Measurements of stratospheric composition in the Canadian Arctic during spring 1999-2002 using a UV-visible spectrometer

In order to investigate the influence of chemical processes on Arctic ozone loss, we have deployed a UV-visible spectrometer at Environment Canada's Arctic Stratospheric Observatory (ASTRO), located at Eureka, NT. To date, three years (1999, 2000, and 2001) of zenith-sky observations have been obtained during the crucial winter/spring period when the perturbed conditions leading to chemical ozone depletion develop. Another Arctic campaign took place in winter/spring 2002 in Resolute Bay, NT. During these four Arctic field campaigns, the instrument was used to record zenith-sky spectra that have been analyzed for ozone and NO2 using differential optical absorption spectroscopy. The retrieved slant column densities have been converted into vertical column densities by means of air mass factors derived from a multiple scattering radiative transfer model. The total ozone columns compare favorably with concurrent ozone measurements, while the NO2 columns provide new information on the Arctic stratosphere. In this presentation, we describe the UV-visible spectrometer and present the four-year data set of springtime stratospheric measurements.