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

颗粒物（PM）是一个主要的空气质量挑战，估计仅在英国每年就造成超过29，000人死亡，并且由于对地球辐射预算的直接和间接影响，也是当前气候模型预测的主要不确定性。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，人为硫排放目前抵消了温室气体加热的很大一部分，但通过排放控制（例如，航运和逐步淘汰煤炭的监管）。随着这些人为排放量的减少，硫的天然来源，特别是从世界海洋排放的生物来源的硫化合物，将增加其份额。然而，最近的研究表明，我们对硫循环的理解不完全，特别是在偏远环境中，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，一个主要的挑战一直是可用于测量SO2的仪器不够灵敏，无法检测到偏远地区的低背景水平，从而破坏了更好地了解这些环境中硫循环的工作。在过去的3年里，约克大学开发了一种新的仪器，用于高灵敏度检测痕量二氧化硫，为增加我们对这种关键大气气体的了解提供了令人兴奋的机会。该项目将使用新开发的仪器进行测量，以促进我们对天然硫循环的了解。这将通过以下目标来实现：-修改约克SO2仪器，用于测量SO2沉积通量-将该仪器作为几个实地项目的一部分部署在地面和英国FAAM研究飞机上-通过与模型预测的比较，使用这些实地项目的数据来挑战和改善我们对大气SO2化学的理解这项工作将解决我们对大气化学理解的重要知识差距，从而直接提高我们设计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.