Aircraft Measurements of Volcanic Aerosol-Cloud Interactions (Vol-ACI)

冰岛的Fagradalsfjall火山爆发于2021年3月19日开始，直到4月27日，其特征是低空持续脱气，主要是二氧化硫。4月27日，喷发的性质变成了连续的熔岩喷泉，然后在5月2日又从连续的变成了高达300米的脉冲喷泉，熔岩的排放率增加了一倍。自4月27日以来，冰岛海岸的火山羽流发生了长距离传输，卫星图像显示，火山爆发一直影响着北大西洋的云层。火山爆发提供了一个难得的机会，使有史以来第一次飞机测量云的性质扰动火山活动。在过去的十年中，火山喷发将二氧化硫等气体排放到我们大气层的最低层，被认为是研究排放如何影响云量和云的物理特性的完美自然实验室，其中包括组成云的微小液滴的大小。云对气候有净冷却作用，因为它们将一些入射的阳光反射回太空。众所周知，二氧化硫等气体的排放（无论是人为的还是自然的）一旦气相物质转化为空气中的颗粒，就会导致云的特性发生变化，但是云，颗粒和反射回太空的阳光量的相互作用的细节非常复杂，尽管经过数十年的研究努力，但在气候模型中表示具有挑战性。该项目将提供对云特征的首次测量，包括受火山排放影响地区的垂直变化。这可以与没有受到火山排放影响的地区形成对比。当与卫星数据相结合时，我们的数据集将使人们对云和气溶胶粒子的相互作用有一个新的理解，这反过来将有助于改善这些气候相关过程的模型表示。更好的模型将提供更准确的气候变化估计，这将有助于更好地防范和减轻气候变化危害。

The Fagradalsfjall eruption in Iceland began on 19th March 2021 and until the 27th of April was characterised by low-altitude continuous degassing of mainly sulfur dioxide. On 27th April, the nature of the eruption changed to continuous lava fountaining, then changed again on 2nd May from continuous to pulsed fountains up to 300m high with a doubled lava discharge rate. Since 27th April, long-range transport of the volcanic plume off the coast of Iceland has occurred and satellite imagery shows that the eruption has been influencing clouds in the North Atlantic. The eruption presents a rare opportunity to make the first ever aircraft measurements of cloud properties perturbed by volcanic activity. Volcanic eruptions that emit gases such as sulfur dioxide into the lowermost part of our atmosphere have been recognised in the last decade as a perfect natural lab to study how emissions affect cloud amount and the physical properties of clouds, which includes the size of the tiny droplets that make up clouds. Clouds have a net cooling effect on climate because they reflect some of the incoming sunlight back to space. It is also known that emissions of gases such as sulfur dioxide (be they man-made or natural) cause changes to cloud properties once the gas-phase species are converted to airborne particles, but the details of the interplay of clouds, particles and the amount of sunlight reflected back to space are extremely complex and challenging to represent in climate models despite decades of research efforts. This project would deliver the very first measurements of cloud characteristics including changes in the vertical in areas that have been affected by the volcanic emissions. This can then be contrasted to areas that have not been affected by volcanic emissions. When combined with satellite data, our dataset will enable a new understanding of cloud and aerosol particle interactions, which in turn will help to improve model representation of these climate-relevant processes. Better models will provide a more accurate estimate of climate change, which will help to better prepare and mitigate climate change hazards.