scholarly journals Black carbon concentrations and mixing state in the Finnish Arctic

2015 ◽  
Vol 15 (17) ◽  
pp. 10057-10070 ◽  
Author(s):  
T. Raatikainen ◽  
D. Brus ◽  
A.-P. Hyvärinen ◽  
J. Svensson ◽  
E. Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Particle Diameter ◽  
The Arctic ◽  
Mixing State ◽  
Core Mass ◽  
Source Regions ◽  
Mean Diameter ◽  
Absorbing Material ◽  
Optically Detected ◽  
Core Volume

Abstract. Atmospheric aerosol composition was measured using a Single Particle Soot Photometer (SP2) in the Finnish Arctic during winter 2011–2012. The Sammaltunturi measurement site at the Pallas GAW (Global Atmosphere Watch) station receives air masses from different source regions including the Arctic Ocean and continental Europe. The SP2 provides detailed information about mass distributions and mixing state of refractory black carbon (rBC). The measurements showed widely varying rBC mass concentrations (0–120 ng m−3), which were related to varying contributions of different source regions and aerosol removal processes. The rBC mass was log-normally distributed showing a relatively constant rBC core mass mean diameter with an average of 194 nm (75–655 nm sizing range). On average, the number fraction of particles containing rBC was 0.24 (integrated over 350–450 nm particle diameter range) and the average particle diameter to rBC core volume equivalent diameter ratio was 2.0 (averaged over particles with 150–200 nm rBC core volume equivalent diameters). These average numbers mean that the observed rBC core mass mean diameter is similar to those of aged particles, but the observed particles seem to have unusually high particle to rBC core diameter ratios. Comparison of the measured rBC mass concentration with that of the optically detected equivalent black carbon (eBC) using an Aethalometer and a MAAP showed that eBC was larger by a factor of five. The difference could not be fully explained without assuming that only a part of the optically detected light absorbing material is refractory and absorbs light at the wavelength used by the SP2. Finally, climate implications of five different black carbon mixing state representations were compared using the Mie approximation and simple direct radiative forcing efficiency calculations. These calculations showed that the observed mixing state means significantly lower warming effect or even a net cooling effect when compared with that of a homogenous aerosol containing the same amounts of black carbon and non-absorbing material.

scholarly journals Black carbon concentrations and mixing state in the Finnish Arctic

2015 ◽  
Vol 15 (11) ◽  
pp. 15621-15654 ◽  
Author(s):  
T. Raatikainen ◽  
D. Brus ◽  
A.-P. Hyvärinen ◽  
J. Svensson ◽  
E. Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
The Arctic ◽  
Core Size ◽  
Mixing State ◽  
Aerosol Composition ◽  
Total Size ◽  
Core Diameter ◽  
Source Regions ◽  
Absorbing Material

Abstract. Atmospheric aerosol composition was measured using a Single Particle Soot Photometer (SP2) in the Finnish Arctic during winter 2011–2012. The Sammaltunturi measurement site at the Pallas GAW (Global Atmosphere Watch) station receives air masses from different source regions including the Arctic Ocean and continental Europe. SP2 is a unique instrument that can give detailed information about mass distributions and mixing state of refractory black carbon (rBC). As expected, the measurements showed widely varying rBC mass concentrations (0–120 ng m−3), which were related to varying contributions of different source regions and aerosol removal processes. The log-normally distributed rBC core size was relatively constant with an average geometric mass mean diameter of 194 nm. On the average, the number fraction of particles containing rBC was 0.24 and the average rBC core size in these particles was half of the total size (coated to core diameter ratio was 2.0). These numbers mean that the core was larger and had a significantly thicker coating than in typical particles closer to their source regions. Comparison of the measured rBC mass concentration with that of the optically detected equivalent black carbon (eBC) showed a factor of five difference, which could not be fully explained without assuming that a part of the absorbing material is non-refractory. Finally, climate implications of five different rBC mixing state representations were quantified using the Mie approximation and simple direct radiative forcing efficiency calculations. These calculations showed that the observed mixing state (separate non-absorbing and coated rBC particles) means significantly lower warming effect or even a net cooling effect when compared with that of an homogenous aerosol containing the same amounts of rBC and non-absorbing material.

scholarly journals Size-resolved mixing state of black carbon in the Canadian high Arctic and implications for simulated direct radiative effect

2018 ◽  
Vol 18 (15) ◽  
pp. 11345-11361 ◽  
Author(s):  
John K. Kodros ◽  
Sarah J. Hanna ◽  
Allan K. Bertram ◽  
W. Richard Leaitch ◽  
Hannes Schulz ◽  
...  
Keyword(s):  
Black Carbon ◽  
State Constraints ◽  
Particle Diameter ◽  
High Arctic ◽  
The Arctic ◽  
Radiative Effect ◽  
Mixing State ◽  
Canadian High Arctic ◽  
Anthropogenic Aerosol ◽  
Total Particle

Abstract. Transport of anthropogenic aerosol into the Arctic in the spring months has the potential to affect regional climate; however, modeling estimates of the aerosol direct radiative effect (DRE) are sensitive to uncertainties in the mixing state of black carbon (BC). A common approach in previous modeling studies is to assume an entirely external mixture (all primarily scattering species are in separate particles from BC) or internal mixture (all primarily scattering species are mixed in the same particles as BC). To provide constraints on the size-resolved mixing state of BC, we use airborne single-particle soot photometer (SP2) and ultrahigh-sensitivity aerosol spectrometer (UHSAS) measurements from the Alfred Wegener Institute (AWI) Polar 6 flights from the NETCARE/PAMARCMIP2015 campaign to estimate coating thickness as a function of refractory BC (rBC) core diameter and the fraction of particles containing rBC in the springtime Canadian high Arctic. For rBC core diameters in the range of 140 to 220 nm, we find average coating thicknesses of approximately 45 to 40 nm, respectively, resulting in ratios of total particle diameter to rBC core diameters ranging from 1.6 to 1.4. For total particle diameters ranging from 175 to 730 nm, rBC-containing particle number fractions range from 16 % to 3 %, respectively. We combine the observed mixing-state constraints with simulated size-resolved aerosol mass and number distributions from GEOS-Chem–TOMAS to estimate the DRE with observed bounds on mixing state as opposed to assuming an entirely external or internal mixture. We find that the pan-Arctic average springtime DRE ranges from −1.65 to −1.34 W m−2 when assuming entirely externally or internally mixed BC. This range in DRE is reduced by over a factor of 2 (−1.59 to −1.45 W m−2) when using the observed mixing-state constraints. The difference in DRE between the two observed mixing-state constraints is due to an underestimation of BC mass fraction in the springtime Arctic in GEOS-Chem–TOMAS compared to Polar 6 observations. Measurements of mixing state provide important constraints for model estimates of DRE.

scholarly journals Effects of mixing state on optical and radiative properties of black carbon in the European Arctic

2018 ◽  
Author(s):  
Marco Zanatta ◽  
Paolo Laj ◽  
Martin Gysel ◽  
Urs Baltensperger ◽  
Stergios Vratolis ◽  
...  
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Particle Diameter ◽  
Arctic Region ◽  
Climate Impacts ◽  
Radiative Properties ◽  
The Arctic ◽  
Absorption Enhancement ◽  
Equivalent Diameter ◽  
Mixing State

Abstract. Atmospheric aging promotes internal mixing of black carbon (BC) leading to an enhancement of light absorption and radiative forcing. The relationship between BC mixing state and consequent absorption enhancement was never estimated for BC found in the Arctic region. In the present work, we aim to quantify the absorption enhancement and its impact on radiative forcing as a function of microphysical properties and mixing state of BC observed in-situ at the Zeppelin Arctic station (78° N) in the spring of 2012 during the CLIMSLIP (Climate impacts of short-lived pollutants in the Arctic) project. Single particle soot photometer (SP2) measurements showed a mean mass concentration of refractory black carbon (rBC) of 39 ng m−3, while the rBC mass size distribution was of log-normal shape peaking at an rBC mass equivalent diameter (DrBC) of around 240 nm. On average, the number fraction of particles containing a BC core with DrBC > 80 nm was less than 5 % in the size range (overall optical particle diameter) from 150–500 nm. The BC cores were internally mixed with other particulate matter. The median coating thickness of BC cores with 220 nm 

scholarly journals Long-term trends of black carbon and sulphate aerosol in the Arctic: changes in atmospheric transport and source region emissions

2010 ◽  
Vol 10 (5) ◽  
pp. 12133-12184 ◽  
Author(s):  
D. Hirdman ◽  
J. F. Burkhart ◽  
H. Sodemann ◽  
S. Eckhardt ◽  
A. Jefferson ◽  
...  
Keyword(s):  
Black Carbon ◽  
Atmospheric Circulation ◽  
Atmospheric Transport ◽  
Particle Dispersion ◽  
Downward Trend ◽  
The Arctic ◽  
Northern Eurasia ◽  
Source Regions ◽  
Long Term Trends

Abstract. As a part of the IPY project POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols and Transport) and building on previous work (Hirdman et al., 2010), this paper studies the long-term trends of both atmospheric transport as well as equivalent black carbon (EBC) and sulphate for the three Arctic stations Alert, Barrow and Zeppelin. We find a general downward trend in the measured EBC concentrations at all three stations, with a decrease of −2.1±0.4 ng m−3 yr−1 (for the years 1989–2008) and −1.4±0.8 ng m−3 yr−1 (2002–2009) at Alert and Zeppelin respectively. The decrease at Barrow is, however, not statistically significant. The measured sulphate concentrations show a decreasing trend at Alert and Zeppelin of −15±3 ng m−3 yr−1 (1985–2006) and −1.3±1.2 ng m−3 yr−1 (1990–2008) respectively, while the trend at Barrow is unclear. To reveal the influence of different source regions on these trends, we used a cluster analysis of the output of the Lagrangian particle dispersion model FLEXPART run backward in time from the measurement stations. We have investigated to what extent variations in the atmospheric circulation, expressed as variations in the frequencies of the transport from four source regions with different emission rates, can explain the long-term trends in EBC and sulphate measured at these stations. We find that the long-term trend in the atmospheric circulation can only explain a minor fraction of the overall downward trend seen in the measurements of EBC (0.3–7.2%) and sulphate (0.3–5.3%) at the Arctic stations. The changes in emissions are dominant in explaining the trends. We find that the highest EBC and sulphate concentrations are associated with transport from Northern Eurasia and decreasing emissions in this region drive the downward trends. Northern Eurasia (cluster: NE, WNE and ENE) is the dominant emission source at all Arctic stations for both EBC and sulphate during most seasons. In wintertime, there are indications that the EBC emissions from the eastern parts of Northern Eurasia (ENE cluster) have increased over the last decade.

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.

scholarly journals Responses of Arctic Black Carbon and Surface Temperature to Multi-Region Emission Reductions: an HTAP2 Ensemble Modeling Study

2020 ◽  
Author(s):  
Na Zhao ◽  
Xinyi Dong ◽  
Joshua S. Fu ◽  
Marianne Tronstad Lund ◽  
Kengo Sudo ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Black Carbon ◽  
Task Force ◽  
Regional Climate ◽  
The Arctic ◽  
Ensemble Modeling ◽  
Emission Reductions ◽  
Transport Pathways ◽  
Source Regions ◽  
The Impact

Abstract. Black carbon (BC) emissions play an important role in regional climate change of the Arctic. It is necessary to pay attention to the impact of long-range transport from regions outside the Arctic as BC emissions from local sources in the Arctic were relatively small. The Task Force Hemispheric Transport of Air Pollution Phase2 (HTAP2) set up a series of simulation scenarios to investigate the response of BC in a given region to different source regions. This study investigated the responses of Arctic BC concentrations and surface temperature to 20 % anthropogenic emission reductions from six regions in 2010 within the framework of HTAP2 based on ensemble modeling results. It was found that the emissions from East Asia (EAS) had most (18.1 %–51.4 %) significant impact on the Arctic while the monthly contributions from Europe, Middle East, North America, Russia Belarus Ukraine, and South Asia were 20.1 %–49.9 %, 0.02 %–0.9 %, 8.3 %–19.3 %, 5.4 %–18.1 %, and 3.1 %–7.7 %, respectively. The responses of the vertical profiles of the Arctic BC to the six regions were found to be different due to multiple transport pathways. The response of the Arctic BC to emission reductions of six source regions became less significant with the increase of the latitude. The benefit of BC emission reductions in terms of slowing down surface warming in the Arctic was evaluated by using Absolute Regional Temperature-change Potential (ARTP). Compared to the response of global temperature to BC emission reductions, the response of Arctic temperature was substantially more sensitive, highlighting the need for curbing global BC emissions.

scholarly journals Responses of Arctic black carbon and surface temperature to multi-region emission reductions: a Hemispheric Transport of Air Pollution Phase 2 (HTAP2) ensemble modeling study

2021 ◽  
Vol 21 (11) ◽  
pp. 8637-8654
Author(s):  
Na Zhao ◽  
Xinyi Dong ◽  
Kan Huang ◽  
Joshua S. Fu ◽  
Marianne Tronstad Lund ◽  
...  
Keyword(s):  
Air Pollution ◽  
Surface Temperature ◽  
Black Carbon ◽  
The Arctic ◽  
Ensemble Modeling ◽  
Phase 2 ◽  
Emission Reductions ◽  
Near Surface ◽  
Source Regions ◽  
The Impact

Abstract. Black carbon (BC) emissions play an important role in regional climate change in the Arctic. It is necessary to pay attention to the impact of long-range transport from regions outside the Arctic as BC emissions from local sources in the Arctic were relatively small. The task force Hemispheric Transport of Air Pollution Phase 2 (HTAP2) set up a series of simulation scenarios to investigate the response of BC in a given region to different source regions. This study investigated the responses of Arctic BC concentrations and surface temperature to 20 % anthropogenic emission reductions from six regions in 2010 within the framework of HTAP2 based on ensemble modeling results. Emission reductions from East Asia (EAS) had the most (monthly contributions: 0.2–1.5 ng m−3) significant impact on the Arctic near-surface BC concentrations, while the monthly contributions from Europe (EUR), Middle East (MDE), North America (NAM), Russia–Belarus–Ukraine (RBU), and South Asia (SAS) were 0.2–1.0, 0.001–0.01, 0.1–0.3, 0.1–0.7, and 0.0–0.2 ng m−3, respectively. The responses of the vertical profiles of the Arctic BC to the six regions were found to be different due to multiple transport pathways. Emission reductions from NAM, RBU, EUR, and EAS mainly influenced the BC concentrations in the low troposphere of the Arctic, while most of the BC in the upper troposphere of the Arctic derived from SAS. The response of the Arctic BC to emission reductions in six source regions became less significant with the increase in the latitude. The benefit of BC emission reductions in terms of slowing down surface warming in the Arctic was evaluated by using absolute regional temperature change potential (ARTP). Compared to the response of global temperature to BC emission reductions, the response of Arctic temperature was substantially more sensitive, highlighting the need for curbing global BC emissions.

Mixing State of Refractory Black Carbon of the North China Plain Regional Aerosol Combining a Single Particle Soot Photometer and a Volatility Tandem Differential Mobility Analyzer

2017 ◽  
Author(s):  
Yuxuan Zhang ◽  
Hang Su ◽  
Simonas Kecorius ◽  
Zhibin Wang ◽  
Min Hu ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
North China Plain ◽  
North China ◽  
Regional Scale ◽  
Particle Diameter ◽  
Differential Mobility Analyzer ◽  
Mixing State ◽  
Differential Mobility ◽  
Diurnal Cycles

Abstract. Black carbon (BC) aerosol particles play an important role in regulating earth's climate and their climate effects depend on their mixing state. During the CAREBeijing 2013 campaign, we measured the size-resolved mixing state of refractory BC particles in North China Plain and performed intercomparison between a single particle soot photometer (SP2) and a volatility tandem differential mobility analyzer (VTDMA). The intercomparison shows a good agreement between the optical particle diameter determined by SP2 and the mobility particle diameter determined by VTDMA for non-BC as well as for internally mixed refractory BC particles. The VTDMA shows a higher concentration of refractory particles than that of the SP2, which suggests the existence of a large fraction of low volatile non-BC aerosols. Following parameters were constrained by closure studies to improve the inversion of the mixing state of ambient BC (i.e., coating thickness (CT) and shell/core ratio (Dp / Dc)) by SP2: a) refractive indices (RI) of 1.42 and 1.67–0.56i for non-BC and rBC core components, respectively, b) refractory BC (rBC) core density of 1.2 g cm−3 for internally-mixed BC particles, and c) an effective density range of 0.25–0.45 g cm−3 for externally-mixed BC particles. Moreover, the upper limit of the measurable particle size of SP2 was extended by the leading-edge-only (LEO) fit from ~ 400 nm to ~ 550 nm as confirmed by the VTDMA measurement. Based on the improved inversion from SP2 measurement, we found that non-BC containing particles, internally-mixed BC and externally-mixed BC contribute 85–90 %, 5–7 % and 5–10 % of the total aerosol number in the size range of 200 nm to 350 nm. The number fraction of internally-mixed BC in total BC-containing aerosols (Fin) shows pronounced diurnal cycles with a peak around noon time and an apparent turnover rate up to 6–9 % h−1. Such diurnal cycles are similar to the finding of Cheng et al. (2012) suggesting the competing effect of emissions and aging processes. In this study, the observed internally-mixed BC particles in the polluted regional NCP (North China Plain) background site (Xianghe) suggest a rapid aging process of BC on the regional scale. During the intensive field study period, ~ 80 % of internally-mixed BC particles at 200–300 nm showed a Dp / Dc ratio of more than 2, accompanying with an average value of 2.3–2.8. Meanwhile, the CT of internally-mixed BC particles (200–350 nm) with rBC core size of 80–200 nm was in the range of 50–150 nm. Compared with previous measurements in developed countries, the observed BC particles on regional scale (i.e., internally-mixed BC particles) were more-aged, indicating stronger optical and climate effect of BC on the regional scale in northern China.

scholarly journals Size-selected black carbon mass distributions and mixing state in polluted and clean environments of northern India

2016 ◽  
Author(s):  
Tomi Raatikainen ◽  
David Brus ◽  
Rakesh K. Hooda ◽  
Antti-Pekka Hyvärinen ◽  
Eija Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Detailed Examination ◽  
Mixing State ◽  
Particle Properties ◽  
Mass Distributions ◽  
Northern India ◽  
Source Regions ◽  
Himalayan Foothills ◽  
Carbon Mass ◽  
Aerosol Mixing State

Abstract. We have measured black carbon properties by using a size-selected Single Particle Soot Photometer (SP2). The measurements were conducted in northern India at two sites: Gual Pahari is located at the Indo-Gangetic plains (IGP) and Mukteshwar at the Himalayan foothills. Northern India is known as one of the absorbing aerosol hot spots, but detailed information about absorbing aerosol mixing state is still largely missing. Previous black carbon mass concentration measurements are available for this region and these are consistent with our observations showing that refractory black carbon (rBC) concentrations are about ten times higher in Gual Pahari than those at Mukteshwar. Also the number fraction of absorbing particles is higher in Gual Pahari, but individual absorbing particles including their size distributions are fairly similar. These findings indicate that particles at both sites have similar local and regional emission sources, but aerosols are also transported from the main source regions (IGP) to the less polluted regions (Himalayan foothills). Detailed examination of the absorbing particle properties revealed that they are most likely fractal aggregates, but the exact structure remains unknown.

scholarly journals Size-selected black carbon mass distributions and mixing state in polluted and clean environments of northern India

2017 ◽  
Vol 17 (1) ◽  
pp. 371-383 ◽  
Author(s):  
Tomi Raatikainen ◽  
David Brus ◽  
Rakesh K. Hooda ◽  
Antti-Pekka Hyvärinen ◽  
Eija Asmi ◽  
...  
Keyword(s):  
Black Carbon ◽  
Detailed Examination ◽  
Mixing State ◽  
Gangetic Plain ◽  
Particle Properties ◽  
Mass Distributions ◽  
Northern India ◽  
Source Regions ◽  
Himalayan Foothills ◽  
Carbon Mass

Abstract. We have measured black carbon properties by using a size-selected single-particle soot photometer (SP2). The measurements were conducted in northern India at two sites: Gual Pahari is located at the Indo-Gangetic Plain (IGP) and Mukteshwar at the Himalayan foothills. Northern India is known as one of the absorbing aerosol hot spots, but detailed information about absorbing aerosol mixing state is still largely missing. Previous equivalent black carbon (eBC) mass concentration measurements are available for this region, and these are consistent with our observations showing that refractory black carbon (rBC) concentrations are about 10 times higher in Gual Pahari than those at Mukteshwar. Also, the number fraction of rBC-containing particles is higher in Gual Pahari, but individual rBC-containing particles and their size distributions are fairly similar. These findings indicate that particles at both sites have similar local and regional emission sources, but aerosols are also transported from the main source regions (IGP) to the less polluted regions (Himalayan foothills). Detailed examination of the rBC-containing particle properties revealed that they are most likely irregular particles such as fractal aggregates, but the exact structure remains unknown.

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