Progress in atmospheric chemistry research is often linked to the availability of new techniques for measuring trace gas concentrations in the atmosphere. Field studies of the chemical composition of the troposphere and lower stratosphere demand highly specific and sensitive analytical instrumentation. For in-situ techniques, airborne operation is of great importance because the restrictions of measuring only within the planetary boundary layer can be overcome, the vertical distributions up to aircraft cruise altitude (as high as 24 km for some research aircraft) can be investigated, a large horizontal range can be covered in a short time period and because instrumentation can be deployed with relative ease in parts of the world where infrastructure is lacking, but which may be of special interest for atmospheric chemistry, e.g. in the tropics or in polar regions.
Our group is active in the development and field application of spectroscopic methods for trace gas detection and their use in investigating phenomena of current interest in atmospheric chemistry, including biospheric sources of greenhouse gases (CH4, N2O), biomass burning, regional oxidant formation, exchange processes between the troposphere and the lower stratosphere and other phenomena.
We have a close collaborative relationship with the Max Planck Institute for Chemistry in Mainz, Germany and a range of spectroscopic techniques are in use or under development at the laboratories there and at York. Foremost among these is absorption spectroscopy using tunable diode lasers (TDLAS) which we have applied to a wide variety of atmospheric measurements in ground based, ship-board and airborne campaigns. A new high precision, fast response diode laser spectrometer at York can be deployed aboard Canadian and US research aircraft operated by the Atmospheric Environment Service and the National Center for Atmospheric Research, respectively. A further instrument is used for eddy correlation studies of biospheric sources of N2O, CH4 and in airborne mode for dynamical studies of the lower stratosphere in the Arctic. At York, we are also carrying out laboratory spectroscopic studies using TDLAS to lay the groundwork for the use of the technique for a wider range of molecules in the future.
We are also engaged in development efforts leading to new spectroscopic techniques for atmospheric chemistry research including matrix isolation fourier transform infrared spectroscopy (MIFTIR) and cavity enhanced absorption spectroscopy (CEA). The former technique promises to be highly complementary to our TDLAS methods, being capable of measuring a wide variety of atmospheric species simultaneously at moderately high sensitivity, while we have are developing the second method, CEA, to demonstrate potentially ultra high sensitivity in a novel way.
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