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

冰岛的Fagradalsfjall喷发于2021年3月19日开始，直到4月27日，其特点是主要是二氧化硫在低空持续排出气体。4月27日，喷发的性质转变为连续的熔岩喷泉，然后在5月2日再次从连续喷泉转变为脉冲喷泉，高达300米，熔岩流量增加一倍。自4月27日以来，冰岛海岸外的火山柱发生了远程输送，卫星图像显示，火山喷发一直在影响北大西洋的云层。这次喷发提供了一个难得的机会，可以让飞机首次测量受火山活动干扰的云层特性。在过去的十年里，向我们大气的最低层排放二氧化硫等气体的火山喷发被认为是一个完美的天然实验室，可以研究排放如何影响云量和云的物理性质，包括组成云的微小液滴的大小。云层对气候有净降温作用，因为它们将一些进入太空的阳光反射回太空。众所周知，一旦气相物质转化为空气中的颗粒，二氧化硫(无论是人为的还是天然的)等气体的排放会导致云的性质发生变化，但尽管经过数十年的研究，云、颗粒和反射回太空的太阳光数量的相互作用的细节极其复杂，在气候模型中表示起来具有挑战性。该项目将提供对云特征的第一次测量，包括受火山排放影响地区的垂直变化。然后，这可以与没有受到火山排放影响的地区进行对比。当与卫星数据相结合时，我们的数据集将使我们能够对云和气溶胶粒子相互作用有一个新的理解，这反过来将有助于改进这些与气候相关的过程的模型表示。更好的模型将提供更准确的气候变化估计，这将有助于更好地准备和减轻气候变化的危害。

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.