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

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.