scholarly journals Contrasting source contributions of Arctic black carbon to atmospheric concentrations, deposition flux, and atmospheric and snow radiative effects

2022 ◽  
Author(s):  
Hitoshi Matsui ◽  
Tatsuhiro Mori ◽  
Sho Ohata ◽  
Nobuhiro Moteki ◽  
Naga Oshima ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Black Carbon ◽  
Seasonal Variations ◽  
Climate Impacts ◽  
The Arctic ◽  
Deposition Flux ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Source Contributions ◽  
Mass Concentrations

Abstract. Black carbon (BC) particles in the Arctic contribute to rapid warming of the Arctic by heating the atmosphere and snow and ice surfaces. Understanding the source contributions to Arctic BC is therefore important, but they are not well understood, especially those for atmospheric and snow radiative effects. Here we estimate simultaneously the source contributions of Arctic BC to near-surface and vertically integrated atmospheric BC mass concentrations (MBC_SRF and MBC_COL), BC deposition flux (MBC_DEP), and BC radiative effects at the top of the atmosphere and snow surface (REBC_TOA and REBC_SNOW), and show that the source contributions to these five variables are highly different. In our estimates, Siberia makes the largest contribution to MBC_SRF, MBC_DEP, and REBC_SNOW in the Arctic (defined as > 70° N), accounting for 70 %, 53 %, and 43 %, respectively. In contrast, Asia’s contributions to MBC_COL and REBC_TOA are largest, accounting for 38 % and 45 %, respectively. In addition, the contributions of biomass burning sources are larger (24−34 %) to MBC_DEP, REBC_TOA, and REBC_SNOW, which are highest from late spring to summer, and smaller (4.2−14 %) to MBC_SRF and MBC_COL, whose concentrations are highest from winter to spring. These differences in source contributions to these five variables are due to seasonal variations in BC emission, transport, and removal processes and solar radiation, as well as to differences in radiative effect efficiency (radiative effect per unit BC mass) among sources. Radiative effect efficiency varies by a factor of up to 4 among sources (1465−5439 W g–1) depending on lifetimes, mixing states, and heights of BC and seasonal variations of emissions and solar radiation. As a result, source contributions to radiative effects and mass concentrations (i.e., REBC_TOA and MBC_COL, respectively) are substantially different. The results of this study demonstrate the importance of considering differences in the source contributions of Arctic BC among mass concentrations, deposition, and atmospheric and snow radiative effects for accurate understanding of Arctic BC and its climate impacts.

scholarly journals Radiative Effect and Climate Impacts of Brown Carbon with the Community Atmosphere Model (CAM5)

2018 ◽  
Author(s):  
Hunter Brown ◽  
Xiaohong Liu ◽  
Yan Feng ◽  
Yiquan Jiang ◽  
Mingxuan Wu ◽  
...  
Keyword(s):  
Model Comparison ◽  
Climate Impacts ◽  
The Arctic ◽  
Radiation Absorption ◽  
Wave Radiation ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Brown Carbon ◽  
Community Atmosphere Model ◽  
Atmosphere Model

Abstract. A recent development in the representation of aerosols in climate models is the realization that some components of organic aerosol (OA), emitted from biomass and biofuel burning, can have a significant contribution to short-wave radiation absorption in the atmosphere. The absorbing fraction of OA is referred to as brown carbon (BrC). This study introduces one of the first implementations of BrC into the Community Atmosphere Model version 5 (CAM5), using a parameterization for BrC absorptivity described in Saleh et al. (2014). 9-year experiments are run (2003–2011) with prescribed emissions and sea surface temperatures to analyze the effect of BrC in the atmosphere. Model validation is conducted via model comparison to single-scatter albedo and aerosol optical depth from the Aerosol Robotic Network (AERONET). This comparison reveals a model underestimation of SSA in biomass burning regions for both default and BrC model runs, while a comparison between AERONET and model absorption Angstrom exponent shows a marked improvement with BrC implementation. Global annual average radiative effects are calculated due to aerosol-radiation interactions (REari; 0.13 ± 0.01 W m−2) and aerosol-cloud interactions (REaci; 0.01 ± 0.04 W m−2). REari is similar to other studies' estimations of BrC direct radiative effect, while REaci indicates a global reduction in low clouds due to the BrC semi-direct effect. The mechanisms for these physical changes are investigated and found to correspond with changes in global circulation patterns. Comparisons of BrC implementation approaches find that this implementation predicts a lower BrC REari in the Arctic regions than previous studies with CAM5. Implementation of BrC bleaching effect shows a significant reduction in REari (0.06 ± 0.008 W m−2). Also, variations in OA density can lead to differences in REari and REaci, indicating the importance of specifying this property when estimating the BrC radiative effects and when comparing similar studies.

scholarly journals The importance of the representation of air pollution emissions for the modeled distribution and radiative effects of black carbon in the Arctic

2019 ◽  
Author(s):  
Jacob Schacht ◽  
Bernd Heinold ◽  
Johannes Quaas ◽  
John Backman ◽  
Ribu Cherian ◽  
...  
Keyword(s):  
Air Pollution ◽  
Black Carbon ◽  
Current Model ◽  
The Arctic ◽  
Radiation Balance ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Near Surface ◽  
Pollution Emissions ◽  
Air Pollution Emissions

Abstract. Aerosol particles can contribute to the Arctic Amplification by direct and indirect radiative effects. Specifically, black carbon (BC) in the atmosphere, and when deposited on snow and sea ice, has a positive effect on the top of atmosphere radiation balance during polar day. Current climate models, however, are still struggling to reproduce Arctic aerosol conditions. We present an evaluation study with the global aerosol-climate model ECHAM6.3-HAM2.3 to examine emission-related uncertainties in the BC distribution and the direct radiative effect of BC. The model results are comprehensively compared against latest ground and air-borne aerosol observations for the period 2005–2017 with focus on BC. Four different setups of air pollution emissions are tested. The simulations in general match well with the observed amount and temporal variability of near-surface BC in the Arctic. Using actual daily instead of fixed biomass burning emissions is crucial to reproduce individual pollution events but has only a small influence on the seasonal cycle of BC. Compared to commonly used fixed anthropogenic emissions for the year 2000, an up-to-date inventory with transient air pollution emissions results in up to 30 % higher annual BC burden and an over 0.2 W m−2 higher annual mean all-sky net direct radiative effect of BC at top of the atmosphere over the Eastern Arctic Ocean. We estimate BC in the Arctic to lead to a net gain of up 0.8 W m−2 by the direct radiative effect of atmospheric BC plus the effect by an albedo reduction by BC-in-snow. Long-range transport is identified as one of the main sources of uncertainties for ECHAM6.3-HAM2.3, leading to an overestimation of BC in atmospheric layers above 500 hPa especially in summer. This is related to a misrepresentation in wet removal in one identified case at least, that was observed during the ARCTAS summer aircraft campaign. Over all, the current model version has significantly improved since previous intercomparison studies and performs now better than the AeroCom average in terms of the spatial and temporal distribution of Arctic BC.

scholarly journals Radiative effect and climate impacts of brown carbon with the Community Atmosphere Model (CAM5)

2018 ◽  
Vol 18 (24) ◽  
pp. 17745-17768 ◽  
Author(s):  
Hunter Brown ◽  
Xiaohong Liu ◽  
Yan Feng ◽  
Yiquan Jiang ◽  
Mingxuan Wu ◽  
...  
Keyword(s):  
Model Comparison ◽  
Climate Impacts ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Radiation Absorption ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Brown Carbon ◽  
Community Atmosphere Model ◽  
Atmosphere Model

Abstract. A recent development in the representation of aerosols in climate models is the realization that some components of organic aerosol (OA), emitted from biomass and biofuel burning, can have a significant contribution to shortwave radiation absorption in the atmosphere. The absorbing fraction of OA is referred to as brown carbon (BrC). This study introduces one of the first implementations of BrC into the Community Atmosphere Model version 5 (CAM5), using a parameterization for BrC absorptivity described in Saleh et al. (2014). Nine-year experiments are run (2003–2011) with prescribed emissions and sea surface temperatures to analyze the effect of BrC in the atmosphere. Model validation is conducted via model comparison to single-scatter albedo and aerosol optical depth from the Aerosol Robotic Network (AERONET). This comparison reveals a model underestimation of single scattering albedo (SSA) in biomass burning regions for both default and BrC model runs, while a comparison between AERONET and the model absorption Ångström exponent shows a marked improvement with BrC implementation. Global annual average radiative effects are calculated due to aerosol–radiation interaction (REari; 0.13±0.01 W m−2) and aerosol–cloud interaction (REaci; 0.01±0.04 W m−2). REari is similar to other studies' estimations of BrC direct radiative effect, while REaci indicates a global reduction in low clouds due to the BrC semi-direct effect. The mechanisms for these physical changes are investigated and found to correspond with changes in global circulation patterns. Comparisons of BrC implementation approaches find that this implementation predicts a lower BrC REari in the Arctic regions than previous studies with CAM5. Implementation of BrC bleaching effect shows a significant reduction in REari (0.06±0.008 W m−2). Also, variations in OA density can lead to differences in REari and REaci, indicating the importance of specifying this property when estimating the BrC radiative effects and when comparing similar studies.

scholarly journals The importance of the representation of air pollution emissions for the modeled distribution and radiative effects of black carbon in the Arctic

2019 ◽  
Vol 19 (17) ◽  
pp. 11159-11183 ◽  
Author(s):  
Jacob Schacht ◽  
Bernd Heinold ◽  
Johannes Quaas ◽  
John Backman ◽  
Ribu Cherian ◽  
...  
Keyword(s):  
Air Pollution ◽  
Black Carbon ◽  
Arctic Region ◽  
The Arctic ◽  
Radiative Effect ◽  
Radiative Effects ◽  
Near Surface ◽  
Pollution Emissions ◽  
Air Pollution Emissions ◽  
The Arctic Region

Abstract. Aerosol particles can contribute to the Arctic amplification (AA) by direct and indirect radiative effects. Specifically, black carbon (BC) in the atmosphere, and when deposited on snow and sea ice, has a positive warming effect on the top-of-atmosphere (TOA) radiation balance during the polar day. Current climate models, however, are still struggling to reproduce Arctic aerosol conditions. We present an evaluation study with the global aerosol-climate model ECHAM6.3-HAM2.3 to examine emission-related uncertainties in the BC distribution and the direct radiative effect of BC. The model results are comprehensively compared against the latest ground and airborne aerosol observations for the period 2005–2017, with a focus on BC. Four different setups of air pollution emissions are tested. The simulations in general match well with the observed amount and temporal variability in near-surface BC in the Arctic. Using actual daily instead of fixed biomass burning emissions is crucial for reproducing individual pollution events but has only a small influence on the seasonal cycle of BC. Compared with commonly used fixed anthropogenic emissions for the year 2000, an up-to-date inventory with transient air pollution emissions results in up to a 30 % higher annual BC burden locally. This causes a higher annual mean all-sky net direct radiative effect of BC of over 0.1 W m−2 at the top of the atmosphere over the Arctic region (60–90∘ N), being locally more than 0.2 W m−2 over the eastern Arctic Ocean. We estimate BC in the Arctic as leading to an annual net gain of 0.5 W m−2 averaged over the Arctic region but to a local gain of up to 0.8 W m−2 by the direct radiative effect of atmospheric BC plus the effect by the BC-in-snow albedo reduction. Long-range transport is identified as one of the main sources of uncertainties for ECHAM6.3-HAM2.3, leading to an overestimation of BC in atmospheric layers above 500 hPa, especially in summer. This is related to a misrepresentation in wet removal in one identified case at least, which was observed during the ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) summer aircraft campaign. Overall, the current model version has significantly improved since previous intercomparison studies and now performs better than the multi-model average in the Aerosol Comparisons between Observation and Models (AEROCOM) initiative in terms of the spatial and temporal distribution of Arctic BC.

scholarly journals Tagged tracer simulations of black carbon in the Arctic: Transport, source contributions, and budget

2017 ◽  
Author(s):  
Kohei Ikeda ◽  
Hiroshi Tanimoto ◽  
Takafumi Sugita ◽  
Hideharu Akiyoshi ◽  
Yugo Kanaya ◽  
...  
Keyword(s):  
East Asia ◽  
Black Carbon ◽  
Long Range ◽  
Biomass Burning ◽  
East Asian ◽  
The Arctic ◽  
Long Range Transport ◽  
Middle Troposphere ◽  
Source Contributions ◽  
Range Transport

Abstract. We implemented a tagged tracer method of black carbon (BC) into a global chemistry-transport model GEOS-Chem, examined the pathways and efficiency of long-range transport from a variety of anthropogenic and biomass burning emission sources to the Arctic, and quantified the source contributions of individual emissions. Firstly, we evaluated the simulated BC by comparing it with observations at the Arctic sites and found that the simulated seasonal variations were improved by implementing an aging parameterization and reducing the wet scavenging rate by ice clouds. For tagging BC, we added BC tracers distinguished by source types (anthropogenic and biomass burning) and regions; the global domain was divided into 16 and 27 regions for anthropogenic and biomass burning emissions, respectively. Our simulations showed that BC emitted from Europe and Russia was transported to the Arctic mainly in the lower troposphere during winter and spring. In particular, BC transported from Russia was widely spread over the Arctic in winter and spring, leading to a dominant contribution of 62 % to the Arctic BC near the surface as the annual mean. In contrast, BC emitted from East Asia was found to be transported in the middle troposphere into the Arctic mainly over the Okhotsk Sea and East Siberia during winter and spring. We identified an important window area, which allowed a strong incoming of East Asian BC to the Arctic (130°–180° E and 3–8 km altitude at 66° N). The model demonstrated that the contribution from East Asia to the Arctic had a maximum at about 5 km altitude due to uplifting during the long-range transport in early spring. The efficiency of BC transport from East Asia to the Arctic was smaller than that from other large source regions such as Europe, Russia and North America. However, the East Asian contribution was most important for BC in the middle troposphere (41 %) and BC burden over the Arctic (27 %) because of the large emissions from this region. These results suggested that the main sources of the Arctic BC differed with altitude. The contribution of all the anthropogenic sources to Arctic BC concentrations near the surface was dominant (90 %) on an annual basis. The contributions of biomass burning in boreal regions (Siberia, Alaska and Canada) to the annual total BC deposition onto the Arctic were estimated to be 12–15 %, which became the maximum during summer.

scholarly journals Arctic black carbon during PAMARCMiP 2018 and previous aircraft experiments in spring

2021 ◽  
Author(s):  
Sho Ohata ◽  
Makoto Koike ◽  
Atsushi Yoshida ◽  
Nobuhiro Moteki ◽  
Kouji Adachi ◽  
...  
Keyword(s):  
Numerical Model ◽  
Black Carbon ◽  
Biomass Burning ◽  
Base Station ◽  
Anthropogenic Sources ◽  
The Arctic ◽  
Core Diameter ◽  
Model Simulations ◽  
Anthropogenic Contributions ◽  
Mass Concentrations

Abstract. Vertical profiles of the mass concentration of black carbon (BC) were measured at altitudes up to 5 km during the PAMARCMiP aircraft-based field experiment conducted around the Northern Greenland Sea (Fram Strait) during March and April 2018, with operation base Station Nord (81.6° N, 16.7° W). Median BC mass concentrations in individual altitude ranges were 7–18 ng m–3 at standard temperature and pressure at altitudes below 4.5 km. These concentrations were systematically lower than previous observations in the Arctic in spring conducted by ARCTAS-A in 2008 and NETCARE in 2015 and similar to those observed during HIPPO3 in 2010. Column amounts of BC for altitudes below 5 km in the Arctic (> 66.5° N, COLBC), observed during the ARCTAS-A and NETCARE experiments were higher by factors of 4.2 and 2.7, respectively, than those of the PAMARCMiP experiment. These differences could not be explained solely by the different locations of the experiments. The year-to-year variation of COLBC values generally corresponded to that of biomass burning activities in northern high latitudes over western and eastern Eurasia. Furthermore, numerical model simulations estimated the year-to-year variation of contributions from anthropogenic sources to be smaller than 30–40 %. These results suggest that the year-to-year variation of biomass burning activities likely affected BC amounts in the Arctic troposphere in spring, at least in the years examined in this study. The year-to-year variations in BC mass concentrations were also observed at the surface at high Arctic sites Ny-Ålesund and Barrow, although their magnitudes were slightly lower than those in COLBC. Numerical model simulations in general successfully reproduced the observed COLBC values for PAMARCMiP and HIPPO3 (within a factor of 2), whereas they markedly underestimated the values for ARCTAS-A and NETCARE by factors of 3.7–5.8 and 3.3–5.0, respectively. Because anthropogenic contributions account for nearly all of the COLBC (82–98 %) in PAMARCMiP and HIPPO3, the good agreements between the observations and calculations for these two experiments suggest that anthropogenic contributions were generally well reproduced. However, the significant underestimations of COLBC for ARCTAS-A and NETCARE suggest that biomass burning contributions were underestimated. In this study, we also investigated plumes with enhanced BC mass concentrations, which were affected by biomass burning emissions, observed at 5 km altitude. Interestingly, the mass-averaged diameter of BC (core) and the shell-to-core diameter ratio of BC-containing particles in the plumes were generally not very different from those in other air sampled, which were considered to be mostly aged anthropogenic BC. These observations provide useful bases to evaluate numerical model simulations of the BC radiative effect in the Arctic region in spring.

scholarly journals Black carbon measurements in the boundary layer over western and northern Europe

2010 ◽  
Vol 10 (6) ◽  
pp. 13797-13853 ◽  
Author(s):  
G. R. McMeeking ◽  
T. Hamburger ◽  
D. Liu ◽  
M. Flynn ◽  
W. T. Morgan ◽  
...  
Keyword(s):  
Physical Properties ◽  
Black Carbon ◽  
Light Absorption ◽  
Urban Areas ◽  
Global Climate ◽  
Lower Troposphere ◽  
Climate Impacts ◽  
Air Mass ◽  
Lack Of Information ◽  
Mass Concentrations

Abstract. Europe is a densely populated region that is a significant global source of black carbon (BC) aerosol, but there is a lack of information regarding the physical properties and spatial/vertical distribution of BC in the region. We present the first aircraft observations of sub-micron BC aerosol concentrations and physical properties measured by a single particle soot photometer (SP2) in the lower troposphere over Europe. The observations spanned a region roughly bounded by 50° to 60° N and from 15° W to 30° E. The measurements, made between April and September 2008, showed that average BC mass concentrations ranged from about 300 ng m−3 near urban areas to approximately 50 ng m−3 in remote continental regions, lower than previous surface-based measurements. BC represented between 0.5 and 3% of the sub-micron aerosol mass. Black carbon mass size distributions were log-normally distributed and peaked at approximately 180 nm, but shifted to smaller diameters (~160 nm) near source regions. Black carbon was correlated with carbon monoxide (CO) but had different ratios to CO depending on location and air mass. Light absorption coefficients were measured by particle soot absorption photometers on two separate aircraft and showed similar geographic patterns to BC mass measured by the SP2, but differed by at least a factor of two compared to each other. We summarize the BC and light absorption measurements as a function of longitude and air mass age and also provide profiles of BC mass concentrations and size distribution statistics. Our results will help evaluate model-predicted regional BC concentrations and properties and determine regional and global climate impacts from BC due to atmospheric heating and surface dimming.

scholarly journals Black Carbon Seasonal and Diurnal Variation in surface snow in Svalbard and its Connections to Atmospheric Variables

2020 ◽  
Author(s):  
Michele Bertò ◽  
David Cappelletti ◽  
Elena Barbaro ◽  
Cristiano Varin ◽  
Jean-Charles Gallet ◽  
...  
Keyword(s):  
Black Carbon ◽  
The Arctic ◽  
Physico Chemical ◽  
Surface Snow ◽  
Seasonal And Diurnal Variation ◽  
Snow Precipitation ◽  
Common Association ◽  
Precipitation Events ◽  
Daily Time ◽  
Mass Concentrations

Abstract. Black Carbon (BC) is a major forcing agent in the Arctic but substantial uncertainty remains to quantify its climate effects due to the complexity of mechanisms involved. In this study, we provide unique information on processes driving the variability of BC mass concentration in surface snow in the Arctic. Two different snow-sampling strategies were adopted during spring 2014 and 2015, focusing on the refractory BC (rBC) mass Ny-Ålesund concentration daily/hourly variability on a seasonal/daily time scale (referred to as 80-days and 3-days experiments). Despite the low rBC mass concentrations (never exceeding 22 ng g−1), a daily variability of up to 4.5 ng g−1 was observed. Atmospheric, meteorological and snow-related physico-chemical parameters were considered in multiple statistical models to understand the factors behind the observed variation of rBC mass concentrations. Results indicate that the main drivers of the variation of rBC are the precipitations events, snow metamorphism (melting-refreezing cycles, surface hoar formation and sublimation) and the activation of local sources (wind resuspension) during the snow melting periods. The rBC in the snow seems de-coupled with the atmospheric BC load. Our results highlighted a common association of snow rBC with coarse mode particles number concentration and with snow precipitation events.

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