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.

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 Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

2017 ◽  
Author(s):  
Zilin Wang ◽  
Xin Huang ◽  
Aijun Ding
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Black Carbon ◽  
Rural Areas ◽  
Land Surface ◽  
Critical Role ◽  
Aerosol Layer ◽  
Near Surface ◽  
Haze Pollution ◽  
The Impact

Abstract. Black carbon (BC) has been identified to play a critical role in aerosol-planet boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been named as its dome effect. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, and also the underlying land surface, have not been quantitatively explored yet. Here, based on available in-situ measurements of meteorology and atmospheric aerosols together with the meteorology-chemistry online coupled model, WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC's dome effect and surface haze pollution, and discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on PBL is very sensitive to the altitude of aerosol layer. The upper level BC, especially those near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulence mixing. The dome effect of BC tends to be significantly intensified as BC aerosol mixed with scattering aerosols during winter haze events, resulting in a decrease of PBL height by more than 25 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such kind of effect to air quality in countryside. This study suggests that China's regional air pollution would greatly benefit from BC emission reductions, especially those from the elevated sources from the chimneys and also the domestic combustions in rural areas, through weakening the aerosol-boundary layer interactions that triggered by BC.

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 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 Dome effect of black carbon and its key influencing factors: a one-dimensional modelling study

2018 ◽  
Vol 18 (4) ◽  
pp. 2821-2834 ◽  
Author(s):  
Zilin Wang ◽  
Xin Huang ◽  
Aijun Ding
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Black Carbon ◽  
Rural Areas ◽  
Land Surface ◽  
Critical Role ◽  
Aerosol Layer ◽  
Near Surface ◽  
Haze Pollution ◽  
The Impact

Abstract. Black carbon (BC) has been identified to play a critical role in aerosol–planetary boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been referred to as the “dome effect”. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, as well as the underlying land surface, have not been quantitatively explored yet. Here, based on available in situ measurements of meteorology and atmospheric aerosols together with the meteorology–chemistry online coupled model WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC dome effect and surface haze pollution. Furthermore, we discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on the PBL is very sensitive to the altitude of aerosol layer. The upper-level BC, especially that near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulent mixing. The dome effect of BC tends to be significantly intensified as BC mixed with scattering aerosols during winter haze events, resulting in a decrease in PBL height by more than 15 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such an effect to air quality in countryside. This study indicates that China's regional air pollution would greatly benefit from BC emission reductions, especially those from elevated sources from chimneys and also domestic combustion in rural areas, through weakening the aerosol–boundary layer interactions that are triggered by BC.

The impact of shallow stratification on air-sea CO2 flux in the summer Arctic Ocean

2021 ◽  
Author(s):  
Yuanxu Dong ◽  
Dorothee Bakker ◽  
Thomas Bell ◽  
Peter Liss ◽  
Ian Brown ◽  
...  
Keyword(s):  
Surface Water ◽  
Wind Speed ◽  
Sea Ice ◽  
Surface Temperature ◽  
Arctic Ocean ◽  
The Arctic ◽  
Near Surface ◽  
Ice Melt ◽  
The Arctic Ocean ◽  
The Impact

<p>Air-sea carbon dioxide (CO<sub>2</sub>) flux is often indirectly estimated by the bulk method using the i<em>n-situ</em> air-sea difference in CO<sub>2</sub> fugacity and a wind speed dependent parameterisation of the gas transfer velocity (<em>K</em>). In the summer, sea-ice melt in the Arctic Ocean generates strong shallow stratification with significant gradients in temperature, salinity, dissolved inorganic carbon (DIC) and alkalinity (TA), and thus a near-surface CO<sub>2</sub> fugacity  (<em>f</em>CO<sub>2w</sub>) gradient. This gradient can cause an error in bulk air-sea CO<sub>2</sub> flux estimates when the <em>f</em>CO<sub>2w</sub> is measured by the ship’s underway system at ~5 m depth. Direct air-sea CO<sub>2</sub> flux measurement by eddy covariance (EC) is free from the impact of shallow stratification because the EC CO<sub>2</sub> flux does not rely on a <em>f</em>CO<sub>2w</sub> measurement. In this study, we use summertime EC flux measurements from the Arctic Ocean to back-calculate the sea surface <em>f</em>CO<sub>2w</sub> and temperature and compare them with the underway measurements. We show that the EC air-sea CO<sub>2</sub> flux agrees well with the bulk flux in areas less likely to be influenced by ice melt (salinity > 32). However, in regions with salinity less than 32, the underway <em>f</em>CO<sub>2w</sub> is higher than the EC estimate of surface <em>f</em>CO<sub>2w</sub> and thus the bulk estimate of ocean CO<sub>2</sub> uptake is underestimated. The <em>f</em>CO<sub>2w</sub> difference can be partly explained by the surface to sub-surface temperature difference. The EC estimate of surface temperature is lower than the sub-surface water temperature and this difference is wind speed-dependent. Upper-ocean salinity gradients from CTD profiles suggest likely difference in DIC and TA concentrations between the surface and sub-surface water. These DIC and TA gradients likely explain much of the near-surface <em>f</em>CO<sub>2w</sub> gradient. Accelerating summertime loss of sea ice results in additional meltwater, which enhances near-surface stratification and increases the uncertainty of bulk air-sea CO<sub>2</sub> flux estimates in polar regions.</p>

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

2012 ◽  
Vol 12 (15) ◽  
pp. 6999-7014 ◽  
Author(s):  
M. T. Lund ◽  
T. Berntsen
Keyword(s):  
Black Carbon ◽  
High Latitude ◽  
Transport Model ◽  
Seasonal Pattern ◽  
Particle Interaction ◽  
Model Performance ◽  
The Arctic ◽  
Source Regions ◽  
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 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.

scholarly journals Interannual Variability and Trends in Sea Surface Temperature, Lower and Middle Atmosphere Temperature at Different Latitudes for 1980–2019

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 454
Author(s):  
Andrew R. Jakovlev ◽  
Sergei P. Smyshlyaev ◽  
Vener Y. Galin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Lower Troposphere ◽  
Reanalysis Data ◽  
Sea Surface ◽  
The Arctic ◽  
The Impact

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.

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

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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