Arctic haze is a seasonal phenomenon with high concentrations of accumulation-mode aerosols occurring in the Arctic in winter and early spring. Chemistry transport models and climate chemistry models struggle to reproduce this phenomenon, and this has recently prompted changes in aerosol removal schemes to remedy the modeling problems. In this paper, we show that shortcomings in current emission data sets are at least as important. We perform a 3 yr model simulation of black carbon (BC) with the Lagrangian particle dispersion model FLEXPART. The model is driven with a new emission data set ("ECLIPSE emissions") which includes emissions from gas flaring. While gas flaring is estimated to contribute less than 3% of global BC emissions in this data set, flaring dominates the estimated BC emissions in the Arctic (north of 66 N). Putting these emissions into our model, we find that flaring contributes 42% to the annual mean BC surface concentrations in the Arctic. In March, flaring even accounts for 52% of all Arctic BC near the surface. Most of the flaring BC remains close to the surface in the Arctic, so that the flaring contribution to BC in the middle and upper troposphere is small. Another important factor determining simulated BC concentrations is the seasonal variation of BC emissions from residential combustion (often also called domestic combustion, which is used synonymously in this paper). We have calculated daily residential combustion emissions using the heating degree day (HDD) concept based on ambient air temperature and compare results from model simulations using emissions with daily, monthly and annual time resolution. In January, the Arctic-mean surface concentrations of BC due to residential combustion emissions are 150% higher when using daily emissions than when using annually constant emissions. While there are concentration reductions in summer, they are smaller than the winter increases, leading to a systematic increase of annual mean Arctic BC surface concentrations due to residential combustion by 68% when using daily emissions. A large part (93%) of this systematic increase can be captured also when using monthly emissions; the increase is compensated by a decreased BC burden at lower latitudes. In a comparison with BC measurements at six Arctic stations, we find that using daily-varying residential combustion emissions and introducing gas flaring emissions leads to large improvements of the simulated Arctic BC, both in terms of mean concentration levels and simulated seasonality. Case studies based on BC and carbon monoxide (CO) measurements from the Zeppelin observatory appear to confirm flaring as an important BC source that can produce pollution plumes in the Arctic with a high BC /CO enhancement ratio, as expected for this source type. BC measurements taken during a research ship cruise in the White, Barents and Kara seas north of the region with strong flaring emissions reveal very high concentrations of the order of 200-400 ng m-3. The model underestimates these concentrations substantially, which indicates that the flaring emissions (and probably also other emissions in northern Siberia) are rather under- than overestimated in our emission data set. Our results suggest that it may not be "vertical transport that is too strong or scavenging rates that are too low" and "opposite biases in these processes" in the Arctic and elsewhere in current aerosol models, as suggested in a recent review article (Bond et al., Bounding the role of black carbon in the climate system: a scientific assessment, J. Geophys. Res., 2013), but missing emission sources and lacking time resolution of the emission data that are causing opposite model biases in simulated BC concentrations in the Arctic and in the mid-latitudes.
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机译：北极雾霾是一种季节性现象，冬季和初春时，北极地区会出现高浓度的累积模式气溶胶。化学迁移模型和气候化学模型难以重现此现象，最近这促使气溶胶去除方案发生变化，以弥补建模问题。在本文中，我们证明了当前排放数据集的缺陷至少同样重要。我们使用拉格朗日粒子分散模型FLEXPART对黑碳（BC）进行了3年的模型模拟。该模型由一个新的排放数据集（“ ECLIPSE排放量”）驱动，该数据集包括气体燃烧产生的排放量。虽然在此数据集中，天然气燃烧占全球BC排放量的不到3％，但在北极估计的BC排放量中，燃烧占主导地位（66 N以北）。将这些排放量放入我们的模型中，我们发现火炬燃烧对北极年平均BC表面浓度的贡献为42％。在三月份，喇叭口甚至占地表附近所有北极卑诗省地区的52％。在北极，大部分扩张的BC都保持靠近地表，因此在对流层中层和高层的扩张对BC的贡献很小。决定模拟的BC浓度的另一个重要因素是住宅燃烧（通常也称为家庭燃烧，在本文中是同义词）产生的BC排放的季节变化。我们已经根据环境空气温度使用了加热日（HDD）概念来计算了每日的住宅燃烧排放量，并将使用排放量的模型模拟结果与每日，每月和每年的时间分辨率进行了比较。 1月份，使用每日排放量时，由于住宅燃烧排放而导致的北极平均BC浓度比使用每年不变的排放量高150％。尽管夏季的浓度降低，但小于冬季的浓度降低，使用日排放量时，由于居民燃烧，导致北极BC年度平均表面浓度有系统地增加了68％。使用月度排放量时，也可以捕获到这一系统增加的很大一部分（93％）;在低纬度地区，BC负担的减少弥补了这一增加。通过与六个北极站的BC测量进行比较，我们发现使用日变化的居民燃烧排放并引入火炬气排放可以大大提高模拟北极BC的平均浓度水平和模拟季节性。根据齐柏林飞艇天文台的BC和一氧化碳（CO）测量结果进行的案例研究似乎证实，喇叭口是一种重要的BC源，可以在北极产生具有高BC / CO增强比的污染羽状体，正如这种源类型所期望的那样。在该区域以北的怀特，巴伦支和卡拉海的一艘研究船巡航期间进行的BC测量表明，该燃烧物具有强烈的燃烧散发，显示出200-400 ng m-3的非常高的浓度。该模型大大低估了这些浓度，这表明在我们的排放数据集中，火炬状的排放物（以及西伯利亚北部的其他排放物）可能被低估了，而不是被高估了。我们的结果表明，在北极和当前气溶胶模型的其他地方，可能不是“垂直运输太强或清除率太低”和“这些过程中的相反偏差”，正如最近的一篇评论文章（Bond等人，“界定黑碳在气候系统中的作用：科学评估，J。Geophys。Res。，2013），但缺少排放源，并且缺乏排放数据的时间分辨率，这在模拟的BC中造成了相反的模型偏差。集中在北极和中纬度地区。
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