Novel High-resolution Trace Gas Retrievals from Aircraft in Support of Regional Air Quality Modelling

The aim of this fellowship is to provide novel and simultaneous measurements of pollutant trace gas concentrations at high spatial resolution from an airborne infrared spectrometer in support of regional air quality modeling. Poor air quality in urban areas and those downwind of urban plumes has been shown to be detrimental to human health, with reduced life expectancy due to both long-term exposure at background urban pollution levels and short-term exposure to dramatically elevated pollutant levels in acute episodes such as heat waves for example. Those with pre-existing respiratory or cardiovascular disease are most at risk of experiencing a reduced quality of life. The World Health Organisation has reported that airborne particulate matter (also known as aerosol), ozone and nitrogen dioxide gas are the strongest contributors to such health impacts. Such health impacts are further exacerbated by climate change - the Intergovernmental Panel on Climate Change (IPCC) suggests that tropospheric concentrations of ozone and nitrogen dioxide are expected to increase with rising temperature. This is highlighted by the well-documented heat wave event of Western Europe in August 2003, which saw more than 44000 excess deaths across Europe, many due to heat stress but many also due to acute respiratory problems linked to elevated concentrations of the trace gases discussed above. Despite this important aspect of public health, the atmospheric processes leading to the production of the key pollutants responsible for health impacts remains poorly understood. To develop a strategy for dealing with the problem of poor air quality, such processes need to first be understood both at the city scale and within resulting plumes. Simultaneous measurement of many atmospheric pollutant concentrations at high spatial resolution is key to the accuracy of urban and regional air quality models, which use such concentrations as inputs. This need is currently not met by commonly used emissions inventories and low spatial resolution datasets, such as those currently offered by satellite remote sensing instruments. The ambition of this Fellowship is to meet this important measurement need by providing novel high resolution trace gas measurements for a range of pollutant trace gases pertinent to regional air quality modelling such as nitrogen dioxide, ozone and their reservoirs. Such data will be recorded simultaneously and for the first time from infrared spectra of the atmosphere recorded by the Airborne Research Interferometer Evaluation System (ARIES) instrument onboard the NERC Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 aircraft. To achieve this, the Fellow will use retrieval measurement techniques developed for ARIES as part of this fellowship. In partnership with the UK Met Office, a series of BAe-146 aircraft surveys (20 flying hours) will be conducted over and within the London urban pollution plume to measure pollutant concentrations downwind of the city. The new trace gas data will then be quantitatively compared to air quality model output generated as part of the ongoing Clean Air for London (ClearfLo) measurement and modelling study, which aims to characterise the processes leading to harmful air quality episodes. The results of the comparative study will be used to improve the ClearFlo plume model by understanding sources of bias in the plume model and its inputs. The aircraft surveys proposes as part of this Fellowship will be coordinated to coincide with periods of intensive ground measurement in London as part of ClearFlo in both Summer and Winter 2012. This new high-measurement capability will pave the way for a long-term dataset to support regional and global air quality modeling efforts, with future advances in satellite infrared remote sensing likely to provide synergistic large-scale but lower resolution trace gas concentration data for synchronized studies.