The aim of this project is to install and operate high quality infrared and ultraviolet ground-based remote sensing instruments at a number of sites around 60°N in order to measure the concentrations of key stratospheric species. The data gathered will be coupled with meteorological data and interpreted using photochemical models to develop present understanding of stratospheric processes involved in ozone depletion, particularly during winter and spring.
The measurements and modelling work constituting this project are designed to:
- measure the concentrations of ozone and other stratospheric trace species at a number of sites in the latitude band spanning 52°N to 64°N in the period January 1994 to May 1995. Measurements in most instances will be in the form of a time series of vertical column amounts. For some species (03, NO2, HNO3 and HCl) it will be possible to derive altitude profiles;
- investigate the correlation between the measurements and the relative proximity of the polar vortex;
- determine the extent of ozone decreases due to chemically induced ozone loss during winter and investigate the transportation of ozone poor air from high latitudes during spring. This will rely on the use of trajectory modelling;
- quantitatively determine the chemical partitioning within the ClOy and NOy families in the stratosphere. Simultaneous measurements of some dynamical tracers (HF and N2O) will give an indication of the degrees of heterogeneous chemical processing.
Further tasks of the project are to extend the measurement capabilities of the instruments and to utilise these during SESAME Phase III:
- One FTIR and one UV-visible instrument will be developed so that the moon can be used as a source. This will provide night-time data and increase the frequency of the measurements.
- A UV-visible instrument will be developed with sufficient sensitivity and spectral resolution to allow measurements to OClO and BrO to be made.
- An FTIR will be used to make measurements from an aircraft during Phase III. This will increase the frequency of measurements and extend the geographical coverage.
- Improved data analysis algorithms will be implemented so that vertical profile information can be derived from high resolution infrared ground-based measurements and UV-visible spectra. The target molecules for these techniques will be HCl (from FTIR measurements) and O3 (from UV-visible measurements).
- A photochemical trajectory model will be used to predict vertical distribution of key trace species.
Funding SchemeCSC - Cost-sharing contracts
OX11 0QX Didcot,harwell,chilton
SY23 3BZ Aberystwyth
CB2 1EW Cambridge