scholarly journals Transport of anthropogenic and biomass burning aerosols from Europe to the Arctic during spring 2008

2015 ◽  
Vol 15 (7) ◽  
pp. 3831-3850 ◽  
Author(s):  
L. Marelle ◽  
J.-C. Raut ◽  
J. L. Thomas ◽  
K. S. Law ◽  
B. Quennehen ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Monitoring And Evaluation ◽  
Conveyor Belt ◽  
Airborne Lidar ◽  
Lagrangian Model ◽  
The Arctic ◽  
Aircraft Measurements ◽  
Source Regions ◽  
Vertical Distributions ◽  
Research Aircraft

Abstract. During the POLARCAT-France airborne campaign in April 2008, pollution originating from anthropogenic and biomass burning emissions was measured in the European Arctic. We compare these aircraft measurements with simulations using the WRF-Chem model to investigate model representation of aerosols transported from Europe to the Arctic. Modeled PM2.5 is evaluated using European Monitoring and Evaluation Programme (EMEP) measurements in source regions and POLARCAT aircraft measurements in the Scandinavian Arctic. Total PM2.5 agrees well with the measurements, although the model overestimates nitrate and underestimates organic carbon in source regions. Using WRF-Chem in combination with the Lagrangian model FLEXPART-WRF, we find that during the campaign the research aircraft sampled two different types of European plumes: mixed anthropogenic and fire plumes from eastern Europe and Russia transported below 2 km, and anthropogenic plumes from central Europe uplifted by warm conveyor belt circulations to 5–6 km. Both modeled plume types had undergone significant wet scavenging (> 50% PM10) during transport. Modeled aerosol vertical distributions and optical properties below the aircraft are evaluated in the Arctic using airborne lidar measurements. Model results show that the pollution event transported aerosols into the Arctic (> 66.6° N) for a 4-day period. During this 4-day period, biomass burning emissions have the strongest influence on concentrations between 2.5 and 3 km altitudes, while European anthropogenic emissions influence aerosols at both lower (~ 1.5 km) and higher altitudes (~ 4.5 km). As a proportion of PM2.5, modeled black carbon and SO4= concentrations are more enhanced near the surface in anthropogenic plumes. The European plumes sampled during the POLARCAT-France campaign were transported over the region of springtime snow cover in northern Scandinavia, where they had a significant local atmospheric warming effect. We find that, during this transport event, the average modeled top-of-atmosphere (TOA) shortwave direct and semi-direct radiative effect (DSRE) north of 60° N over snow and ice-covered surfaces reaches +0.58 W m−2, peaking at +3.3 W m−2 at noon over Scandinavia and Finland.

scholarly journals Transport of anthropogenic and biomass burning aerosols from Europe to the Arctic during spring 2008

2014 ◽  
Vol 14 (21) ◽  
pp. 28333-28384
Author(s):  
L. Marelle ◽  
J.-C. Raut ◽  
J. L. Thomas ◽  
K. S. Law ◽  
B. Quennehen ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Conveyor Belt ◽  
Airborne Lidar ◽  
Lagrangian Model ◽  
The Arctic ◽  
Aircraft Measurements ◽  
Source Regions ◽  
Vertical Distributions ◽  
Research Aircraft ◽  
European Arctic

Abstract. During the POLARCAT-France airborne campaign in April 2008, pollution originating from anthropogenic and biomass burning emissions was measured in the European Arctic. We compare these aircraft measurements with simulations using the WRF-Chem model to investigate model representation of aerosols transported from Europe to the Arctic. Modeled PM2.5 is evaluated using EMEP measurements in source regions and POLARCAT aircraft measurements in the Scandinavian Arctic, showing a good agreement, although the model overestimates nitrate and underestimates organic carbon in source regions. Using WRF-Chem in combination with the Lagrangian model FLEXPART-WRF, we find that during the campaign the research aircraft sampled two different types of European plumes: mixed anthropogenic and fire plumes from eastern Europe and Russia transported below 2 km, and anthropogenic plumes from central Europe uplifted by warm conveyor belt circulations to 5–6 km. Both modeled plume types had significant wet scavenging (> 50% PM10) during transport. Modeled aerosol vertical distributions and optical properties below the aircraft are evaluated in the Arctic using airborne LIDAR measurements. Evaluating the regional impacts in the Arctic of this event in terms of aerosol vertical structure, we find that during the 4 day presence of these aerosols in the lower European Arctic (< 75° N), biomass burning emissions have the strongest influence on concentrations between 2.5 and 3 km altitudes, while European anthropogenic emissions influence aerosols at both lower (~1.5 km) and higher altitudes (~4.5 km). As a proportion of PM2.5, modeled black carbon and SO4= concentrations are more enhanced near the surface. The European plumes sampled during POLARCAT-France were transported over the region of springtime snow cover in Northern Scandinavia, where they had a significant local atmospheric warming effect. We find that, during this transport event, the average modeled top of atmosphere (TOA) shortwave direct and semi-direct radiative effect (DSRE) north of 60° N over snow and ice-covered surfaces reaches +0.58 W m−2, peaking at +3.3 W m−2 at noon over Scandinavia and Finland.

GLORIA observations of pollution tracers C2H6, C2H2, HCOOH, and PAN in the North Atlantic UTLS region

2020 ◽  
Author(s):  
Gerald Wetzel ◽  
Felix Friedl-Vallon ◽  
Norbert Glatthor ◽  
Jens-Uwe Grooß ◽  
Thomas Gulde ◽  
...  
Keyword(s):  
High Altitude ◽  
North Atlantic ◽  
Atmospheric Chemistry ◽  
Emission Spectra ◽  
Infrared Region ◽  
Reanalysis Data ◽  
Lagrangian Model ◽  
Back Trajectories ◽  
Source Regions ◽  
Research Aircraft

&lt;p&gt;The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an imaging Fourier transform spectrometer (iFTS) using a 2-dimensional detector array to record emission spectra in the mid-infrared region with high spatial resolution. GLORIA is operated on high altitude research aircraft, mainly in the limb observational geometry to measure vertical profiles of temperature and atmospheric trace species with high vertical resolution.&lt;/p&gt;&lt;p&gt;In autumn 2017, the Wave-driven ISentropic Exchange (WISE) aircraft campaign took place from Shannon (Ireland). Sixteen flights with the High Altitude and Long Range Research Aircraft (HALO) were performed between 31 August and 21 October 2017 over the eastern North Atlantic region.&lt;/p&gt;&lt;p&gt;GLORIA observations were analysed with regard to pollutant species like C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;6&lt;/sub&gt;, C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;, HCOOH, and PAN, which are produced at distinct source regions near the ground and transported to remote regions due to their atmospheric lifetime of several weeks. Enhanced volume mixing ratios of these molecules were detected along some parts of the flight track in the upper troposphere and lowermost stratosphere (UTLS).&lt;/p&gt;&lt;p&gt;Measured profiles of these species are compared to simulations from the ECHAM/MESSy Atmospheric Chemistry (EMAC) model and reanalysis data from the Copernicus Atmosphere Monitoring Service (CAMS). Furthermore, emission tracers and back-trajectories from the Chemical Lagrangian Model of the Stratosphere (CLaMS) are used to analyse the source regions of these pollution events.&lt;/p&gt;

scholarly journals Source sector and region contributions to black carbon and PM<sub>2.5</sub> in the Arctic

2018 ◽  
Vol 18 (24) ◽  
pp. 18123-18148 ◽  
Author(s):  
Negin Sobhani ◽  
Sarika Kulkarni ◽  
Gregory R. Carmichael
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Surface Concentration ◽  
The Arctic ◽  
Anthropogenic Emissions ◽  
Economic Sectors ◽  
Modeling Framework ◽  
Source Regions ◽  
Geographical Regions ◽  
Chinese Industry

Abstract. The impacts of black carbon (BC) and particulate matter with aerodynamic diameters less than 2.5 µm (PM2.5) emissions from different source sectors (e.g., transportation, power, industry, residential, and biomass burning) and geographic source regions (e.g., Europe, North America, China, Russia, central Asia, south Asia, and the Middle East) to Arctic BC and PM2.5 concentrations are investigated through a series of annual sensitivity simulations using the Weather Research and Forecasting – sulfur transport and deposition model (WRF-STEM) modeling framework. The simulations are validated using observations at two Arctic sites (Alert and Barrow Atmospheric Baseline Observatory), the Interagency Monitoring of Protected Visual Environments (IMPROVE) surface sites over the US, and aircraft observations over the Arctic during spring and summer 2008. Emissions from power, industrial, and biomass burning sectors are found to be the main contributors to the Arctic PM2.5 surface concentration, with contributions of ∼ 30 %, ∼ 25 %, and ∼ 20 %, respectively. In contrast, the residential and transportation sectors are identified as the major contributors to Arctic BC, with contributions of ∼ 38 % and ∼ 30 %. Anthropogenic emissions are the most dominant contributors (∼ 88 %) to the BC surface concentration over the Arctic annually; however, the contribution from biomass burning is significant over the summer (up to ∼ 50 %). Among all geographical regions, Europe and China have the highest contributions to the BC surface concentrations, with contributions of ∼ 46 % and ∼ 25 %, respectively. Industrial and power emissions had the highest contributions to the Arctic sulfate (SO4) surface concentration, with annual contributions of ∼ 43 % and ∼ 41 %, respectively. Further sensitivity runs show that, among various economic sectors of all geographic regions, European and Chinese residential sectors contribute to ∼ 25 % and ∼ 14 % of the Arctic average surface BC concentration. Emissions from the Chinese industry sector and European power sector contribute ∼ 12 % and ∼ 18 % of the Arctic surface sulfate concentration. For Arctic PM2.5, the anthropogenic emissions contribute > ∼ 75 % at the surface annually, with contributions of ∼ 25 % from Europe and ∼ 20 % from China; however, the contributions of biomass burning emissions are significant in particular during spring and summer. The contributions of each geographical region to the Arctic PM2.5 and BC vary significantly with altitude. The simulations show that the BC from China is transported to the Arctic in the midtroposphere, while BC from European emission sources are transported near the surface under 5 km, especially during winter.

Gust factor based on research aircraft measurements: a new methodology applied to the Arctic marine boundary layer

2016 ◽  
Vol 142 (701) ◽  
pp. 2985-3000 ◽  
Author(s):  
Irene Suomi ◽  
Christof Lüpkes ◽  
Jörg Hartmann ◽  
Timo Vihma ◽  
Sven-Erik Gryning ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
The Arctic ◽  
Aircraft Measurements ◽  
Gust Factor ◽  
Research Aircraft

scholarly journals Atmospheric VOC measurements at a High Arctic site: characteristics and source apportionment

2021 ◽  
Vol 21 (4) ◽  
pp. 2895-2916
Author(s):  
Jakob B. Pernov ◽  
Rossana Bossi ◽  
Thibaut Lebourgeois ◽  
Jacob K. Nøjgaard ◽  
Rupert Holzinger ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Dimethyl Sulfide ◽  
High Arctic ◽  
Anthropogenic Sources ◽  
The Arctic ◽  
Research Station ◽  
Source Regions ◽  
Arctic Haze

Abstract. There are few long-term datasets of volatile organic compounds (VOCs) in the High Arctic. Furthermore, knowledge about their source regions remains lacking. To address this matter, we report a multiseason dataset of highly time-resolved VOC measurements in the High Arctic from April to October 2018. We have utilized a combination of measurement and modeling techniques to characterize the mixing ratios, temporal patterns, and sources of VOCs at the Villum Research Station at Station Nord in northeastern Greenland. Atmospheric VOCs were measured using proton-transfer-reaction time-of-flight mass spectrometry. Ten ions were selected for source apportionment with the positive matrix factorization (PMF) receptor model. A four-factor solution to the PMF model was deemed optimal. The factors identified were biomass burning, marine cryosphere, background, and Arctic haze. The biomass burning factor described the variation of acetonitrile and benzene and peaked during August and September. The marine cryosphere factor was comprised of carboxylic acids (formic, acetic, and C3H6O2) as well as dimethyl sulfide (DMS). This factor displayed peak contributions during periods of snow and sea ice melt. A potential source contribution function (PSCF) showed that the source regions for this factor were the coasts around southeastern and northeastern Greenland. The background factor was temporally ubiquitous, with a slight decrease in the summer. This factor was not driven by any individual chemical species. The Arctic haze factor was dominated by benzene with contributions from oxygenated VOCs. This factor exhibited a maximum in the spring and minima during the summer and autumn. This temporal pattern and species profile are indicative of anthropogenic sources in the midlatitudes. This study provides seasonal characteristics and sources of VOCs and can help elucidate the processes affecting the atmospheric chemistry and biogeochemical feedback mechanisms in the High Arctic.

scholarly journals Vertical profile of atmospheric dimethyl sulfide in the Arctic Spring and Summer

2017 ◽  
Author(s):  
Roghayeh Ghahremaninezhad ◽  
Ann-Lise Norman ◽  
Betty Croft ◽  
Randall V. Martin ◽  
Jeffrey R. Pierce ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Transport Model ◽  
Open Water ◽  
The Arctic ◽  
Chemical Transport Model ◽  
Air Mass ◽  
Baffin Bay ◽  
Mixing Ratios ◽  
Vertical Distributions ◽  
Research Aircraft

Abstract. Vertical distributions of atmospheric dimethyl sulfide (DMS(g)) were sampled aboard the research aircraft Polar 6 near Lancaster Sound, Nunavut, Canada in July 2014 and on pan-Arctic flights in April 2015 that started from Longyearbyen, Spitzbergen, and passed through Alert and Eureka, Nunavut and Inuvik, Northwest Territories. Larger mean DMS(g) mixing ratios were present during April 2015 (campaign-mean of 116±8 pptv) compared to July 2014 (campaign-mean of 20±6 pptv). Observations in July 2014 indicated a decrease in DMS(g) mixing ratios with altitude up to about 3 km, and the largest mixing ratios were found near the surface above ice-edge and open water, coincident with increased particle concentrations. In contrast, DMS(g) mixing ratios sampled in April 2015 were as high as 100 pptv near 2500 m. The April campaign also exhibited uniform campaign-mean vertical profiles overall although some profiles showed an increase with altitude. GEOS-Chem chemical-transport model simulations indicate that Arctic seawater (north of 66° N) contributes the majority of DMS(g) to the Arctic profiles (>90 %) in July 2014 flight tracks which were below 3000 m. More than 90 % of DMS(g) in April 2015 was from Arctic seawater for measurements below 500 m, but that declined to 60 % for altitudes between 500 m and 3000 m. FLEXPART simulations indicate that for summer 2014, the sampled air mass originated over Baffin Bay and the Canadian Arctic Archipelago. Whereas, for springtime 2015, the air mass sampled on flights near Alert and Eureka originated from Baffin Bay/Canadian Archipelago and from long-range transport (LRT) around the northern tip of Greenland. Our results highlight the role of open water below the flight as the source of DMS(g) during July 2014, and the influence of LRT of DMS(g) from further afield in the Arctic above 2500 m during April 2015.

scholarly journals Atmospheric VOC measurements at a High Arctic site: characteristics and source apportionment

2020 ◽  
Author(s):  
Jakob B. Pernov ◽  
Rossana Bossi ◽  
Thibaut Lebourgeois ◽  
Jacob K. Nøjgaard ◽  
Rupert Holzinger ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
High Arctic ◽  
Anthropogenic Sources ◽  
The Arctic ◽  
Back Trajectory ◽  
Research Station ◽  
Source Regions ◽  
Arctic Haze

Abstract. There are few long-term datasets of volatile organic compounds (VOCs) in the High Arctic. Furthermore, knowledge about their source regions remains lacking. To address this matter, we report a long-term dataset of highly time-resolved VOC measurements in the High Arctic from April to October 2018. We have utilized a combination of measurement and modeling techniques to characterize the mixing ratios, temporal patterns, and sources of VOCs at Villum Research Station at Station Nord, in Northeast Greenland. Atmospheric VOCs were measured using Proton Transfer-Time of Flight-Mass Spectrometry (PTR-ToF-MS). Ten ions were selected for source apportionment with the receptor model, positive matrix factorization (PMF). A four-factor solution to the PMF model was deemed optimal. The factors identified were Biomass Burning, Marine Cryosphere, Background, and Arctic Haze. The Biomass Burning factor described the variation of acetonitrile and benzene. Back trajectory analysis indicated the influence of active fires in North America and Eurasia. The Marine Cryosphere factor was comprised of carboxylic acids (formic, acetic, and propionic acid) as well as dimethyl sulfide (DMS). This factor displayed a clear diurnal profile during periods of snow and sea ice melt. Back trajectories showed that the source regions for this factor were the coasts around North Greenland and the Arctic Ocean. The Background factor was temporally ubiquitous, with a slight decrease in the summer. This factor was not driven by any individual chemical species. The Arctic Haze factor was dominated by benzene with contributions from oxygenated VOCs. This factor exhibited a maximum in the spring and minima during the summer and autumn. This temporal pattern and species profile are indicative of anthropogenic sources in the mid-latitudes. This study provides seasonal characteristics and sources of VOCs and can help elucidate the processes affecting the atmospheric chemistry and biogeochemical feedback mechanisms in the High Arctic.

scholarly journals Source Sector and Region Contributions to Black Carbon and PM<sub>2.5</sub> in the Arctic

2018 ◽  
Author(s):  
Negin Sobhani ◽  
Sarika Kulkarni ◽  
Gregory R. Carmichael
Keyword(s):  
Biomass Burning ◽  
Surface Concentration ◽  
The Arctic ◽  
Anthropogenic Emissions ◽  
Economic Sectors ◽  
Modeling Framework ◽  
Source Regions ◽  
Geographical Regions ◽  
Aircraft Observations ◽  
Pm2.5 Emissions

Abstract. The impacts of BC and PM2.5 emissions from different source sectors (e.g. transportation, power, industry, residential, and biomass burning) and source regions (e.g. Europe, North America, China, Russia, Central Asia, South Asia, and the Middle East) to Arctic BC and PM2.5 concentrations are investigated using a series of sensitivity runs with WRF-STEM modeling framework. The simulations are validated using aircraft observations over the Arctic during spring and summer 2008. Emissions from power, industrial, and biomass burning sectors are found to be the main contributors to the Arctic PM2.5 with contributions of ~ 30 %, ~ 25 %, and ~ 20 % respectively. In contrast, the residential and transportation sectors are identified as the major contributors to Arctic BC with contributions of ~ 38 % and ~ 30 %. Anthropogenic emissions are the most dominant contributors (~ 88 %) to the BC surface concentration over the Arctic; however, the contribution from biomass burning is significant over the summer (up to ~ 50 %). Among all geographical regions, Europe and China have the highest contributions to the BC surface concentrations with contributions of ~ 46 % and ~ 25 % respectively. Further sensitivity runs show that among various economic sectors of all geographic regions, European and Chinese residential sector contribute up to ~ 25 % and ~ 14 % to the Arctic average surface BC concentration. For Arctic PM2.5, the anthropogenic emissions contribute >~ 75 % at the surface annually, with contributions of ~ 25 % from Europe and ~ 20 % from China; however, the contributions of biomass burning emissions are significant in particular during spring and summer. The contributions of each geographical region to the Arctic PM2.5 and BC vary significantly with altitude. The simulations show that the BC from China is transported to the Arctic in the mid-troposphere, while, BC from European emission sources are transported near the surface under 5 km, especially during winter.

scholarly journals Ozone photochemistry in boreal biomass burning plumes

2013 ◽  
Vol 13 (15) ◽  
pp. 7321-7341 ◽  
Author(s):  
M. Parrington ◽  
P. I. Palmer ◽  
A. C. Lewis ◽  
J. D. Lee ◽  
A. R. Rickard ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Forest Fires ◽  
Dynamic Range ◽  
Ozone Production ◽  
The Arctic ◽  
Aircraft Measurements ◽  
Alkyl Nitrates ◽  
Mixing Ratios ◽  
Aerosol Loading ◽  
The Impact

Abstract. We present an analysis of ozone (O3) photochemistry observed by aircraft measurements of boreal biomass burning plumes over eastern Canada in the summer of 2011. Measurements of O3 and a number of key chemical species associated with O3 photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the "quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS) experiment between 12 July and 3 August 2011. The location and timing of the aircraft measurements put BORTAS into a unique position to sample biomass burning plumes from the same source region in Northwestern Ontario with a range of ages. We found that O3 mixing ratios measured in biomass burning plumes were indistinguishable from non-plume measurements, but evaluating them in relationship to measurements of carbon monoxide (CO), total alkyl nitrates (ΣAN) and the surrogate species NOz (= NOy-NOx) revealed that the potential for O3 production increased with plume age. We used NMHC ratios to estimate photochemical ages of the observed biomass burning plumes between 0 and 10 days. The BORTAS measurements provided a wide dynamic range of O3 production in the sampled biomass burning plumes with ΔO3/ΔCO enhancement ratios increasing from 0.020 ± 0.008 ppbv ppbv−1 in plumes with photochemical ages less than 2 days to 0.55 ± 0.29 ppbv ppbv−1 in plumes with photochemical ages greater than 5 days. We found that the main contributing factor to the variability in the ΔO3/ΔCO enhancement ratio was ΔCO in plumes with photochemical ages less than 4 days, and that was a transition to ΔO3 becoming the main contributing factor in plumes with ages greater than 4 days. In comparing O3 mixing ratios with components of the NOy budget, we observed that plumes with ages between 2 and 4 days were characterised by high aerosol loading, relative humidity greater than 40%, and low ozone production efficiency (OPE) of 7.7 ± 3.5 ppbv ppbv−1 relative to ΣAN and 1.6 ± 0.9 ppbv ppbv−1 relative to NOz. In plumes with ages greater than 4 days, OPE increased to 472 ± 28 ppbv ppbv−1 relative to ΣAN and 155 ± 5 ppbv ppbv−1 relative to NOz. From the BORTAS measurements we estimated that aged plumes with low aerosol loading were close to being in photostationary steady state and O3 production in younger plumes was inhibited by high aerosol loading and greater production of ΣAN relative to O3. The BORTAS measurements of O3 photochemistry in boreal biomass burning plumes were found to be consistent with previous summertime aircraft measurements made over the same region during the Arctic Research of the Composition of the Troposphere (ARCTAS-B) in 2008 and Atmospheric Boundary Layer Experiment (ABLE 3B) in 1990.

scholarly journals Analysis of atmospheric CH<sub>4</sub> in Canadian Arctic and estimation of the regional CH<sub>4</sub> fluxes

2018 ◽  
Author(s):  
Misa Ishizawa ◽  
Douglas Chan ◽  
Doug Worthy ◽  
Elton Chan ◽  
Felix Vogel ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Canadian Arctic ◽  
Weather Conditions ◽  
Temporal Variations ◽  
The Arctic ◽  
Atmospheric Methane ◽  
Ch4 Emissions ◽  
Annual Variations ◽  
Source Regions ◽  
Long Term Trends

Abstract. The Canadian Arctic has the potential for enhanced atmospheric methane (CH4) source regions as a response to the ongoing global warming. Current bottom-up and top-down estimates of the regional CH4 flux range widely. This study analyses the recent observations of atmospheric CH4 from five arctic monitoring sites and presents estimates of the regional CH4 fluxes for 2012–2015. The observational data reveal sizeable synoptic summertime enhancements in the atmospheric CH4 that are clearly distinguishable from background variations, which indicate strong regional fluxes (mainly wetland and biomass burning CH4 emissions) around Behchoko and Inuvik in the western Canadian Arctic. Multiple regional Bayesian inversion modelling systems are applied to estimate fluxes for the entire Canadian Arctic and show relatively robust results in amplitude and temporal variations even across different transport models, prior fluxes and sub-region masking. The estimated mean total CH4 annual flux for the Canadian Arctic is 1.8 ± 0.6 Tg CH4 yr−1. The flux estimate in this study is partitioned into biomass burning, 0.3 ± 0.1 Tg CH4 yr−1, and the remaining natural (wetland) flux 1.5 ± 0.5 Tg CH4 yr−1. The estimated summertime natural CH4 fluxes show clear inter-annual variability that is positively correlated with surface temperature anomalies. This indicates that the hot summer weather conditions stimulate the wetland CH4 emissions. More data and analysis are required to statistically characterise the dependence of regional CH4 fluxes on climate in the Arctic. These Arctic measurement sites should help quantify the inter-annual variations and long-term trends in CH4 emissions in the Canadian Arctic.

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