Improving our understanding of the atmospheric sulfur cycle and its impact on air pollution and climate

颗粒物(PM)是一项主要的空气质量挑战，据估计，仅在英国一年就有29000人当量死亡，而且由于对地球辐射预算的直接和间接影响，也代表着当前气候模型预测中的一个重大不确定性。气相二氧化硫(SO2)的氧化是PM产生的核心，因此硫循环在气候系统中起着关键作用。据了解，人为的硫排放目前抵消了温室气体产生的热量的很大一部分，但通过排放控制(例如，管制运输和逐步淘汰煤炭)正在迅速减少。随着这些人为排放的减少，硫磺的自然来源，特别是从世界海洋排放的生物衍生硫化物，其贡献将增加。然而，最近的研究表明，我们对硫磺循环的了解不完整，特别是在偏远环境中，这影响了我们预测未来气候和空气污染情景的能力。直到最近，一个主要的挑战是，可用于测量二氧化硫的仪器还不够灵敏，无法探测到偏远地区的低本底水平，这破坏了更好地了解这些环境中硫循环的工作。在过去的三年里，约克大学开发了一种新的仪器，用于高灵敏地检测痕量二氧化硫，为增加我们对这一关键大气气体的了解打开了令人兴奋的机会。该项目将使用新开发的仪器进行测量，以促进我们对自然硫循环的理解。将通过以下目标实现这一目标：--改装测量二氧化硫沉积通量的约克二氧化硫仪器--将该仪器部署为地面和英国联邦航空管理局研究飞机上若干实地项目的一部分--利用这些实地项目的数据，通过与模型预测的比较，挑战和改善我们对大气二氧化硫化学的理解这项工作将填补我们在理解大气化学方面的重要知识空白，从而直接提高我们制定有效环境政策的能力。

Particulate matter (PM) is a major air quality challenge, estimated to be responsible for >29,000 equivalent deaths a year in the UK alone, and also represents a major uncertainty in current climate model predictions due to both the direct and indirect effects on the earths radiative budget. The oxidation of gas phase sulfur dioxide (SO2) is central to the production of PM, and as such the sulfur cycle plays a key role in the climate system. It is understood that anthropogenic sulfur emissions currently offset a significant fraction of the heating from greenhouse gases, but are declining rapidly through emission controls (e.g., regulation of shipping and phasing out of coal). As these anthropogenic emissions decline natural sources of sulfur, in particular biologically derived sulfur compounds emitted from the world's oceans, will increase in their fractional contribution. However, recent work has shown that we have an incomplete understanding of the sulfur cycle, particularly in remote environments, impacting our ability to predict future climate and air pollution scenarios. Until recently, a major challenge has been that the instrumentation available to measure SO2 has not been sensitive enough to detect the low background levels in remote locations, undermining work to better understand the sulfur cycle in these environments. Over the last 3 years a new instrument has been developed at the University of York for the highly sensitive detection of trace levels of SO2, opening up exciting opportunities to increase our understanding of this key atmospheric gas.This project will use newly developed instrumentation to make measurements that will be used to advance our understanding of the natural sulfur cycle. This will be achieved through the following objectives:- Modify the York SO2 instrument for the measurement of SO2 deposition fluxes- Deploy the instrument as part of several field projects, both on the ground and aboard the UK FAAM research aircraft- Use the data from these field projects to challenge and improve our understanding of atmospheric SO2 chemistry through comparison with model predictionsThis work will address important knowledge gaps in our understanding of atmospheric chemistry and thus directly improve our ability to design effective environmental policies.