Spectroscope absorption measurements of the stratospheric trace gases hydrogen chloride (HCl) and nitric (HNO3) using a Fourier transform infrared spectrometer with the full moon as a light source at Arrival Heights

Spectroscope absorption measurements of the stratospheric trace gas hydrogen chloride (HCl) was measured using a Fourier transform infrared spectrometer with the full moon as a light source (sunlight reflected from the moons surface). Hydrogen chloride is extremely important as it is the principal reservoir species for stratospheric chlorine. The aim of this study was to better understand the annual cycle of chlorine and the winter processes leading to ozone depletion in the spring. Measurements are possible for around 5 days on either side of the moon, providing the sky is clear of cloud and the wind is not too strong.