Coe Hugh, Wu Huihui, Marsden Nicholas, Biggart Michael, Bower Keith N, Choularton Tom, Flynn Michael, Gallagher Martin W, Hu Kezhen, Lloyd Gary, Nott Graeme J, Field Paul F, Murray Benjamin J
Department of Earth and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK.
National Centre for Atmospheric Sciences, University of Manchester, Manchester, M13 9PL, UK.
Faraday Discuss. 2025 Jun 16;258(0):147-170. doi: 10.1039/d5fd00005j.
Marine Arctic clouds greatly influence the radiative balance across the Arctic region and their effectiveness at scattering radiation changes considerably depending on cloud phase. Glaciation of these clouds relies on the presence of ice nucleating particles, which are often limited in number, so often clouds may be liquid even at temperatures well below 0 °C. As the Arctic region warms, cloud feedbacks may accelerate change or lessen absorbed solar radiation. Understanding aerosol-cloud interactions and the sources and pathways of aerosol particles across the Arctic region is central to improving our knowledge of these poorly understood processes. In this paper, aircraft observations of single particle chemical and physical properties are presented and the composition of cloud residuals in both warm and glaciated clouds are examined using a single-particle laser ablation aerosol particle mass spectrometer (LAAPToF). In cloud, the LAAPToF sampled behind a Counterflow Virtual Impactor (CVI) to detect cloud particle residuals, separated into liquid, mixed phase and ice clouds using observations of the fractional ice water content. Three different air mass regimes were sampled: northerly winds in both the marine boundary layer and the lower free troposphere; westerly winds from Canada in both the marine boundary layer and the free troposphere; and periods when the boundary layer winds were northerly but the air immediately above the boundary layer was from continental Canada. When the air in the boundary layer and free troposphere was from the north, most clouds were in the liquid phase, however, considerably more glaciation was observed when the air immediately above the boundary layer clouds was from Canada regardless of the flow direction in the boundary layer. Sea salt particles dominate the observed out of cloud aerosol particle population and liquid cloud particle residuals. However, in the detected mixed phase and ice cloud particle residuals dust and bioaerosol particles were substantial in number. Since these are known to be effective ice-nucleating particles, the observations suggest that long range transport of continental air and entrainment is an important pathway for the supply of aerosol to the remote Arctic boundary layer.
北极海洋云对整个北极地区的辐射平衡有很大影响，其散射辐射的效率会因云的相态而有很大变化。这些云的结冰依赖于冰核粒子的存在，而冰核粒子的数量往往有限，所以即使在远低于0°C的温度下，云通常也可能是液态的。随着北极地区变暖，云反馈可能会加速变化或减少吸收的太阳辐射。了解北极地区气溶胶与云的相互作用以及气溶胶粒子的来源和路径，对于增进我们对这些了解甚少的过程的认识至关重要。本文展示了对单个粒子化学和物理性质的飞机观测结果，并使用单粒子激光烧蚀气溶胶粒子质谱仪（LAAPToF）研究了暖云及结冰云中云残余物的组成。在云中，LAAPToF在逆流虚拟撞击器（CVI）之后进行采样以检测云粒子残余物，并利用冰水含量分数的观测结果将其分为液态云、混合相云和冰云。对三种不同的气团状态进行了采样：海洋边界层和低层自由对流层的北风；海洋边界层和自由对流层来自加拿大的西风；以及边界层风为北风但紧接边界层上方的空气来自加拿大大陆的时期。当边界层和自由对流层的空气来自北方时，大多数云处于液态，然而，无论边界层的气流方向如何，当紧接边界层云上方的空气来自加拿大时，观测到的结冰现象要多得多。海盐粒子在观测到的云外气溶胶粒子群体和液态云粒子残余物中占主导地位。然而，在检测到的混合相云和冰云粒子残余物中，尘埃和生物气溶胶粒子数量可观。由于已知这些是有效的冰核粒子，这些观测结果表明大陆空气的长距离输送和夹带是向偏远北极边界层供应气溶胶的重要途径。
