Improved understanding of Arctic atmospheric composition and climate through exploitation of satellite observations

Supervisors: Steve Arnold (SEE), Anna Jones (BAS), Richard Pope (NCEO/SEE)

The Arctic is undergoing rapid environmental change, and in recent decades has warmed at approximately twice the global mean rate. Radiative forcing (RF) from atmospheric CO2 increases and efficient high latitude climate feedbacks are responsible for the majority of Arctic warming. However, a significant part of the warming has been attributed to effects of changes in atmospheric concentrations of short-lived climate forcers (SLCFs), such as aerosol particles and tropospheric ozone. SLCFs affect Arctic temperatures via local RF produced by changes in their Arctic distributions, but also through RF imposed by changes in their abundances at lower latitudes, and subsequent changes in poleward heat transport. Arctic ozone and aerosol changes in response to natural feedbacks may also be important, for example as oceanic and terrestrial emission sources respond to rapid changes in temperature and ice & snow cover. Anticipated increases in shipping transiting the Arctic pose a further, direct, source of aerosols to the region. A major challenge in attributing changes in Arctic tropospheric composition and climate to remote and local influences from anthropogenic and natural emission sources is a severe paucity of in-situ observations of trace gas and aerosol, particularly over the long-term and through the vertical profile. This project will use satellite observations of tropospheric composition to constrain changes in these anthropogenic and natural influences on the Arctic over recent decades. The project will exploit multiple datasets from both nadir-viewing and limb sounders, and will focus on providing evaluation data for near-surface and upper troposphere composition in the high latitude region. Combining this data synthesis with aircraft & surface data and modeling, will allow new constraints on drivers of multi-annual observed rapid Arctic environmental change. Specific areas of investigation may include:

Development of a long-term synthesis of satellite data on Arctic tropospheric composition, through exploitation of multiple sensors over the past 25 years.
Evaluation of this long-term data synthesis with available in-situ datasets from aircraft.
Use of satellite data time-series in evaluation of long-term chemistry-climate model simulations of Arctic trace gas and aerosol.
Combining satellite data and chemistry-climate modeling to produce new estimates of ozone and aerosol radiative effects in the Arctic.
Using satellite data to improve understanding of natural emission influences on ozone and aerosol in the Arctic.
Using satellite data to improve understanding of long-range transport of trace gases and aerosol from mid-latitudes to the Arctic, and to evaluate these transport pathways in models.
Using satellite observations to detect temporal and spatial changes in high latitude local emissions of trace gases influencing the Arctic region.

The student will join active research teams in Leeds and BAS, focused on atmospheric chemistry modeling and analysis of satellite and aircraft data. The student will benefit from training in expertise in analysis of large geophysical datasets and remote sensing techniques, as well as numerical atmospheric chemistry-climate modelling. Extended collaborative visits for the student to the British Antarctic Survey will be expected (minimum 3 / yr, 1-2 weeks duration).