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，它们改变污染物和温室气体臭氧（O3）的浓度，以及羟基自由基（OH），它负责去除许多其他大气污染物（例如CO， CH4）。亚硝酸气体（HONO）是一种特别活泼的氮，与NO和NO2有关，以前在雪上方的空气中观察到的水平高得惊人，这表明可能存在一个大的积雪源。该项目的目的是利用光学技术（LOPAP仪器）量化HONO排放，并使用同位素技术（15N/14N， 18O/16O和17O/16O比率）追踪极地地区活性氮的形成和损失过程。您将使用最先进的方法和仪器，在BAS剑桥和UEA Roland von Glasow空气-海冰室的实验室实验中测量冰雪上方活性氮的浓度、通量和同位素组成（HONO、NOx、HNO3、NO3-使用过滤器和环状脱光器分离），并可能在BAS在南极洲沿海运营的一个站点进行现场实验。您将使用数值空气-雪模型解释您的观测结果，以定量地了解雪上方大气的成分，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。您将成为BAS和东英吉利大学动态研究团队（AIC）的一员，该团队致力于极地地区广泛的环境主题。您将接受相关仪器和采样技术，建模和实地工作的全面培训。你将参加一所大气科学暑期学校，并获得支持，在同行评审的期刊和国际会议上发表研究成果。

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.