Unravelling the mysteries of air quality above polar snow and ice using the isotopic fingerprints of reactive nitrogen

科学背景极地和高海拔地区的气候和环境对人为扰动特别敏感。了解背景大气中的自然过程对于评估人类对环境变化的贡献至关重要。例如，氮氧化物NO和NO2可以改变臭氧(一种污染物和温室气体)的浓度，而羟基自由基(OH)负责去除许多其他大气污染物(如CO、CH4)。亚硝酸气(HONO)是一种特别活跃的氮气，与NO和NO2有关，此前在雪上方的空气中观察到了令人惊讶的高水平，这表明可能存在大量积雪来源。这个项目的目的是用光学技术(LOPAP仪器)来量化HONO的排放，并使用同位素技术(15N/14N，18O/16O和17O/16O比率)来追踪极地地区活性氮的形成和损失过程。研究方法您将使用最先进的方法和仪器的组合来测量冰雪上活性氮的浓度、通量和同位素组成(HONO，NOx，HNO3，NO3-使用过滤器和环形剥离器分离)在实验室的BAS剑桥和UEA罗兰·冯·格拉斯托海-海冰室，并可能在南极沿海由BAS运营的一个空间站的野外。你将使用数值大气-雪模式来解释你的观察结果，以定量地了解雪上大气的组成，研究HONO和NOx之间的关系以及它们向HNO3和NO3-的转化，最终目标是改进全球化学-气候模型。培训你将成为BAS和UEA动态研究小组(AIC)的一员，这两个小组致力于极地地区的广泛环境主题。你将接受有关仪器和采样技术、建模和实地工作的全面培训。你将参加大气科学暑期班，并获得在同行评议的期刊和国际会议上发表成果的支持。

Scientific background Climate and environment in polar and high-altitude regions are particularly sensitive to anthropogenic perturbation. Understanding the natural processes in the background atmosphere is essential to assess the human contribution to environmental change. Examples are the nitrogen oxides NO and NO2, which alter concentrations of ozone (O3), a pollutant and greenhouse gas, and the hydroxyl radical (OH), which is responsible for the removal of many other atmospheric pollutants (e.g. CO, CH4). Nitrous acid gas (HONO) is a particularly reactive nitrogen species, related to NO and NO2, which has been observed previously at surprisingly high levels in air above snow, suggesting a large snowpack source may be present. The aim of this project is to quantify HONO emissions with an optical technique (LOPAP instrument) and to use isotopic techniques (15N/14N, 18O/16O and 17O/16O ratios) to trace reactive nitrogen formation and loss processes in polar regions.Research methodology You will use a combination of state-of-the art methods and instruments to measure the concentration, fluxes and isotopic composition of reactive nitrogen species (HONO, NOx, HNO3, NO3- separated using filters and annular denuders) above snow and ice in lab experiments at BAS Cambridge and the UEA Roland von Glasow Air-Sea-Ice Chamber, and potentially in the field at a station operated by BAS in coastal Antarctica. You will interpret your observations with a numerical air-snow model to quantitatively understand the composition of the atmosphere above snow, to study the relationship between HONO and NOx as well as their conversion to HNO3 and NO3-, with the ultimate goal to improve global chemistry-climate models.Training You will be part of dynamic research team (AIC) at BAS and UEA, which are working on a wide range of environmental topics in the polar regions. You will receive full training in the relevant instruments and sampling techniques, modelling and fieldwork. You will attend an atmospheric sciences summer school and receive support to publish results in peer-reviewed journals and at international conferences.