ireland Reprinted from IGACtivities Newsletter No. 7, December 1996.

Outflow form China observed at Cape Hedo, Okinawa Original dominant anthropogenic signal remains throughout dust event (Takami et al., 2006)

Aerosol Continental Inflow examples Barrie et al., 2001 Jaffe et al., 2005 Adopted from Brock et al., 2004: ITCT-2K2 dust Anthropogenic gases Biomass burning Delineating plume types through combined size distribution and CO profiles-May, 2002 event Observations at the Mt. Bachelor Observatory in central Oregon: April 25th, 2004

Aerosol summary Sufficient qualitative observational evidence of aerosol transport, and insights into secondary processes along transport corridors Major questions include: –Quantifying flux –Organic properties –Black C: source regions and removal processes –Developing an optimal observational approach –How do we integrate satellites, in situ measurements and global models

Impacts on surface air quality How does transport impact threshold and background levels of interest? Note: recent changes in U.S. NAAQS have reduced the daily PM2.5 standard from 65 to 35 μg/m3 and there is an expectation that the ozone standard (80ppbv 8hr-average) will be reduced. Such changes will elevate the relative contribution (to local) of transport. The 60 ppbv (1 hr) European ozone standard clearly is subjected to strong transport/background influences on a frequent basis. Jaffe et al., 2004 and 2003 June 6, 2003 Washington State, U.S. April, 2001

African Dust impacts on Barbados and U.S. (Prospero and Lamb, 2003) Note: Limited examples of “anthropogenic” aerosol transport (e.g., Jaffe et al., 2005) Shown earlier….implications for new US daily PM2.5 standard 35µg/m 3 Conclusion: Attribution to surface impacts requires advances in modeling systems and coupling of observations

Long term monitoring What can we say about decadal and greater time series Recognize the gaps in adequately sited stations and chemical species Often requires screening of coherent air masses not confounded by local sources Figure 3.6.1: Linear trends in median, normalized ozone concentrations at Kårvatn, mid-Norway, based on data filtered by back trajectory for only the background transport sectors. The boxes mark the annual medians, and the error bars the 25- and 75-percentiles. [EMEP/CCC 2005]

Trends of N.H. surface ozone data How confident are we in (the interpretation) these trends? (modified from Oltmans et al., 2006)

Aerosol Precursor Trends Figure 3.6.2: Anthropogenic sulfate concentrations on Midway compared to the emissions of SO2 from China [Prospero et al., 2003]. Note, uncertainty in NO3 trends in Barbados, Savoi et al., 2002

Summary comments on Trends Available trends data for O3, aerosols and precursors; but –Disagreement? over interpretation of ozone trends –Very limited number of sites –Only two decade record for ozone –Interannual variability compromising interpretation of aerosol trends –Reasonable interpretations of precursor (NOx, SOx) trends for aerosols –Scarcity of sites, data compromises ability to evaluate models University of Miami aerosol network discontinued

Conclusions Observations demonstrate profound impact of NH transport on distribution of ozone, aerosols and precursors Models are needed to conduct adequate attribution and projection assessments Confidence in attribution and projection will require marrying of observations and modeling Improvements in observational systems include:

Recommendations Long term surface stations Vertical profiling systems Satellites Intensive filed campaigns

Sustain and establish long term surface stations in critical transport paths - multi purpose: transport, climate change, trends, evaluation - adequate mix of precursor, indicator and “final” species - build on existing WMO/GAW structure

Vertical Profiling (sondes, lidar, aircraft) -Support expansion of MOZAIC/CARIBA -20 more flights + NOx, CO2, aerosols -Proposed sonde network ~ $20M/yr (Cooper) - ground based lidar systems (aerosols and ozone) Proposed sonde network