Determination of Atmospheric Ozone Profiles at 68N and 79N with a Daylight Lidar Instrument

Abstract

The stratospheric ozone layer has recently received increased attention due to the globally observed decrease of the total ozone concentration¹ and the appearance of the so called ozone hole over Antarctica. Most of the information on global ozone is based on measurements of the ozone column density of the atmosphere. The vertical distribution of ozone can be measured by a light radar or lidar (Light Detection And Ranging). Laser-produced short light pulses are sent vertically into the atmosphere. The light is backscattered by the air molecules (Rayleigh scattering) and the signals of each pulse are recorded time-resolved, thereby providing the altitude resolution. For measurements of the ozone concentration the differential absorption principle is used (DIAL = Differential Absorption Lidar): light pulses at two wavelengths are emitted, which are chosen such, that one is partially absorbed by the ozone molecules and the other not. But the wavelength difference should be small enough, so that both waves experience the same backscattering process. Then many unknowns in the lidar equation, like atmospheric and instrumental parameters, can be eliminated. A recent description of the application of this principle to lidar ozone measurements is given by Steinbrecht et al.².