SEANA -Shipping Emissions in the Arctic and North Atlantic atmosphere

航运是全球最大的货运方式。船舶消耗肮脏的燃料，使其成为海洋大气中最重要的人为气溶胶来源之一。航运产生的气溶胶可以通过吸收和散射辐射直接影响气候，从而对大气产生整体降温作用。它们还可以通过改变云的性质间接影响气候，例如反照率和寿命，从而进一步冷却大气。评估航运排放对未来气候的影响的两个关键挑战是：(1)了解当今气溶胶系统的状况--作为作出任何气候预测的基线；(2)量化污染物排放量。目前，关于北极和北大西洋大气层(ANAA)航运排放的影响几乎没有达成共识，这主要是因为缺乏观测和模型技能不足。最近的模拟工作表明，北极气溶胶基线应考虑一系列不同的自然来源。很少有模型足够全面，虽然一些模型可以在一些北极地区再现气溶胶，但有证据表明，模型可以通过不同的来源和过程产生类似的结果。如果不能反映气溶胶基线过程，可能会对未来气候预测的可靠性产生重大影响。航运业也正在经历重大变化。2020年1月，国际海事组织(IMO)的一项新规定生效，将船用燃料油中的硫含量降低了80%以上。在此基础上，最近气候导致的北冰洋海冰变化正在开辟新的海上通道，使关键市场之间的海上通道变得更短。预计在未来几年，通过西北航道(NWP)的运输量将大幅增长。因此，确定当前大气条件的机会很短，必须确定这些变化的影响。东盟将利用上述机会，在多个平台上进行多项大气测量，以了解目前的基线--气溶胶颗粒物的来源，包括航运的贡献--并确定2020年后国家航空航天局气溶胶对新燃料标准的反应。将在西北地区附近的两个站点进行扩展测量，以便利用受体模型方法分配颗粒物的来源。此外，西雅那航空公司还将参加前往北冰洋西侧的韩国航次和北冰洋东侧的北冰洋航次，以测量北极两个不同环境中的自然和人为颗粒物以及气溶胶过程。这些新的观测结果将与伙伴国家大气研究机构站最近/正在进行的测量相结合，以生成国家大气研究机构气溶胶基线基准数据集，以约束英国领先的全球气溶胶模型的过程，确保该模型忠实地再现国家大气研究机构的基准气溶胶。然后，我们将使用2020年向低硫燃料过渡期间进行的观察，测试模型对航运硫磺排放大幅减少的反应。修订后的模型可以再现当前的“基线”，并准确预测ANAA排放变化的反应，然后将用于预测在多种海冰和航运情景下，航运对空气质量、云和辐射强迫的未来影响。SEANA将大大增强英国捕获基准ANAA气溶胶的国家能力，并对排放法规做出回应，其结果将为高纬度地区的航运政策提供参考。

Shipping is the largest means of moving freight globally. Ships consume dirty fuels, making them one of the most important sources of anthropogenic aerosol in the marine atmosphere. Aerosols from shipping can affect the climate directly through absorption and scattering of radiation, with an overall cooling effect to the atmosphere. They can also indirectly influence the climate by changing cloud properties, e.g., albedo and lifetime, which further cools the atmosphere.Two key challenges for assessing future climate impact of shipping emission are (i) knowing the status of the present-day aerosol system - as a baseline from which any climate predictions are made and (ii) quantifying the amount of pollutants emitted. Currently little consensus exists on the impact of shipping emissions in the Arctic and North Atlantic Atmosphere (ANAA) primarily due to a lack of observations and insufficient model skills. Recent modelling work suggests that the Arctic aerosol baseline should account for a disparate range of natural sources. Few models are sufficiently comprehensive, and while some models can reproduce aerosol in some Arctic regions, there is evidence that models can produce similar results via different sources and processes. An inability to reflect the aerosol baseline processes can have significant impact on the reliability of future climate projections. Shipping is also undergoing significant changes. In January 2020, a new International Maritime Organisation (IMO) regulation comes into force, which reduces, by more than 80%, the sulphur content in maritime fuel oils. Superimposed on that, recent climate induced changes in Arctic sea ice are opening up new seaways enabling shorter sea passages between key markets. Significant growth in shipping via the North West Passage (NWP) is anticipated in the coming years. Thus, there is a short window of opportunity to define current atmospheric conditions, against which the impact of these changes must be determined.SEANA will take advantage of the above-mentioned opportunity to make multiple atmospheric measurements over multiple platforms to understand the present-day baselines - sources of aerosol particles including the contribution from shipping - and to determine the response of ANAA aerosol to new fuel standards after 2020. Extended measurements will be conducted at two stations adjacent to the NWP enabling the source of particles to be apportioned using receptor modelling approaches. In addition, SEANA will participate in a Korean cruise to the west side of the NWP, and a NERC cruise to the east, to measure both natural and anthropogenic particles and aerosol processes in two contrasting Arctic environments.These new observations will be integrated with recent / ongoing measurements at partner ANAA stations to generate a benchmark dataset on aerosol baseline in ANAA to constrain processes in the UK's leading global aerosol model, ensuring that the model is reproducing the baseline aerosol in the ANAA faithfully. We will then test the models' response to significant reductions in shipping sulphur emissions using observations taken during the transition to low-sulphur fuels in 2020. The revised model, which can reproduce current "baselines" and accurately predict the response of emission changes in the ANAA, will then be used to predict the future impact of shipping on air quality, clouds and radiative forcing under multiple sea-ice and shipping scenarios. SEANA will deliver a major enhancement of UK's national capacity in capturing baseline ANAA aerosol and responses to emission regulations, results of which will inform shipping policy at high-latitudes.