Investigation of the aerosol-cloud-radiation interactions over the Arctic during winter

据国际气候变化专门委员会称，北极将是地球上受温室气体增加影响最严重的地区。由于永久的冰雪覆盖，北极极易受到气候快速变化的影响。在这项研究中，研究了另一个有助于改变北极气候的重要因素，即人为气溶胶。尽管北极地处偏远，但它在冬天可能会受到严重污染。冬季的大气环流有利于北极上空大量硫酸盐、烟尘和有机化合物的保存和运输。这些气溶胶可以改变云的形成和演变，这在北极冬季是非常频繁的。反过来，云调节到达地表的地面辐射量，从而使地表变暖或变冷。本研究旨在改进气溶胶与云之间相互作用的模拟。本文还研究了硫酸盐气溶胶的一种新的间接效应，即脱水-温室反馈效应（DGF）。DGF可以在冬季为北极降温，从而部分抵消温室气体增加造成的变暖。

According to the International Panel on Climate Change, the Arctic will be the most affected region on Earth by the increase of greenhouse gases. Because of the permanent snow and ice cover, the Arctic is extremely vulnerable to rapid modification of its climate. In this research, another important factor contributing to modify the Arctic climate is investigated, anthropogenic aerosols. The Arctic can be very polluted during winter despite its remote location. The atmospheric circulation during winter favours the preservation and transport of large concentrations of sulphate, soot, and organic compounds over the Arctic. These aerosols can modify the formation and evolution of clouds, which are very frequent over the Arctic during winter. In turn, clouds regulate the amount of terrestrial radiation reaching the surface, thus contributing to either warm or cool the surface. This research aims at improving the simulation of the interactions between aerosols and clouds. A new indirect effect of sulphate aerosols, namely the dehydration-greenhouse feedback (DGF), is also investigated. The DGF could contribute to cool the Arctic during winter, thus partially counteracting the warming due to increasing greenhouse gases.