Parameterization of black carbon aging in the OsloCTM2 and implications for regional transport to the Arctic

Abstract. A critical parameter for the atmospheric lifetime of black carbon (BC) aerosols, and hence for the range over which the particles can be transported, is the aging time, i.e. the time before the aerosols become available for removal by wet deposition. This study compares two different parameterizations of BC aging in the chemistry transport model OsloCTM2: (i) A bulk parameterization (BULK) where aging is represented by a constant transfer to hydrophilic mode and (ii) a microphysical module (M7) where aging occurs through particle interaction and where the particle size distribution is accounted for. We investigate the effect of including microphysics on the distribution of BC globally and in the Arctic. We also focus on the impact on estimated contributions to Arctic BC from selected emission source regions. With more detailed microphysics (M7) there are regional and seasonal variations in aging. The aging is slower during high-latitude winter, when the production of sulfate is lower, than in lower latitudes and during summer. High-latitude concentrations of BC are significantly increased during winter compared to BULK. Furthermore, M7 improves the model performance at Arctic surface stations, especially the accumulation of BC during winter. A proper representation of vertical BC load is important because the climate effects of the aerosols depend on their altitude in the atmosphere. Comparisons with measured vertical profiles indicate that the model generally overestimates the BC load, particularly at higher altitudes, and this overestimation is exacerbated with M7 compared to BULK. Both parameterizations show that north of 65° N emissions in Europe contribute most to atmospheric BC concentration and to BC in snow and ice. M7 leads to a pronounced seasonal pattern in contributions and contributions from Europe and Russia increase strongly during winter relative to BULK. There is generally an increase in the amount of BC in snow and ice with M7 compared to BULK. However, in regions where the concentration of BC in snow is strongly underestimated with BULK compared to measurements, this increase with M7 is not sufficient to significantly improve the comparison.

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Parameterization of black carbon aging in the OsloCTM2 and implications for regional transport to the Arctic

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-32499-2011 ◽

2011 ◽

Vol 11 (12) ◽

pp. 32499-32534 ◽

Cited By ~ 5

Author(s):

M. T. Lund ◽

T. Berntsen

Keyword(s):

Black Carbon ◽

High Latitude ◽

Transport Model ◽

Seasonal Pattern ◽

Particle Interaction ◽

Model Performance ◽

High Arctic ◽

The Arctic ◽

The Impact ◽

Snow And Ice

Abstract. A critical parameter for the atmospheric lifetime of black carbon (BC) aerosols, and hence for the range over which the particles can be transported, is the aging time, i.e. the time before the aerosols become available for removal by wet deposition. This study compares two different parameterizations of BC aging in the chemistry transport model OsloCTM2: (i) a bulk parameterization (BULK) where aging is represented by a constant transfer to hydrophilic mode and (ii) a microphysical module (M7) where aging occurs through particle interaction and where the particle size distribution is accounted for. We investigate the effect of including microphysics on the distribution of BC globally and in the Arctic. We also focus on the impact on estimated contributions to Arctic BC from selected emission source regions. With more detailed microphysics (M7) there are regional and seasonal variations in aging. The aging is slower during high-latitude winter, when the production of sulfate is lower, than in lower latitudes and during summer. High-latitude concentrations of BC are significantly increased during winter compared to BULK. Furthermore, M7 improves the model performance at high Arctic surface stations, especially the accumulation of BC during winter. A proper representation of vertical BC load is important because the climate effects of the aerosols depend on their altitude in the atmosphere. Comparisons with measured vertical profiles indicate that the model generally overestimates the BC load, particularly at higher altitudes, and this overestimation is exacerbated with M7 compared to BULK. Both parameterizations show that north of 65° N emissions in Europe contribute most to atmospheric BC concentration and to BC in snow and ice. M7 leads to a pronounced seasonal pattern in contributions and contributions from Europe and Russia increase strongly during winter compared to BULK. There is generally a small increase in the amount of BC in snow and ice with M7 compared to BULK, but concentrations are still underestimated relative to measurements.

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

10.5194/acp-2020-1176 ◽

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.

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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

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-8637-2021 ◽

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.

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Source apportionment of circum-Arctic atmospheric black carbon from isotopes and modeling

Science Advances ◽

10.1126/sciadv.aau8052 ◽

2019 ◽

Vol 5 (2) ◽

pp. eaau8052 ◽

Cited By ~ 15

Author(s):

P. Winiger ◽

T. E. Barrett ◽

R. J. Sheesley ◽

L. Huang ◽

S. Sharma ◽

...

Keyword(s):

Black Carbon ◽

Biomass Burning ◽

Climate Warming ◽

Transport Model ◽

The Arctic ◽

Emission Inventories ◽

Source Contributions ◽

Model Predictions ◽

The Impact ◽

Good Agreement

Black carbon (BC) contributes to Arctic climate warming, yet source attributions are inaccurate due to lacking observational constraints and uncertainties in emission inventories. Year-round, isotope-constrained observations reveal strong seasonal variations in BC sources with a consistent and synchronous pattern at all Arctic sites. These sources were dominated by emissions from fossil fuel combustion in the winter and by biomass burning in the summer. The annual mean source of BC to the circum-Arctic was 39 ± 10% from biomass burning. Comparison of transport-model predictions with the observations showed good agreement for BC concentrations, with larger discrepancies for (fossil/biomass burning) sources. The accuracy of simulated BC concentration, but not of origin, points to misallocations of emissions in the emission inventories. The consistency in seasonal source contributions of BC throughout the Arctic provides strong justification for targeted emission reductions to limit the impact of BC on climate warming in the Arctic and beyond.

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Sensitivity of black carbon concentrations and climate impact to aging and scavenging

10.5194/acp-2016-782 ◽

2016 ◽

Author(s):

Marianne T. Lund ◽

Terje K. Berntsen ◽

Bjørn H. Samset

Keyword(s):

Nitric Acid ◽

Black Carbon ◽

Radiative Forcing ◽

Mitigation Strategies ◽

The Arctic ◽

Climate Mitigation ◽

Vertical Profiles ◽

The Impact ◽

Model Measurement ◽

Global Mean

Abstract. Despite recent improvements, significant uncertainties in global modeling of black carbon (BC) aerosols persist, posing important challenges for the design and evaluation of effective climate mitigation strategies targeted at BC emission reductions. Here we investigate the sensitivity of BC concentrations in the chemistry-transport model OsloCTM2 with the microphysical aerosol parameterization M7 (OsloCTM2-M7) to parameters controlling aerosol aging and scavenging. We focus on Arctic surface concentrations and remote region BC vertical profiles, and introduce a novel treatment of condensation of nitric acid on BC. The OsloCTM2-M7 underestimates annual averaged BC surface concentrations, with a mean normalized bias of −0.55. The seasonal cycle and magnitude of Arctic BC surface concentrations is improved compared to previous OsloCTM2 studies, but model-measurement discrepancies during spring remain. High-altitude BC over the Pacific is overestimated compared with measurements from the HIPPO campaigns. We find that a shorter global BC lifetime improves the agreement with HIPPO, in line with other recent studies. Several processes can achieve this, including allowing for convective scavenging of hydrophobic BC and reducing the amount of soluble material required for aging. Simultaneously, the concentrations in the Arctic are reduced, resulting in poorer agreement with measurements in part of the region. A first step towards inclusion of aging by nitrate in OsloCTM2-M7 is made by allowing for condensation of nitric acid on BC. This results in a faster aging and reduced lifetime, and in turn to a better agreement with the HIPPO measurements. On the other hand, model-measurement discrepancies in the Arctic are exacerbated. Work to further improve this parameterization is needed. The impact on global mean radiative forcing (RF) and surface temperature response (TS) in our experiments is estimated. Compared to the baseline, decreases in global mean direct RF on the order of 10–30 % of the total pre-industrial to present BC direct RF is estimated for the experiments that result in the largest changes in BC concentrations. We show that globally tuning parameters related to BC aging and scavenging can improve the representation of BC vertical profiles in the OsloCTM2-M7 compared with observations. Our results also show that such improvements can result from changes in several processes and often depend on assumptions about uncertain parameters such as the BC ice nucleating efficiency and the change in hygroscopicity with aging. It is also important to be aware of potential tradeoffs in model performance between different regions. Other important sources of uncertainty, particularly for Arctic BC, such as model resolution has not been investigated here. Our results underline the importance of more observations and experimental data to improve process understanding and thus further constrain models.

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Concentrations and source regions of light absorbing impurities in snow/ice in northern Pakistan and their impact on snow albedo

10.5194/acp-2017-667 ◽

2017 ◽

Author(s):

Chaman Gul ◽

Siva Praveen Puppala ◽

Shichang Kang ◽

Bhupesh Adhikary ◽

Yulan Zhang ◽

...

Keyword(s):

Radiative Forcing ◽

Transport Model ◽

Chemical Transport ◽

Small Contribution ◽

Northern Pakistan ◽

Chemical Transport Model ◽

Transport Modelling ◽

Snow Albedo ◽

Source Regions ◽

Snow And Ice

Abstract. Black carbon (BC), water-insoluble organic carbon (OC), and mineral dust are important particulate impurities in snow and ice, which significantly reduce albedo and accelerate melting. Surface snow and ice samples were collected from the Karakoram–Himalayan region of northern Pakistan during 2015 and 2016 in summer (six glaciers), autumn (two glaciers), and winter (six mountain valleys). The average BC concentration overall was 2130 ± 1560 ngg−1 in summer samples, 2883 ± 3439 ngg−1 in autumn samples, and 992 ± 883 ngg−1 in winter samples. The average water insoluble OC concentration overall was 1839 ± 1108 ngg−1 in summer samples, 1423 ± 208 ngg−1 in autumn samples, and 1342 ± 672 ngg−1 in winter samples. The overall concentration of BC, OC, and dust in aged snow samples collected during the summer campaign was higher than the concentration in ice samples. The values are relatively high compared to reports by others for the Himalayas and Tibetan Plateau. This is probably the result of taking more representative samples at lower elevation where deposition is higher and the effects of ageing and enrichment more marked. A reduction in snow albedo of 0.1–8.3 % for fresh snow and 0.9–32.5 % for aged snow was calculated for selected solar zenith angles during day time using the Snow, Ice, and Aerosol Radiation (SNICAR) model. Daily mean albedo was reduced by 0.07–12.0 %. The calculated radiative forcing ranged from 0.16 to 43.45 Wm−2 depending on snow type, solar zenith angle, and location. The potential source regions of the deposited pollutants were identified using spatial variance in wind vector maps, emission inventories coupled with backward air trajectories, and simple region tagged chemical transport modelling. Central, South, and West Asia were the major sources of pollutants during the sampling months, with only a small contribution from East Asia. Analysis based on the Weather Research and Forecasting (WRF-STEM) chemical transport model identified a significant contribution (more than 70 %) from South Asia at selected sites. Research into the presence and effect of pollutants in the glaciated areas of Pakistan is economically significant because the surface water resources in the country mainly depend on the rivers (the Indus and its tributaries) that flow from this glaciated area.

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Sources of Springtime Surface Black Carbon in the Arctic: An Adjoint Analysis

10.5194/acp-2016-1112 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ling Qi ◽

Qinbin Li ◽

Daven K. Henze ◽

Hsien-Liang Tseng ◽

Cenlin He

Keyword(s):

Natural Gas ◽

Black Carbon ◽

Biomass Burning ◽

Transport Model ◽

Lower Troposphere ◽

Anthropogenic Sources ◽

The Arctic ◽

Anthropogenic Source ◽

Gas Flaring ◽

Arctic Front

Abstract. We quantify source contributions to springtime (April 2008) surface black carbon (BC) in the Arctic by interpreting surface observations of BC at five receptor sites (Denali, Barrow, Alert, Zeppelin, and Summit) using a global chemical transport model (GEOS-Chem) and its adjoint. Contributions to BC at Barrow, Alert, and Zeppelin are dominated by Asian anthropogenic sources (40–43 %) before April 18 and by Siberian open biomass burning emissions (29–41 %) afterward. In contrast, Summit, a mostly free tropospheric site, has predominantly an Asian anthropogenic source contribution (24–68 %, with an average of 45 %). We compute the adjoint sensitivity of BC concentrations at the five sites during a pollution episode (April 20–25) to global emissions from March 1 to April 25. The associated contributions are the combined results of these sensitivities and BC emissions. Local and regional anthropogenic sources in Alaska are the largest anthropogenic sources of BC at Denali (63 %), and natural gas flaring emissions in the Western Extreme North of Russia (WENR) are the largest anthropogenic sources of BC at Zeppelin (26 %) and Alert (13 %). We find that long-range transport of emissions from Beijing-Tianjin-Hebei (also known as Jing-Jin-Ji), the biggest urbanized region in Northern China, contribute significantly (~ 10 %) to surface BC across the Arctic. On average it takes ~ 12 days for Asian anthropogenic emissions and Siberian biomass burning emissions to reach Arctic lower troposphere, supporting earlier studies. Natural gas flaring emissions from the WENR reach Zeppelin in about a week. We find that episodic, direct transport events dominate BC at Denali (87 %), a site outside the Arctic front, a strong transport barrier. The relative contribution of direct transport to surface BC within the Arctic front is much smaller (~ 50 % at Barrow and Zeppelin and ~ 10 % at Alert). The large contributions from Asian anthropogenic sources are predominately in the form of ‘chronic’ pollution (~ 40 % at Barrow and 65 % at Alert and 57 % at Zeppelin) on 1–2 month timescales. As such, it is likely that previous studies using 5- or 10-day trajectory analyses strongly underestimated the contribution from Asia to surface BC in the Arctic. Both finer temporal resolution of biomass burning emissions and accounting for the Wegener-Bergeron-Findeisen (WBF) process in wet scavenging improve the source attribution estimates.

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Climatological Biomass Burning CO – Where it comes from and where it goes.

10.5194/egusphere-egu2020-17829 ◽

2020 ◽

Author(s):

Nikos Daskalakis ◽

Maria Kanakidou ◽

Mihalis Vrekoussis ◽

Laura Gallardo

Keyword(s):

Biomass Burning ◽

Transport Model ◽

Source Region ◽

Atmospheric Composition ◽

Anthropogenic Sources ◽

3 Dimensional ◽

Source Regions ◽

The World ◽

Transport Patterns ◽

The Impact

Carbon Monoxide (CO) is an important atmospheric trace gas, and among the key O3 precursors in the troposphere, alongside NOx and VOCs. It is among the most important sinks of OH radical in the atmosphere, which controls lifetime of CH4 &#8212; a major greenhouse gas. Biomass burning sources contribute about 25% to the global emissions of CO, with the remaining CO being either emitted from anthropogenic sources, or being chemically formed in the atmosphere. Because of CO tropospheric lifetime is about two months; it can be transported in the atmosphere thus its sources have a hemispheric impact on atmospheric composition.The extent of the impact of biomass burning to remote areas of the world through long range transport is here investigated using the global 3-dimensional chemistry transport model TM4-ECPL. For this, tagged biomass burning CO tracers from the 13 different HTAP (land) source regions are used in the model in order to evaluate the contribution of each source region to the CO concentrations in the 170 HTAP receptor regions that originate from biomass burning. The global simulations cover the period 1994&#8212;2015 in order to derive climatological transport patterns for CO and assess the contribution of each of the source regions to each of the receptor regions in the global troposphere. The CO simulations are evaluated by comparison with satellite observations from MOPITT and ground based observations from WDCGG. We show the significant impact of biomass burning emissions to the most remote regions of the world.

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Atmospheric black carbon and sulfate concentrations in Northeast Greenland

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-9681-2015 ◽

2015 ◽

Vol 15 (16) ◽

pp. 9681-9692 ◽

Cited By ~ 24

Author(s):

A. Massling ◽

I. E. Nielsen ◽

D. Kristensen ◽

J. H. Christensen ◽

L. L. Sørensen ◽

...

Keyword(s):

Black Carbon ◽

Correlation Coefficient ◽

Seasonal Pattern ◽

Maximum Level ◽

High Arctic ◽

The Arctic ◽

Research Station ◽

Summer Period ◽

Transport Pathways ◽

Inorganic Matter

Abstract. Measurements of equivalent black carbon (EBC) in aerosols at the high Arctic field site Villum Research Station (VRS) at Station Nord in North Greenland showed a seasonal variation in EBC concentrations with a maximum in winter and spring at ground level. Average measured concentrations were about 0.067 ± 0.071 for the winter and 0.011 ± 0.009 for the summer period. These data were obtained using a multi-angle absorption photometer (MAAP). A similar seasonal pattern was found for sulfate concentrations with a maximum level during winter and spring analyzed by ion chromatography. Here, measured average concentrations were about 0.485 ± 0.397 for the winter and 0.112 ± 0.072 for the summer period. A correlation between EBC and sulfate concentrations was observed over the years 2011 to 2013 stating a correlation coefficient of R2 = 0.72. This finding gives the hint that most likely transport of primary emitted BC particles to the Arctic was accompanied by aging of the aerosols through condensational processes. BC and sulfate are known to have only partly similar sources with respect to their transport pathways when reaching the high Arctic. Aging processes may have led to the formation of secondary inorganic matter and further transport of BC particles as cloud processing and further washout of particles is less likely based on the typically observed transport patterns of air masses arriving at VRS. Additionally, concentrations of EC (elemental carbon) based on a thermo-optical method were determined and compared to EBC measurements. EBC measurements were generally higher, but a correlation between EC and EBC resulted in a correlation coefficient of R2 = 0.64. Model estimates of the climate forcing due to BC in the Arctic are based on contributions of long-range transported BC during spring and summer. The measured concentrations were here compared with model results obtained by the Danish Eulerian Hemispheric Model, DEHM. Good agreement between measured and modeled concentrations of both EBC/BC and sulfate was observed. Also, the correlation between BC and sulfate concentrations was confirmed based on the model results observed over the years 2011 to 2013 stating a correlation coefficient of R2 = 0.74. The dominant source is found to be combustion of fossil fuel with biomass burning as a minor, albeit significant source.

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Black carbon concentrations and mixing state in the Finnish Arctic

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-10057-2015 ◽

2015 ◽

Vol 15 (17) ◽

pp. 10057-10070 ◽

Cited By ~ 29

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.

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