Observation and Modeling Evidence of Ozone Transport to and from AsiaHajime Akimoto(Oliver Wild and Pakpong Pochanart)Frontier Research Center for Global Change (FRCGC)Japan Agency for Marine-Earth Science and Technology (JAMSTEC)LRTAP/EMEP Task Force on Hemispheric Transport of Air Pollutants, Brussels, June 1-3, 2005

Intercontinental Transport at Northern Mid-latitudesFree TroposphereBoundary LayerN. AmericaAsiaEuropeHHHLLL

Trans-Eurasian TransportMotivationsTrans-Pacific and Trans-Atlantic transport well studiedPEM-West, TRACE-P, ACE-Asia, NARE, ITCTTrans-Eurasian transport less well understood Unique featuresmeteorological mechanisms for exportchemical influences due to latitude and meteorologyemissions and deposition over continentQuestionsHow does pollutant export differ from that from N. America or East Asia? What are the impacts on oxidation and climate?To what extent does European pollution affect central and eastern Asia? How does this compare with N. American influence?

10% Increase of Emission in N. America10% Increase of Emission in Europe10% Increase of Emission in E. Asia Model-calculated Characteristic of Intercontinental Transport from Three ContinentsAdapted from: O. Wild, H. Akimoto, J. Geophys. Res., 106, 27,729 (2001)longitudeHeightlongitudelongitude

O3 and CO over EurasiaMace HeadZugspitzeMondyHappo

Export of Oxidants from EuropeHorizontal transport in PBL dominates exportSeasonal variation in export dependent on species

Can European Pollution Affect East Asia?Source: Newell and Evans [2000]

Trajectories Arriving at 100E Newell and Evans [2000]

European Impacts at 100ECO: greatest in high-latitude PBL in wintertimeO3: greatest in low/mid-trop in spring close to zero in winter PBL

Remote Stations for Surface O3 from Europe to East Asia Mountain (1600-2000 m): Arosa, Mondy and HappoSea Level: Mace Head, Oki, and Okinawa

Arosa, SwitzerlandMondy, RussiaHappo, Japan

Seasonal Variation of Background Ozone in East Asia and Europe -Observation-

Seasonal Variation of Regionally Polluted Ozone in East Asia and Europe -Observation-

Differences in Surface Ozone between Europe and East Asia Derive regional backgroundremove local emissions

Compare:Mace Head (Ireland)Arosa (Switzerland)Mondy (Siberia)Happo (Japan)

East Asian Ozone lower in summer due to Asian monsoon

Ozone 5-10 ppbv higher at Asian sites from autumn to spring Why ?

Differences in Surface Ozone between Europe and East AsiaConsider mean differenceAsian sites European siteslocal emissions removed

Stratospheric influence greater over Asia driven by subsidence over Central Asia

Residual largely due to:emissions over Europeemissions over Eurasia

Background O3 higher over Asiaimplications for air quality

Impacts of European Sources at 100 EastCOWinter/spring maximum, summer minimumBoundary layer impacts greatestO3Spring maximum, summer minimumAdditional minimum in winterGreater impacts in mid-troposphereMondy, 52NCan we detect European influence from the measurements?

Raw obserbational data of O3 and CO at Mondy during 1996-99Pochanart, Akimoto et. al Atmos. Environ., 2001O3CO

Classification based on trajectoriesEUEUSISIHLHLO3O3COCOMonthly Mean DataFrequency Distributions (Annual Data)

Comparison of Ozone in European Air mass with Others by SeasonSpringSummerWinter

Impact of O3 and CO over Happo, Japan from Europe and N. America

Impacts on O3 and CO over Happo, Japan from Europe and N. America in April 1996O3CO

Contribution to Surface O3 at Happo by Difference Sources in April 199660 ppbv 1hr av.European/N.American impacts persist during local pollution episodes (Apr 23-27): affect attainment of air quality standardsJapan EQS for Ox

Seasonal Variation of Trajectory Categorized ozone in JapanRishiriOkiOkinawaOgasawara

Trend of Annual Average Concentration of Ox and Precursors in Tokyo (Average of 23 Stations)Oxidant Measure Committee Report, Tokyo Metropolitan Government (2005)

Long-term measurements needed over EurasiaRegional coverage over Asia relatively poorTransport from Europe occurs at high latitudesMore sites needed over Central and Northern AsiaMondyWaliguanVostochnaya (?)EMEP SitesEANET/ GAW Sites & China

ConclusionsFrom CTM StudieSignificant European impacts over Central AsiaAverage 10-30 ppbv CO, 1-4 ppbv O3Only slightly smaller impacts over JapanAverage 2-25 ppbv CO, 0.2-2.5 ppbv O3Present during anticyclonic conditions (affect AQ Stds)N. American influence larger than European in mid-trop

From ObservationsSignature of European influence present in O3 and COStill difficult to quantify directly (new methods needed?)