A Modeling Study of the Impact of the 2007 Greek Forest Fires on The

Atmospheric Research 149 (2014) 1–17 Contents lists available at ScienceDirect Atmospheric Research journal homepage: www.elsevier.com/locate/atmos A modeling study of the impact of the 2007 Greek forest ﬁres on the gaseous pollutant levels in the Eastern Mediterranean A. Poupkou a,⁎, K. Markakis a, N. Liora a, T.M. Giannaros a,2, P. Zanis b,U.Imc,1, N. Daskalakis c,d, S. Myriokefalitakis c, J.W. Kaiser e,f,g, D. Melas a, M. Kanakidou c, T. Karacostas b, C. Zerefos h,i a Laboratory of Atmospheric Physics, Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece b Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece c Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, Irakleio, Greece d Foundation for Research and Technology — Hellas, Institute of Chemical Engineering Sciences, Patras, Greece e King's College London, London, United Kingdom f European Centre for Medium-Range Weather Forecasts, Reading, United Kingdom g Max Planck Institute for Chemistry, Mainz, Germany h Research Centre for Atmospheric Physics and Climatology, Academy of Athens, Athens, Greece i Navarino Environmental Observatory (N.E.O.), Messinia, Greece article info abstract Article history: The main objective of the present study is the assessment of the non-radiative impact on the Received 21 January 2014 lower troposphere air quality of the intense biomass burning events that took place in the Eastern Received in revised form 15 May 2014 Mediterranean, when wild forest fires were burning in Peloponnesus (Greece) at the end of Accepted 15 May 2014 August 2007. The MM5-CAMx modeling system was applied in the Eastern Mediterranean in high Available online 25 May 2014 spatial and temporal resolution for the period 23 to 31 August 2007, forced by biomass burning emission fluxes from the Global Fire Emissions Database (version 3.0), in day-to-day temporal Keywords: and 0.1° spatial variability from the Global Fire Assimilation System. Enhancements of the CO Forest fires and NOx concentrations over almost the entire modeling domain were estimated due to the Eastern Mediterranean biomass burning, which were more pronounced over the burnt areas and maximum over the Air quality Peloponnesus forest fires. The domain-wide near surface mean concentration was higher by +6% Process analysis for CO and +11% for NOx because of the biomass burning. The near surface O3 values were reduced over the fire hot spots but increased over the greater part of the modeling domain. On the 26th August 2007, the maximum O3 concentrations reduction of about 12 ppb (i.e. −34%) was calculated over the Peloponnesus fires while the highest O3 increase of about 27 ppb (i.e. +52%) was estimated over the sea at 500 km downwind the Peloponnesus large forest fires. The process analysis revealed that on that day, the inclusion of the biomass burning emissions resulted in an enhancement of the daytime gas phase O3 production in the boundary layer in the Eastern Mediterranean and during some daytime hours in a change of the chemical regime from O3 destruction to O3 production. From 6 to 16 UTC, the O3 photochemistry in the boundary layer was VOC-sensitive close to the Peloponnesus fires, gradually changing to NOx-sensitive in the downwind fire plume. In the same period, the maximum impact on the oxidizing capacity of the boundary layer was an increase by 0.25 ppt for OH and a reduction by 13 ppt for HO2 mean concentrations over the Peloponnesus forest fires and an increase by 12 ppt for HO2 in the downwind plume. © 2014 Elsevier B.V. All rights reserved. ⁎ Corresponding author. Tel.: +30 2310998009. E-mail address: [email protected] (A. Poupkou). 1 Now at: Joint Research Centre (JRC), Air and Climate Unit, Ispra (VA), Italy. 2 Now at: National Observatory of Athens, Institute of EnvironmentalResearch and Sustainable Development, Vas. Pavlou & I. Metaxa, 15236,Penteli, Athens, Greece. http://dx.doi.org/10.1016/j.atmosres.2014.05.015 0169-8095/© 2014 Elsevier B.V. All rights reserved. 2 A. Poupkou et al. / Atmospheric Research 149 (2014) 1–17 1. Introduction pollutants emitted, the temporal evolution of fires and the vegetation and fire characteristics. Emission factors for over 100 Open biomass burning has been recognized as an impor- chemical components have been experimentally calculated for a tant source of pollutants emitted in the atmosphere, mainly range of biomes (Akagi et al., 2011; Andreae and Merlet, 2001). carbon monoxide (CO), nitrogen oxides (NOx), volatile organic However, several important features of fires that influence the compounds (VOCs) and particulate matter (PM). Biomass amount of material emitted by the fire may not be captured in burning is critical for the air quality on local, regional and many emission factors used in these estimates, including the fire hemispheric scales and is an important component of the phases (i.e. the flaming and smoldering phases). In addition, climate system (Carvalho et al., 2011; Sofiev et al., 2009; variation in timing of fires (or seasonality) is responsible for Schultz et al., 2008). Their impact on air quality depends also variation of emission factors within a biome (Keywood et al., on whether the plume is confined in the boundary layer or 2013). According to Langmann et al. (2009) and Monks et al. emitted also above it and transported downwind over very (2009), the accumulation of uncertainties at virtually every long distances, e.g. emission and transport of ozone (O3) step in the emission estimation process results in a factor of precursors, such as CO, NOx, and VOCs, the chemistry of which two variations in global estimates of carbon emissions from can produce large surface O3 concentrations far away from the fires.Theexistenceoflargedifferencesthatcanbeofanorderof initial emission location (Amiridis et al., 2010; Coheur et al., magnitude, in the European scale forest fires CO emissions has 2009; Freitas et al., 2007; Langmann et al., 2009; Morris et al., been identified in NATAIR (2007). Large forest fires can generate 2006). smoke plumes with large vertical extent due to the release The Eastern Mediterranean during summertime is char- of heat in the combustion process. Determining the correct acterized by specific meteorological and climate conditions injection height of emissions is essential since transport and (i.e. sunny, hot and dry climate) that favor the enhanced deposition processes are very sensitive to altitude (Pizzigalli photochemistry and the possible increased danger for fire et al., 2012). Methods have been proposed in literature to events. North sector winds, i.e. the Etesian winds, are blowing estimate the injection height of fire emissions either using some in the Aegean Sea with great constancy during the summer and empirical relationship between the injection height and fire early autumn. The Etesians blow in sequences of several days intensity (Lavoue et al., 2000) or estimations of the fire buoyant and can reach gale force (Poupkou et al., 2011) allowing long efficiency (Hodzic et al., 2007) or a more refined sub-grid scale range transport of pollution and possibly enhancing the fire plume rise mechanism (Freitas et al., 2007). However, in air propagation in case of a biomass burning event in Greece. In quality modeling studies, fire emissions are commonly distrib- summer, in the Eastern Mediterranean, the biomass burn- uted within the boundary layer or in a few layers close to the ing emissions are mixed with a diversity of anthropogenic surface (Martins et al., 2012; Wang et al., 2006). emissions of pollutants emitted in urban scale, i.e. in the There have been previously studies revealing the impor- megacity of Istanbul and other large urban agglomerations tant impact of open biomass burning on the air quality like Athens, as well as in regional scale, like for example the in regional scale. Konovalov et al. (2011) used a modified pollutant emissions from the maritime transport in the version of the chemistry transport model CHIMERE in order study domain which connects Europe, Asia and Africa and is to study the influence of the numerous biomass burning characterized by long coastline and numerous islands. They are events during the 2010 summer over the European Russia on also mixed with natural emissions (e.g. high VOCs emissions the air pollution levels in the Moscow region. The model from vegetation in summertime) (Symeonidis et al., 2008). results showed that the wildfires were the principal factor Including fire effects on the air quality assessment and causing air pollution episodes associated with extremely high modeling has become more frequent during the past decade levels of daily mean CO and PM10 concentrations (up to (Martins et al., 2012; Konovalov et al., 2011; Pfister et al., 10 mg m−3 and 700 μgm−3 in the averages over available 2008; Junquera et al., 2005). Evaluating and accounting for monitoring sites, respectively). Lazaridis et al. (2008) applied biomass burning emissions in the analyses of regional air the air quality modeling system UAM-AERO to quantify the quality and climate model results are important especially for contribution of widespread forest fires in the Greek mainland the southeastern Europe, since future scenarios on climate to the air pollution levels in Greece during the period 12 to 16 change indicate that the already hot and dry climate of this July 2000. It was estimated that the forest fire emissions were area is expected to

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