Pollution transport efficiency toward the Arctic: Sensitivity to aerosol scavenging and source regions

Bourgeois, Quentin; Bey, I.

doi:10.1029/2010jd015096

Cited by 145 publications

(205 citation statements)

References 111 publications

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“…Over the glaciated areas of Greenland and the northern polar ice sheet, the reduction ranges between 10 and 20 %. However, although these changes are substantial, the known model biases in aerosol long-range transport to the Arctic, which have been found for ECHAM5-HAM1 by Bourgeois andBey (2011) andvon Hardenberg et al (2012), may still persist. A global doubling of emissions and fire intensity results in a southern hemispheric increase in regional deposition rates of 60-140 % (Fig.…”

Section: Total Deposition Ratesmentioning

confidence: 97%

Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

et al. 2015

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Abstract. Wildfires represent a major source for aerosols impacting atmospheric radiation, atmospheric chemistry and cloud micro-physical properties. Previous case studies indicated that the height of the aerosol-radiation interaction may crucially affect atmospheric radiation, but the sensitivity to emission heights has been examined with only a few models and is still uncertain. In this study we use the general circulation model ECHAM6 extended by the aerosol module HAM2 to investigate the impact of wildfire emission heights on atmospheric long-range transport, black carbon (BC) concentrations and atmospheric radiation. We simulate the wildfire aerosol release using either various versions of a semiempirical plume height parametrization or prescribed standard emission heights in ECHAM6-HAM2. Extreme scenarios of near-surface or free-tropospheric-only injections provide lower and upper constraints on the emission height climate impact. We find relative changes in mean global atmospheric BC burden of up to 7.9 ± 4.4 % caused by average changes in emission heights of 1.5-3.5 km. Regionally, changes in BC burden exceed 30-40 % in the major biomass burning regions. The model evaluation of aerosol optical thickness (AOT) against Moderate Resolution Imaging Spectroradiometer (MODIS), AErosol RObotic NETwork (AERONET) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations indicates that the implementation of a plume height parametrization slightly reduces the ECHAM6-HAM2 biases regionally, but on the global scale these improvements in model performance are small. For prescribed emission release at the surface, wildfire emissions entail a total sky top-of-atmosphere (TOA) radiative forcing (RF) of −0.16 ± 0.06 W m −2 . The application of a plume height parametrization which agrees reasonably well with observations introduces a slightly stronger negative TOA RF of −0.20 ± 0.07 W m −2 . The standard ECHAM6-HAM2 model in which 25 % of the wildfire emissions are injected into the free troposphere (FT) and 75 % into the planetary boundary layer (PBL), leads to a TOA RF of −0.24 ± 0.06 W m −2 . Overall, we conclude that simple plume height parametrizations provide sufficient representations of emission heights for global climate modeling. Significant improvements in aerosol wildfire modeling likely depend on better emission inventories and aerosol process modeling rather than on improved emission height parametrizations.

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Section: Total Deposition Ratesmentioning

confidence: 97%

Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

et al. 2015

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“…The observed distinct seasonal cycle with a minimum in summer and a maximum in late winter and early spring (Sharma et al, 2006) is closely related to transport from source regions outside the Arctic. Aerosol dry/wet removal at lower latitudes can strongly influence the distribution of aerosols at high latitudes (e.g., Kinne et al, 2006;Textor et al, 2007;Shindell et al, 2008;Bourgeois and Bey, 2011;Browse et al, 2012). Wet removal is considered to be the dominant process that determines the amount of aerosols being transported to remote regions and is also one of the most uncertain processes in global aerosol-climate models .…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of remote aerosol distributions to representation of cloud–aerosol interactions in a global climate model

et al. 2013

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Abstract. Many global aerosol and climate models, including the widely used Community Atmosphere Model version 5 (CAM5), have large biases in predicting aerosols in remote regions such as the upper troposphere and high latitudes. In this study, we conduct CAM5 sensitivity simulations to understand the role of key processes associated with aerosol transformation and wet removal affecting the vertical and horizontal long-range transport of aerosols to the remote regions. Improvements are made to processes that are currently not well represented in CAM5, which are guided by surface and aircraft measurements together with results from a multi-scale aerosol-climate model that explicitly represents convection and aerosol-cloud interactions at cloud-resolving scales. We pay particular attention to black carbon (BC) due to its importance in the Earth system and the availability of measurements.We introduce into CAM5 a new unified scheme for convective transport and aerosol wet removal with explicit aerosol activation above convective cloud base. This new implementation reduces the excessive BC aloft to better simulate observed BC profiles that show decreasing mixing ratios in the mid-to upper-troposphere. After implementing this new unified convective scheme, we examine wet removal of submicron aerosols that occurs primarily through cloud processes. The wet removal depends strongly on the subgrid-scale liquid cloud fraction and the rate of conversion of liquid water to precipitation. These processes lead to very strong wet removal of BC and other aerosols over mid-to high latitudes during winter months. With our improvements, the Arctic BC burden has a 10-fold (5-fold) increase in the winter (summer) months, resulting in a muchbetter simulation of the BC seasonal cycle as well. Arctic sulphate and other aerosol species also increase but to a lesser extent. An explicit treatment of BC aging with slower aging assumptions produces an additional 30-fold (5-fold) increase in the Arctic winter (summer) BC burden. This BC aging treatment, however, has minimal effect on other underpredicted species. Interestingly, our modifications to CAM5 that aim at improving prediction of high-latitude and uppertropospheric aerosols also produce much-better aerosol optical depth (AOD) over various other regions globally when compared to multi-year AERONET retrievals. The improved aerosol distributions have impacts on other aspects of CAM5, improving the simulation of global mean liquid water path and cloud forcing.

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“…However, Shwartz et al (2010) shows positive bias comparing global models with observation (Shwartz et al 2010, Sharma et al, 2013. These differences between model performances are 25 largely due to the high uncertainty in emissions and scavenging efficiency for calculating wet deposition (Bourgeois and Bey, 2011;Liu et al, 2015). Regional chemical transport models with a focus on the Arctic capture the BC concentration better over the Arctic.…”

mentioning

confidence: 99%

Source Sector and Region Contributions to Black Carbon and PM<sub>2.5</sub> in the Arctic

Sobhani¹,

Kulkarni²,

Carmichael³

2018

Preprint

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The impacts of BC and PM 2.5 emissions from different source sectors (e.g. transportation, power, 10 industry, residential, and biomass burning) and source regions (e.g. Europe, North America, China, Russia, Central Asia, South Asia, and the Middle East) to Arctic BC and PM 2.5 concentrations are investigated using a series of sensitivity runs with WRF-STEM modeling framework. The simulations are validated using 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 PM 2.5 with contributions of ~30%, ~25%, and 15 ~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; 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. 20Further sensitivity runs show that among various economic sectors of all geographic regions, European and Chinese residential sector contribute up to ~25% and ~14% to the Arctic average surface BC 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 Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-65 Manuscript under review for journal Atmos. Chem. Phys.

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Pollution transport efficiency toward the Arctic: Sensitivity to aerosol scavenging and source regions

Cited by 145 publications

References 111 publications

Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

Sensitivity of remote aerosol distributions to representation of cloud–aerosol interactions in a global climate model

Source Sector and Region Contributions to Black Carbon and PM<sub>2.5</sub> in the Arctic

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Pollution transport efficiency toward the Arctic: Sensitivity to aerosol scavenging and source regions

Cited by 145 publications

References 111 publications

Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

Sensitivity of remote aerosol distributions to representation of cloud–aerosol interactions in a global climate model

Source Sector and Region Contributions to Black Carbon and PM&lt;sub&gt;2.5&lt;/sub&gt; in the Arctic

Contact Info

Product

Resources

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Source Sector and Region Contributions to Black Carbon and PM<sub>2.5</sub> in the Arctic