Tropospheric Gases and Aerosols in Northeast Greenland

Heidam, Niels Z.; Wåhlin, Peter; Christensen, J. H.

doi:10.1175/1520-0469(1999)056<0261:tgaain>2.0.co;2

Cited by 61 publications

(80 citation statements)

References 16 publications

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“…The dominating southwesterly winds are caused by the katabatic flow from the ice cap. In order to minimize the effect of local pollution, the sampling site is placed southeast of the main complex (Heidam et al, 1999(Heidam et al, , 2004Nguyen et al, 2013). VRS is located west of the ice stream that floats out from the Arctic Ocean and thus there is both seasonal and multi-year ice right at the doorstep of the station.…”

Section: Measurement Sites and Instrumentationmentioning

confidence: 99%

Pan-Arctic aerosol number size distributions: seasonality and transport patterns

et al. 2017

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Abstract. The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station -Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed.A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intraand an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to ∼ 40 % from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites.The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulationmode particles (N acc ) at all five sites -often above 150 cm −3 .

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Section: Measurement Sites and Instrumentationmentioning

confidence: 99%

Pan-Arctic aerosol number size distributions: seasonality and transport patterns

et al. 2017

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“…Figure 4 shows the seasonal cycles of sulphate mixing ratio as simulated in the various simulations and measured at four Arctic sites: (a) Barrow, 1997(Quinn et al, 2007; (b) Alert, 1995Alert, -2002 (data available through the Canadian National Atmospheric Chemistry Database and Analysis System); (c) Zeppelin, 1995Zeppelin, -2005 (data available through the European Monitoring and Evaluation Programme (EMEP) database); and (d) Nord, Greenland, 1992-1995(Heidam et al, 1999. Overall, sulphate mass mixing ratios in the CAM5std are also strongly underpredicted, especially during the haze season.…”

Section: Improvements To Aerosols In High-mentioning

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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“…Several studies highlighted that the Arctic is significantly influenced by atmospheric pollution from midlatitudes -a phenomenon known as Arctic haze -during wintertime (Barrie et al, 1981;Heintzenberg et al, 1981;Shaw, 1982;Heidam et al, 1999Heidam et al, , 2004Bourgeois and Bey, 2011;Nguyen et al, 2013). Dastoor and Larocque (2004) used an online model to explain the observed seasonal variations in atmospheric mercury circulation and showed frequent episodes of mercury transport from midlatitudes sources to the Arctic in winter.…”

Section: Wintertime Advection Of Hg From Midlatitudesmentioning

confidence: 99%

Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models

et al. 2016

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Tropospheric Gases and Aerosols in Northeast Greenland

Cited by 61 publications

References 16 publications

Pan-Arctic aerosol number size distributions: seasonality and transport patterns

Pan-Arctic aerosol number size distributions: seasonality and transport patterns

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

Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models

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