ICARTT 2004 Data Workshop. Durham, New Hampshire, August 9-12, 2005.We present measurements of CO, O3, aerosol Black Carbon (BC) made over the central North Atlantic lower Free Troposphere (FT) during the summers of 2001-2004 along with measurements of nitrogen oxides (NOx and NOy) made during the summer of 2004 (ICARTT period) and non-methane hydrocarbons (NMHCs) made during the winter 2004-spring 2005

Fialho, Paulo

Helmig, Detlev

Honrath, Richard

Kleissl, J.

Lapina, K.

Owen, Robert

Tanner, D. M.

Val Martin, Maria

Repositório da Universidade dos Açores

Impacts of Anthropogenic and Boreal Forest Fire Emissions in the Central North Atlantic Lower Free Troposphere:Summertime Observations at the PICO-NARE ObservatoryM. Val Martin1, R. E. Honrath1, J. Kleissl1, R. C. Owen1, K. Lapina1, P. Fialho2, D. Helmig3, and D. Tanner31Department of Civil and Environmental Engineering, Michigan Technological University, U.S.2Grupo de Qumica e Fisica da Atmosfera, Universidade dos Acores, Portugal3Institute of Arctic and Alpine Research, University of Colorado, U.S.2. STATION OVERVIEWThe PICO-NARE station is located in the Azores Islands, Por-tugal (2225 m asl), which is an ideal location for sampling NorthAmerican pollution, forest fire emissions, and clean marinebackground air [Fig. 1].Free Tropospheric Air Sampling?The station altitude is well into the FT in all seasons [Figs. 2-3].However, marine boundary layer (MBL) air occasionally reachesthe station due to daytime buoyant uplift (periods of weak winds)and mechanically driven uplift [1] (periods of strong winds)[Figs. 3-4]. -160-140-120-100-80 -60 -40-2002001020304050607080900 2 4 6 8 10 12500100015002000monthheight [m]4. IMPACTS OF U.S. ANTHROPOGENIC EMISSIONSEnhancements of CO, O3, BC, NOx, NOy and NMHCs levels above background also occur during flow from the U.S. [Fig. 8]. Mostof these events travel in the lower FT in a route governed by the Azores-Bermuda High and transient northerly lows [11], and typi-cally have a photochemical age of 5-10 days as indicated by the “NMHC clock” [Fig. 9] and backward trajectories (not shown).Evidence of Increased O3 Export from the U.S.?In 2001, few fires were observed and nearly all periods of elevated CO and O3 occurred during U.S.outflow. The d[O3]/d[CO] slope during these periods was unexpectedly higher than those reported previ-ously over the North Atlantic region, even after accounting for CO loss and for declining North AmericanCO emissions [Fig. 10] [12]. This suggests an addition of significant amount of O3 to air reaching Pico in2001, relative to air near North America in the early 1990s.3c. Increase in Summertime O3 Background?To minimize the effect of transportdifferences in the assessment ofboreal fire impacts on O3, we com-pare observations in 2 subsets ofeach summer data: air that travellednorth of 50oN, but low CO, and airthat travelled north of 50oN with rela-tively high CO (indicating likely fireemissions) [Fig.7]. The high-CO sub-set exhibit ~20 ppbv higher medianO3, implying significant O3 productionfrom fire-emitted precursors [10].3b. Interannual VariabilitySummertime CO, BC and O3 levelswere higher in 2002 than in 2001, andmuch higher in 2003-2004 [Fig. 6].This increase is attributed toenhanced fires in Quebec in 2002,and much enhanced fires in Siberia in2003 and in Alaska and western Can-ada in 2004 [9].5. CONCLUSIONS AND FINAL REMARKS• Large boreal wildfires in 2002-2004 strongly impacted theair quality over the central North Atlantic lower FT, and dom-inated the interannual variability of CO, O3 and aerosol BC over2001-2004. The frequency distribution of O3 shifted towardhigher levels, suggesting impacts on the summertime O3background over the region.• Nitrogen oxides levels during fire-impacted periods wereextremely high for such a remote region (e.g., NOx > 150pptv), suggesting that significant additional O3 productionmust have occurred in these well-aged boreal fires plumes.* This deserves further study since little is known about theimpact of boreal wildfires on the O3 levels in the NorthernHemisphere. Boreal wildfire activity is expected to increasein the future due to an increase in temperatures resultingfrom global climate change [15].• O3 enhancements during U.S. outflow transported to thesite over 5-10 days were significantly higher than thosereported from previous observations.*Further work is needed to determine whether this indicateslarger O3 impacts from U.S. emissions that simulated byGlobal Chemical Transport Models.•The PICO-NARE station has been proved to be a valuableplatform for observations of the regional background and U.S.and boreal fires impacts. (It is also impacted by European andAfrican emissions, although less frequently).*Additional climate-relevant measurements (CO2, aerosols,and CCN) are planned beginning in 2006 (support pending).PICO-NARE CO2 and O3 observations will be incorporatedinto the NOAA-CMDL record.*We are working to convert the station into a permanent,Portuguese GAW observatory over the next ~3 years.1. INTRODUCTIONWe present measurements of CO, O3, aerosol Black Carbon(BC) made over the central North Atlantic lower Free Tropo-sphere (FT) during the summers of 2001-2004 along with mea-surements of nitrogen oxides (NOx and NOy) made during thesummer of 2004 (ICARTT period) and non-methane hydrocar-bons (NMHCs) made during the winter 2004-spring 2005.Main Findings: Anthropogenic and boreal wildfire emis-sions dominate impacts on CO, O3, NOx, NOy, BC, andNMHCs over the North Atlantic lower FT during summerseasons.FIGURE 1. Location of the PICO-NARE station in the Azores Islands. Also shown aretypical flow pathways that carry boreal fire emissions (blue), U.S. anthropogenic emis-sions (red) and clean marine background air (purple) to the station. Dots indicate each2 days upwind. Also shown are a simulated view of the central Azores Islands and aview of the northwest side of Pico Island from an altitude of 6 km (Nasa Worldwind).FIGURE 2. View of the Pico mountain andview of the station near the cliff at the sum-mit. MBL-capping clouds are visible beyond.Also visible is the ITOP BAE 146 airplaneduring an intercomparison flyby.FIGURE 3. Annual cycle of MBL height(dashed) based on FNL data. Alsoshown is the dividing streamlineheight (solid), which is the minimumheight of air transported to the summitby mechanical orographic uplifting.Lines connect medians, and error barsspan from 1st to 3rd quartiles.Ozone Distributions in NNA Flow: Low-CO and High-CO Subsets0 20 40 60 80 100Ozone (ppbv)0.00.10.20.30.4Fraction of ObservationsOzone distribution, low-CO200120032004 Ozone distribution, high-CO200120032004Mon Apr 25 04:45:31 2005Jun 1000:00Jun 1004:15Jun 1008:30Jun 1012:45Jun 1017:00050100150200250300NOy, NOx (pptv)020406080100120140CO, O3 (ppbv); BC (ng/m3)NOyNOxCOO3BCSpring 2005 event: CO, O3 and alkanes04/15/0500:0004/18/0500:0004/21/0500:0004/24/0500:0004/27/0500:0004/30/0500:00-50050100150CO, O3 (ppbv)020040060080010001200ethane/5, n-butane, propane (pptv)COO3ethane/5propanen-butaneWed Jun 29 14:02:39 2005FIGURE 9. Apparent photochemical age determined from HC/HCratios. Blue symbols show all winter 2004--spring 2005 HC observa-tions; the red circles show data during the period of maximum mix-ing ratios around 4/18 and the green circles show data during theperiod of minimum mixing ratios around 4/20 [Fig. 8]. The lower andupper lines show the expected trend on this plot resulting from purephotochemical aging (reaction with OH) or mixing with backgroundair. Approximate ages since emission are written along the centerline, which reflects a combination of mixing and photochemicalaging.FIGURE 8. Observations of CO, O3, NOx, NOy, BC, and NMHCsduring two possible U.S. airflow events in summer 2004 andspring 2005. Arrows identify periods plotted in Fig. 9.Summer 2004 event:CO, O3, NOx, NOy, and BCFIGURE 10. Comparison of the 2001 Picod[O3]/d[CO] to a-priori expectations [12-14].REFERENCES[1] Kleissl J. et al.,Analysis and application of Sheppard’s airflow model to predict mechanical orographic lifting, JAM, in prepara-tion.[2] Andreae, M. O. et al., Emission of trace gases and aerosols from biomass burning, GBC, 15, 2001.[3] Val Martin, M. et al. Observations of enhanced nitrogen oxides levels from boreal wildfires in the North Atlantic lower free tro-posphere. GRL, in preparation.[4] Bertschi I.T and Jaffe D.A. Long-range transport of O3, CO, aerosol to the NE Pacific troposphere. during the summer of2003: Observations of smoke plumes from Asian boreal fires. JGR, 110, 2005.[5] Mauzerall, D. L. et al., Origin of tropospheric ozone at remote high northern latitudes in summer. JGR, 101,1996.[6] McKeen, S.A. et al., Ozone production from Canadian wildfires during June and July of 1995. JGR, 10.1029/2001JD000697,2002.[7] Wofsi S. C., et al., Atmosp. chemistry in the arctic and subarctic: Influence of natural fires, industrial emissions, and strato-spheric inputs. JGR, 97, 1992.[8] DeBell, L. J., et al. A major regional air pollution event in the northeastern United States caused by extensive forest fires inQuebec, Canada. JGR, 109, 2004.[9] Kasischke, E. S. et al., Influences of boreal fire emissions on Northern Hemisphere atmospheric carbon and carbon monox-ide. GBC, 19, 2005.[10] Lapina, K. et al., Impact of large-scale boreal fires on levels of tropospheric ozone in the Northern Hemisphere. GRL, inpreparation.[11] Owen, R.C. et al., Mechanism of North American export and transport to the central North Atlantic lower FT during July2003. JGR, in preparation.[12] Honrath, R.E et al., Regional and hemispheric impacts of anthropogenic and biomass burning emissions on summertimeCO and O3 in the North Atlantic lower FT. JGR, 119, 10.1029/2004JD005147, 2004.[13] Parrish, D.D. et al., Relationship between O3 and CO at surface sites in the North Atlantic region. JGR, 103, 1998.[14] Parrish, D.D. et al., Decadal change in carbon monoxide to nitrogen oxide ratio in U.S. vehicular emissions. JGR, 2002.[15] Stocks, B.J., et al., Large forest fires in Canada, 1959-1997. JGR, 108, 2003.PICO-NARE Site2225 ma) b)3. LARGE IMPACTS OF BOREAL WILDFIRES3a. Strong Variability in CO, O3, NOx, NOy and Aerosol BCMajor fires in Alaska and western Canada repeatedly impacted our station during the summer 2004. Extreme enhancements of CO, O3, NOx, NOy,BC, and NMHCs (not shown) levels above background occurred during these periods [Fig. 4].• d[O3]/d[CO] was similar to some previous reports for well-aged forest fire plumes, although in some cases O3 production was sup-pressed, especially in the most concentrated part of the plume [Fig. 5a].• d[NOy]/d[CO] was a significant fraction of the estimated NOx/CO ratio [2] and only moderately smaller than previous measurements muchcloser to fires [Fig.5b], indicating limited NOy removal during transport to the site and an additional potential for O3 formation downwind [3].ACKNOWLEDGEMENTSWe thank Dr. Andreas Stohl for sharing simulations of the FLEXPART model. Technical andlogistical support was provided by Mike Dziobak (MTU). Additional field assistance was providedby Forca Aerea Portuguesa, and Bombeiros Voluntarios do Madalena do Pico. Jessica Strane(MTU) assisted with the analysis of the airflow events. This work was supported by NOAA/OGPgrant NA030AR4510002 and NA16GP1658, and NSF grant ATM-0215843.FIGURE 7. Frequency distributions of O3observations in northern North America flowonly, divided into high-CO and low-CO sub-sets.Maria Val Martin: mvalmart@mtu.eduDr. Richard Honrath: reh@mtu.eduJul 2212:00Jul 2218:00Jul 2300:00Jul 2306:00Jul 2312:0050150250CO (ppbv)205080Ozone (ppbv)06501300NOy (pptv)0350700Black Carbon (ng m-3)Aug 3100:00Sep 0100:00Sep 0200:00Sep 0300:0050150250CO (ppbv)205080Ozone (ppbv)06501300NOy, NOx (pptv)0350700Black Carbon (ng m-3)Jul 0100:00Jul 0600:00Jul 1200:00Jul 1700:00Jul 2300:00Aug 0100:00020040060080010001200NOy, NOx (pptv)-50050100150200250CO, O3 (ppbv); BC/4 (ng/m3)NOyNOxCOO3BCFLX-BBAug 0100:00Aug 0700:00Aug 1300:00Aug 2000:00Aug 2600:00Sep 0400:00020040060080010001200NOy, NOx (pptv)-50050100150200250CO, O3 (ppbv); BC/4 (ng/m3)NOyNOxCOO3BCFLX-BBFIGURE 4. CO, O3, NOx, NOy, BC, and Flexpart boreal fire CO tracer during summer 2004. Periodsmarked by bars along the top of the plot are events attributed to boreal fire emissions (based onanalyses of back trajectories, MODIS images, and correlations among the species). Hatched areasshow periods when buoyant and mechanically driven upslope flow may have impacted the site;these periods are not considered in the analyses. Also shown are two events in more detail. Blue andred bars on top of the plots indicate some of the periods plotted in Fig. 5.Ozone vs CO50 100 150 200 250CO (ppbv)20304050607080O3 (ppbv)ABLE-3A/BMcKeen02ABLE-3B(max)Bertschi05maxNOy vs CO50 100 150 200 250CO (ppbv)020040060080010001200NOy (pptv)Andreae01DeBell04ABLE-3A(avg)ABLE-3B(avg)FIGURE 5. Scatter plots of O3 and NOy against CO during thesummer 2004 boreal fire events. Periods with apparently differingd[O3]/d[CO] are in red. Also shown are O3-CO and NOy-COenhancement ratios from previous observations [2,4-8].FIGURE 6. Cumulative distributions of allhourly average observations of BC, CO and O3during the 2001-2004 summers.Absorption expressed as Black Carbon0 100 200 3000.00.20.40.60.81.0Black Carbon (ng m-3)2001200220032004CO0 50 100 150 2000.00.20.40.60.81.0CO (ppbv)2001200220032004Ozone0 20 40 60 800.00.20.40.60.81.0O3 (ppbv)2001200220032004Thu Jun 23 19:24:46 2005NOTE: O3 data unavailableduring summer 2002) b)

Impacts of anthropogenic and boreal fire emissions in the central North Atlantic lower free troposphere: summertime observations at the PICO-NARE observatory.

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Impacts of anthropogenic and boreal fire emissions in the central North Atlantic lower free troposphere: summertime observations at the PICO-NARE observatory.

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