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人为气溶胶的最重要来源之一。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，对大气层产生总体冷却效应。它们还可以通过改变云的性质间接影响气候，例如，评估航运排放物对未来气候影响的两个关键挑战是（i）了解当今气溶胶系统的状况--作为进行气候预测的基线;（ii）量化排放的污染物数量。目前，对航运排放在北极和北大西洋大气中的影响几乎没有共识，主要是由于缺乏观测和模型技术不足。最近的模拟工作表明，北极气溶胶基线应考虑到各种不同的自然来源。很少有模型是足够全面的，虽然有些模型可以重现北极某些地区的气溶胶，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。不能反映气溶胶基线过程可能对未来气候预测的可靠性产生重大影响。航运业也在发生重大变化。2020年1月，国际海事组织（IMO）的一项新法规生效，该法规将船用燃料油中的硫含量降低了80%以上。除此之外，最近气候引起的北极海冰变化正在开辟新的海道，使主要市场之间的海上通道变得更短。预计未来几年通过西北航道的航运将大幅增长。因此，有一个很短的机会来确定当前的大气条件，SEANA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--气溶胶粒子的来源，包括航运的贡献--并确定2020年后ANAA气溶胶对新燃料标准的响应。将在邻近数值预报方案的两个观测站进行扩展测量，以便使用受体模型方法对颗粒源进行分配。此外，SEANA还将参加到NWP西侧的韩国巡航，以及到东部的NERC巡航，在两个截然不同的北极环境中测量自然和人为颗粒和气溶胶过程。这些新的观测结果将与最近的/在合作伙伴ANAA站进行持续测量，以生成ANAA气溶胶基线基准数据集，以约束英国领先的全球气溶胶过程模型，确保模型忠实地再现了ANAA中的基线气溶胶。然后，我们将利用2020年向低硫燃料过渡期间的观察结果，测试模型对航运硫排放大幅减少的反应。修订后的模型可以重现当前的“基线”，并准确预测ANAA中排放变化的响应，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将大大增强英国在捕获基线ANAA气溶胶和应对排放法规方面的国家能力，其结果将为高纬度地区的航运政策提供信息。

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.