Quantifying and understanding dimethylsulfide variability and its influence on the climate system

英国气象局和NERC正在联合开发英国下一代地球系统模型。这个模型有一个很大的南大洋温度偏差，部分原因是云层允许太多的阳光到达海洋表面。这种温度偏差损害了未来气候预测的可靠性。云滴在大气中的微粒上形成。这些颗粒来自自然和人为的混合来源。更多的云滴意味着更亮（反射性更强）的云，穿过这些云的阳光就更少。当前云的亮度反映了自然“背景”粒子的产生，以及在南大洋上空运输的人为产生（人为）粒子的数量。这种自然/人为颗粒比例对于了解系统如何应对人为颗粒排放的增加/减少至关重要，因为“清洁”大气上的变化比已经“肮脏”的大气变化的影响要大得多。该研究旨在(1)确定该地区主要生物颗粒源二甲硫化物可能的背景排放水平和范围，(2)在气象局模型中实施这些排放的变化，(3)探索这对模型的南大洋和气候变化的影响。

The Met Office and NERC are jointly developing the UK's next generation Earth System Model. This model has a large Southern Ocean temperature bias arising in part from clouds allowing too much sunlight to reach the ocean's surface. This temperature bias compromises the reliability of future climate projections. Cloud droplets form on particles in the atmosphere. These particles come from a mixture of natural and human sources. More cloud droplets mean brighter (more reflective) clouds, and less sunlight passing through those clouds. Present-day cloud brightness reflects the natural 'background' particle production, and the number of human-produced (anthropogenic) particles that are transported over the Southern Ocean. This natural/anthropogenic particle ratio is critical to understand how the system will respond to increases/decreases in anthropogenic particle emissions, because changes on top of a 'clean' atmosphere have a much bigger impact than changes in an already 'dirty' atmosphere. This studentship aims to (1) determine the level and range of possible background emissions of the primary biological particle source in the region, dimethylsulphide, (2) implement changes to these emissions in the Met Office model, and (3) explore the implications of this for the model's Southern Ocean, and climate change.