Do contemporary (1980–2015) emissions determine the elemental carbon deposition trend at Holtedahlfonna glacier, Svalbard?

Abstract. The climate impact of black carbon (BC) is notably amplified in the Arctic by its deposition, which causes albedo decrease and subsequent earlier snow and ice spring melt. To comprehensively assess the climate impact of BC in the Arctic, information on both atmospheric BC concentrations and deposition is essential. Currently, Arctic BC deposition data are very scarce, while atmospheric BC concentrations have been shown to generally decrease since the 1990s. However, a 300-year Svalbard ice core showed a distinct increase in EC (elemental carbon, proxy for BC) deposition from 1970 to 2004 contradicting atmospheric measurements and modelling studies. Here, our objective was to decipher whether this increase has continued in the 21st century and to investigate the drivers of the observed EC deposition trends. For this, a shallow firn core was collected from the same Svalbard glacier, and a regional-to-meso-scale chemical transport model (SILAM) was run from 1980 to 2015. The ice and firn core data indicate peaking EC deposition values at the end of the 1990s and lower values thereafter. The modelled BC deposition results generally support the observed glacier EC variations. However, the ice and firn core results clearly deviate from both measured and modelled atmospheric BC concentration trends, and the modelled BC deposition trend shows variations seemingly independent from BC emission or atmospheric BC concentration trends. Furthermore, according to the model ca. 99 % BC mass is wet-deposited at this Svalbard glacier, indicating that meteorological processes such as precipitation and scavenging efficiency have most likely a stronger influence on the BC deposition trend than BC emission or atmospheric concentration trends. BC emission source sectors contribute differently to the modelled atmospheric BC concentrations and BC deposition, which further supports our conclusion that different processes affect atmospheric BC concentration and deposition trends. Consequently, Arctic BC deposition trends should not directly be inferred based on atmospheric BC measurements, and more observational BC deposition data are required to assess the climate impact of BC in Arctic snow.

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Do contemporary (1980–2015) emissions determine the elemental carbon deposition trend at Holtedahlfonna glacier, Svalbard?

10.5194/acp-2017-357 ◽

2017 ◽

Author(s):

Meri M. Ruppel ◽

Joana Soares ◽

Jean-Charles Gallet ◽

Elisabeth Isaksson ◽

Tõnu Martma ◽

...

Keyword(s):

Elemental Carbon ◽

Transport Model ◽

Ice Core ◽

Climate Impact ◽

The Arctic ◽

Chemical Transport Model ◽

Atmospheric Measurements ◽

Atmospheric Concentration ◽

Scavenging Efficiency ◽

Firn Core

Abstract. The climate impact of black carbon (BC) is notably amplified in the Arctic by its deposition that causes albedo decrease and subsequent earlier snow and ice spring melt. To comprehensively assess the climate impact of BC in the Arctic, information on both atmospheric BC concentrations and deposition are essential. Currently, Arctic BC deposition data are very scarce, while atmospheric BC concentrations have been shown to generally decrease since the 1990s. However, a 300-year Svalbard ice core showed a distinct increase in EC (elemental carbon, proxy for BC) deposition from 1970 to 2004 contradicting atmospheric measurements and modelling studies. Here, our objective was to decipher whether this increase has continued in the 21st century, and to investigate the drivers of the observed EC deposition trends. For this, a shallow firn core was collected from the same Svalbard glacier, and a regional-to-meso-scale chemical transport model (SILAM) was run from 1980 to 2015. The ice and firn core data indicate peaking EC deposition values at the end of the 1990s, and lower values thereafter. The modelled BC deposition results generally support the observed glacier EC variations. However, the ice and firn core results clearly deviate from both measured and modelled atmospheric BC concentration trends, and the modelled BC deposition trend shows variations seemingly independent from BC emission or atmospheric BC concentration trends. Furthermore, ca. 99 % BC mass is wet-deposited at this Svalbard glacier, indicating that meteorological processes such as precipitation and scavenging efficiency have most likely a stronger influence on the BC deposition trend than BC emission or atmospheric concentration trends. BC emission source sectors contribute differently to the modelled atmospheric BC concentrations and BC deposition, which further supports our conclusion that different processes affect atmospheric BC concentration and deposition trends. Consequently, Arctic BC deposition trends should not directly be inferred based on atmospheric BC measurements, and more observational BC deposition data are required to assess the climate impact of BC in Arctic snow.

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Effects of Wegener-Bergeron-Findeisen Process on Global Black Carbon Distribution

10.5194/acp-2016-706 ◽

2016 ◽

Cited By ~ 1

Author(s):

Ling Qi ◽

Qinbin Li ◽

Cenlin He ◽

Xin Wang ◽

Jianping Huang

Keyword(s):

Transport Model ◽

Liquid Water Content ◽

Mixed Phase ◽

The Arctic ◽

Deposition Flux ◽

Chemical Transport Model ◽

Washout Ratio ◽

Lower Temperature ◽

Mixed Phase Clouds ◽

Scavenging Efficiency

Abstract. We systematically investigate the effects of Wegener-Bergeron-Findeisen (WBF) on BC scavenging efficiency, surface BCair, deposition flux, concentration in snow (BCsnow, ng g−1), and washout ratio using a global 3D chemical transport model (GEOS-Chem). We differentiate riming- versus WBF-dominated in-cloud scavenging based on liquid water content (LWC) and temperature. Specifically, we relate WBF to either temperature or ice mass fraction (IMF) in mixed-phase clouds. We find that at Jungfraujoch, Switzerland and Abisko, Sweden, where WBF dominates, the discrepancies of simulated BC scavenging efficiency and washout ratio are significantly reduced (from a factor of 3 to 10 % and from a factor of 4–5 to a factor of two). However, at Zeppelin, Norway, where riming dominates, simulation of BC scavenging efficiency, BCair, and washout ratio become worse (relative to observations) when WBF is included. There is thus an urgent need for extensive observations to distinguish and characterize riming- versus WBF-dominated aerosol scavenging in mixed-phase clouds and the associated BC scavenging efficiency. We find the reduction resulting from WBF to global BC scavenging efficiency varies substantially, from 8 % in the tropics to 76 % in the Arctic. The resulting annual mean BCair increases by up to 156 % at high altitudes and at northern high latitudes because of lower temperature and higher IMF. Overall, WBF halves the model-observation discrepancy (from −65 % to −30 %) of BCair across North America, Europe, China and the Arctic. Globally WBF increases BC burden from 0.22 to 0.29–0.35 mg m−2 yr−1, which partially explains the gap between observed and previous model simulated BC burdens over land. In addition, WBF significantly increases BC lifetime from 5.7 days to ~8 days. Additionally, WBF results in a significant redistribution of BC deposition in source and remote regions. Specifically, it lowers BC wet deposition (by 37–63 % at northern mid-latitudes and by 21–29 % in the Arctic) while increases dry deposition (by 3–16 % at mid-latitudes and by 81–159 % in the Arctic). The resulting total BC deposition is lower at mid-latitudes (by 12–34 %) but higher in the Arctic (by 2–29 %). We find that WBF decreases BCsnow at mid-latitudes (by ~15 %) but increases it in the Arctic (by 26 %) while improving model comparisons with observations. In addition, WBF dramatically reduces the model-observation discrepancy of washout ratios in winter (from a factor of 16 to 4). The remaining discrepancies in BCair, BCsnow and BC washout ratios suggest that in-cloud removal in mixed-phased clouds is likely still excessive over land.

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Effects of the Wegener–Bergeron–Findeisen process on global black carbon distribution

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-7459-2017 ◽

2017 ◽

Vol 17 (12) ◽

pp. 7459-7479 ◽

Cited By ~ 15

Author(s):

Ling Qi ◽

Qinbin Li ◽

Cenlin He ◽

Xin Wang ◽

Jianping Huang

Keyword(s):

Black Carbon ◽

Transport Model ◽

Mixed Phase ◽

The Arctic ◽

Deposition Flux ◽

Chemical Transport Model ◽

Washout Ratio ◽

Cloud Scavenging ◽

Mixed Phase Clouds ◽

Scavenging Efficiency

Abstract. We systematically investigate the effects of Wegener–Bergeron–Findeisen process (hereafter WBF) on black carbon (BC) scavenging efficiency, surface BCair, deposition flux, concentration in snow (BCsnow, ng g−1), and washout ratio using a global 3-D chemical transport model (GEOS-Chem). We differentiate riming- versus WBF-dominated in-cloud scavenging based on liquid water content (LWC) and temperature. Specifically, we implement an implied WBF parameterization using either temperature or ice mass fraction (IMF) in mixed-phase clouds based on field measurements. We find that at Jungfraujoch, Switzerland, and Abisko, Sweden, where WBF dominates in-cloud scavenging, including the WBF effect strongly reduces the discrepancies of simulated BC scavenging efficiency and washout ratio against observations (from a factor of 3 to 10 % and from a factor of 4–5 to a factor of 2). However, at Zeppelin, Norway, where riming dominates, simulation of BC scavenging efficiency, BCair, and washout ratio become worse (relative to observations) when WBF is included. There is thus an urgent need for extensive observations to distinguish and characterize riming- versus WBF-dominated aerosol scavenging in mixed-phase clouds and the associated BC scavenging efficiency. Our model results show that including the WBF effect lowers global BC scavenging efficiency, with a higher reduction at higher latitudes (8 % in the tropics and up to 76 % in the Arctic). The resulting annual mean BCair increases by up to 156 % at high altitudes and at northern high latitudes because of lower temperature and higher IMF. Overall, WBF halves the model–observation discrepancy (from −65 to −30 %) of BCair across North America, Europe, China and the Arctic. Globally WBF increases BC burden from 0.22 to 0.29–0.35 mg m−2 yr−1, which partially explains the gap between observed and previous model-simulated BC burdens over land. In addition, WBF significantly increases BC lifetime from 5.7 to ∼  8 days. Additionally, WBF results in a significant redistribution of BC deposition in source and remote regions. Specifically, it lowers BC wet deposition (by 37–63 % at northern mid-latitudes and by 21–29 % in the Arctic), while it increases dry deposition (by 3–16 % at mid-latitudes and by 81–159 % in the Arctic). The resulting total BC deposition is lower at mid-latitudes (by 12–34 %) but higher in the Arctic (by 2–29 %). We find that WBF decreases BCsnow at mid-latitudes (by ∼  15 %) but increases it in the Arctic (by 26 %) while improving model comparisons with observations. In addition, WBF dramatically reduces the model–observation discrepancy of washout ratios in winter (from a factor of 16 to 4). The remaining discrepancies in BCair, BCsnow and BC washout ratios suggest that in-cloud removal in mixed-phased clouds is likely still excessive over land.

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The sensitivity of the oxygen isotopes of ice core sulfate to changing oxidant concentrations since the preindustrial

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-20607-2010 ◽

2010 ◽

Vol 10 (8) ◽

pp. 20607-20623 ◽

Cited By ~ 2

Author(s):

E. D. Sofen ◽

B. Alexander ◽

S. A. Kunasek

Keyword(s):

Oxygen Isotopes ◽

Radiative Forcing ◽

Transport Model ◽

Ice Core ◽

Ice Cores ◽

The Arctic ◽

Aerosol Formation ◽

Chemical Transport Model ◽

Sensitivity Studies ◽

Sulfate Formation

Abstract. Changes in tropospheric oxidant concentrations since preindustrial times have implications for the ozone radiative forcing, lifetimes of reduced trace gases, aerosol formation, and human health but are highly uncertain. Measurements of the triple oxygen isotopes of sulfate in ice cores (described by Δ17OSO4 = δ17O − 0.52 × δ18O) provide one of the few constraints on paleo-oxidants. We use the GEOS-Chem global atmospheric chemical transport model to simulate changes in oxidant concentrations and the Δ17OSO4 between 1850 and 1990 to assess the sensitivity of Δ17OSO4 measurements in Greenland and Antarctic ice cores to changing tropospheric oxidant concentrations. The model indicates a 42% increase in the concentration of global mean tropospheric O3, a 10% decrease in OH, and a 58% increase in H2O2 between the preindustrial and present. Modeled Δ17OSO4 is consistent with measurements from ice core and aerosol samples. Model results indicate that the observed decrease in the Arctic Δ17OSO4 in spite of increasing O3 is due to the combined effects of increased sulfate formation by O2 catalyzed by anthropogenic transition metals and increased cloud water acidity. In Antarctica, the Δ17OSO4 is sensitive to relative changes of oxidant concentrations, but in a nonlinear fashion. Sensitivity studies explore the uncertainties in preindustrial emissions of oxidant precursors.

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Unexpected increase in elemental carbon values over the last 30 years observed in a Svalbard ice core

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-13197-2014 ◽

2014 ◽

Vol 14 (9) ◽

pp. 13197-13231

Author(s):

M. M. Ruppel ◽

E. Isaksson ◽

J. Ström ◽

E. Beaudon ◽

J. Svensson ◽

...

Keyword(s):

Elemental Carbon ◽

Ice Core ◽

Ice Cores ◽

The Arctic ◽

Radiative Energy ◽

Atmospheric Measurements ◽

The Past ◽

Depositional Processes ◽

Quartz Fibre ◽

Ice Core Records

Abstract. Black carbon (BC) is a light-absorbing particle that warms the atmosphere–Earth system. The climate effects of BC are amplified in the Arctic where its deposition on light surfaces decreases the albedo and causes earlier melt of snow and ice. Despite its suggested significant role in Arctic climate warming there is little information on BC concentrations and deposition in the past. Here we present results on BC (here operationally defined as elemental carbon (EC)) concentrations and deposition on a Svalbard glacier between 1700 and 2004. The inner part of a 125 m deep ice core from Holtedahlfonna glacier (79°8' N, 13°16' E, 1150 m a.s.l.) was melted, filtered through a quartz fibre filter and analysed for EC using a thermal optical method. The EC values started to increase after 1850 and peaked around 1910, similar to ice core records from Greenland. Strikingly, the EC values again increase rapidly between 1970 and 2004. This rise is not seen in Greenland ice cores and it seems to contradict atmospheric BC measurements indicating generally decreasing atmospheric BC concentrations since 1989 in the Arctic. Several hypotheses, such as changes in scavenging efficiencies, post-depositional processes and differences in the vertical distribution of BC in the atmosphere, are discussed for the differences between the Svalbard and Greenland ice core records, and the ice core and atmospheric measurements in Svalbard. In addition, the divergent BC trends between Greenland and Svalbard ice cores may be caused by differences in the analytical methods used, including the operational definitions of quantified particles, and detection efficiencies of different-sized BC particles. Regardless of the cause of the increasing EC values in the recent decades, the results have significant implications for the past radiative energy balance at the coring site.

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Increase in elemental carbon values between 1970 and 2004 observed in a 300-year ice core from Holtedahlfonna (Svalbard)

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-11447-2014 ◽

2014 ◽

Vol 14 (20) ◽

pp. 11447-11460 ◽

Cited By ~ 21

Author(s):

M. M. Ruppel ◽

E. Isaksson ◽

J. Ström ◽

E. Beaudon ◽

J. Svensson ◽

...

Keyword(s):

Elemental Carbon ◽

Ice Core ◽

Ice Cores ◽

The Arctic ◽

Radiative Energy ◽

Atmospheric Measurements ◽

The Past ◽

Depositional Processes ◽

Quartz Fibre ◽

Ice Core Records

Abstract. Black carbon (BC) is a light-absorbing particle that warms the atmosphere–Earth system. The climate effects of BC are amplified in the Arctic, where its deposition on light surfaces decreases the albedo and causes earlier melt of snow and ice. Despite its suggested significant role in Arctic climate warming, there is little information on BC concentrations and deposition in the past. Here we present results on BC (here operationally defined as elemental carbon (EC)) concentrations and deposition on a Svalbard glacier between 1700 and 2004. The inner part of a 125 m deep ice core from Holtedahlfonna glacier (79°8' N, 13°16' E, 1150 m a.s.l.) was melted, filtered through a quartz fibre filter and analysed for EC using a thermal–optical method. The EC values started to increase after 1850 and peaked around 1910, similar to ice core records from Greenland. Strikingly, the EC values again increase rapidly between 1970 and 2004 after a temporary low point around 1970, reaching unprecedented values in the 1990s. This rise is not seen in Greenland ice cores, and it seems to contradict atmospheric BC measurements indicating generally decreasing atmospheric BC concentrations since 1989 in the Arctic. For example, changes in scavenging efficiencies, post-depositional processes and differences in the vertical distribution of BC in the atmosphere are discussed for the differences between the Svalbard and Greenland ice core records, as well as the ice core and atmospheric measurements in Svalbard. In addition, the divergent BC trends between Greenland and Svalbard ice cores may be caused by differences in the analytical methods used, including the operational definitions of quantified particles, and detection efficiencies of different-sized BC particles. Regardless of the cause of the increasing EC values between 1970 and 2004, the results have significant implications for the past radiative energy balance at the coring site.

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Record springtime stratospheric ozone depletion at 80°N in 2020

10.5194/egusphere-egu21-8892 ◽

2021 ◽

Author(s):

Ramina Alwarda ◽

Kristof Bognar ◽

Kimberly Strong ◽

Martyn Chipperfield ◽

Sandip Dhomse ◽

...

Keyword(s):

Ozone Depletion ◽

Transport Model ◽

Stratospheric Ozone ◽

Polar Vortex ◽

The Arctic ◽

Optical Absorption Spectroscopy ◽

Chemical Transport Model ◽

Polar Stratospheric Clouds ◽

Ozone Loss ◽

Stratospheric Clouds

The Arctic winter of 2019-2020 was characterized by an unusually persistent polar vortex and temperatures in the lower stratosphere that were consistently below the threshold for the formation of polar stratospheric clouds (PSCs). These conditions led to ozone loss that is comparable to the Antarctic ozone hole. Ground-based measurements from a suite of instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05&#176;N, 86.42&#176;W) were used to investigate chemical ozone depletion. The vortex was located above Eureka longer than in any previous year in the 20-year dataset and lidar measurements provided evidence of polar stratospheric clouds (PSCs) above Eureka. Additionally, UV-visible zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements showed record ozone loss in the 20-year dataset, evidence of denitrification along with the slowest increase of NO2 during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO2 (chlorine reservoir species) from a Fourier transform infrared (FTIR) spectrometer showed unusually low columns that were comparable to 2011, the previous year with significant chemical ozone depletion. Record low values of HNO3 in the FTIR dataset are in accordance with the evidence of PSCs and a denitrified atmosphere. Estimates of chemical ozone loss were derived using passive ozone from the SLIMCAT offline chemical transport model to account for dynamical contributions to the stratospheric ozone budget.

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Record-breaking ozone loss in the Arctic winter 2010/2011: comparison with 1996/1997

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-7073-2012 ◽

2012 ◽

Vol 12 (15) ◽

pp. 7073-7085 ◽

Cited By ~ 34

Author(s):

J. Kuttippurath ◽

S. Godin-Beekmann ◽

F. Lefèvre ◽

G. Nikulin ◽

M. L. Santee ◽

...

Keyword(s):

Transport Model ◽

Chemical Transport ◽

The Arctic ◽

Altitude Range ◽

Chemical Transport Model ◽

Model Simulations ◽

Ozone Loss ◽

Elevated Ozone ◽

Record Value ◽

First Time

Abstract. We present a detailed discussion of the chemical and dynamical processes in the Arctic winters 1996/1997 and 2010/2011 with high resolution chemical transport model (CTM) simulations and space-based observations. In the Arctic winter 2010/2011, the lower stratospheric minimum temperatures were below 195 K for a record period of time, from December to mid-April, and a strong and stable vortex was present during that period. Simulations with the Mimosa-Chim CTM show that the chemical ozone loss started in early January and progressed slowly to 1 ppmv (parts per million by volume) by late February. The loss intensified by early March and reached a record maximum of ~2.4 ppmv in the late March–early April period over a broad altitude range of 450–550 K. This coincides with elevated ozone loss rates of 2–4 ppbv sh−1 (parts per billion by volume/sunlit hour) and a contribution of about 30–55% and 30–35% from the ClO-ClO and ClO-BrO cycles, respectively, in late February and March. In addition, a contribution of 30–50% from the HOx cycle is also estimated in April. We also estimate a loss of about 0.7–1.2 ppmv contributed (75%) by the NOx cycle at 550–700 K. The ozone loss estimated in the partial column range of 350–550 K exhibits a record value of ~148 DU (Dobson Unit). This is the largest ozone loss ever estimated in the Arctic and is consistent with the remarkable chlorine activation and strong denitrification (40–50%) during the winter, as the modeled ClO shows ~1.8 ppbv in early January and ~1 ppbv in March at 450–550 K. These model results are in excellent agreement with those found from the Aura Microwave Limb Sounder observations. Our analyses also show that the ozone loss in 2010/2011 is close to that found in some Antarctic winters, for the first time in the observed history. Though the winter 1996/1997 was also very cold in March–April, the temperatures were higher in December–February, and, therefore, chlorine activation was moderate and ozone loss was average with about 1.2 ppmv at 475–550 K or 42 DU at 350–550 K, as diagnosed from the model simulations and measurements.

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Detectability of Arctic methane sources at six sites performing continuous atmospheric measurements

10.5194/acp-2017-169 ◽

2017 ◽

Cited By ~ 1

Author(s):

Thibaud Thonat ◽

Marielle Saunois ◽

Philippe Bousquet ◽

Isabelle Pison ◽

Zeli Tan ◽

...

Keyword(s):

Land Surface ◽

Transport Model ◽

Land Surface Model ◽

Arctic Region ◽

The Arctic ◽

Surface Model ◽

Multiple Sources ◽

Atmospheric Measurements ◽

Methane Cycle ◽

Methane Budget

Abstract. Understanding the recent evolution of methane emissions in the Arctic is necessary to interpret the global methane cycle. Emissions are affected by significant uncertainties and are sensitive to climate change, leading to potential feedbacks. A polar version of the CHIMERE chemistry-transport model is used to simulate the evolution of tropospheric methane in the Arctic during 2012, including all known regional anthropogenic and natural sources. CHIMERE simulations are compared to atmospheric continuous observations at six measurement sites in the Arctic region. In winter, the Arctic is dominated by anthropogenic emissions; emissions from continental seepages and oceans, including from the East Siberian Arctic Shelf, can contribute significantly in more limited areas. In summer, emissions from wetland and freshwater sources dominate across the whole region. The model is able to reproduce the seasonality and synoptic variations of methane measured at the different sites. We find that all methane sources significantly affect the measurements at all stations at least at the synoptic scale, except for biomass burning; this indicates the relevance of continuous observations to gain a mechanistic understanding of Arctic methane sources. Sensitivity tests reveal that the choice of the land surface model used to prescribe wetland emissions can be critical in correctly representing methane concentrations. Also testing different freshwater emission inventories leads to large differences in modelled methane. Attempts to include methane sinks (OH oxidation and soil uptake) reduced the model bias relative to observed atmospheric CH4. The study illustrates how multiple sources, having different spatiotemporal dynamics and magnitudes, jointly influence the overall Arctic methane budget, and highlights ways towards further improved assessments.

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Source attribution of Arctic black carbon constrained by aircraft and surface measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-11971-2017 ◽

2017 ◽

Vol 17 (19) ◽

pp. 11971-11989 ◽

Cited By ~ 30

Author(s):

Jun-Wei Xu ◽

Randall V. Martin ◽

Andrew Morrow ◽

Sangeeta Sharma ◽

Lin Huang ◽

...

Keyword(s):

North America ◽

Biomass Burning ◽

Western Siberia ◽

Transport Model ◽

Chemical Transport ◽

The Arctic ◽

Anthropogenic Emissions ◽

Chemical Transport Model ◽

Northern Asia ◽

Airborne Measurements

Abstract. Black carbon (BC) contributes to Arctic warming, yet sources of Arctic BC and their geographic contributions remain uncertain. We interpret a series of recent airborne (NETCARE 2015; PAMARCMiP 2009 and 2011 campaigns) and ground-based measurements (at Alert, Barrow and Ny-Ålesund) from multiple methods (thermal, laser incandescence and light absorption) with the GEOS-Chem global chemical transport model and its adjoint to attribute the sources of Arctic BC. This is the first comparison with a chemical transport model of refractory BC (rBC) measurements at Alert. The springtime airborne measurements performed by the NETCARE campaign in 2015 and the PAMARCMiP campaigns in 2009 and 2011 offer BC vertical profiles extending to above 6 km across the Arctic and include profiles above Arctic ground monitoring stations. Our simulations with the addition of seasonally varying domestic heating and of gas flaring emissions are consistent with ground-based measurements of BC concentrations at Alert and Barrow in winter and spring (rRMSE  < 13 %) and with airborne measurements of the BC vertical profile across the Arctic (rRMSE  = 17 %) except for an underestimation in the middle troposphere (500–700 hPa).Sensitivity simulations suggest that anthropogenic emissions in eastern and southern Asia have the largest effect on the Arctic BC column burden both in spring (56 %) and annually (37 %), with the largest contribution in the middle troposphere (400–700 hPa). Anthropogenic emissions from northern Asia contribute considerable BC (27 % in spring and 43 % annually) to the lower troposphere (below 900 hPa). Biomass burning contributes 20 % to the Arctic BC column annually.At the Arctic surface, anthropogenic emissions from northern Asia (40–45 %) and eastern and southern Asia (20–40 %) are the largest BC contributors in winter and spring, followed by Europe (16–36 %). Biomass burning from North America is the most important contributor to all stations in summer, especially at Barrow.Our adjoint simulations indicate pronounced spatial heterogeneity in the contribution of emissions to the Arctic BC column concentrations, with noteworthy contributions from emissions in eastern China (15 %) and western Siberia (6.5 %). Although uncertain, gas flaring emissions from oilfields in western Siberia could have a striking impact (13 %) on Arctic BC loadings in January, comparable to the total influence of continental Europe and North America (6.5 % each in January). Emissions from as far as the Indo-Gangetic Plain could have a substantial influence (6.3 % annually) on Arctic BC as well.

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