Three decades of tropospheric ozone lidar development at Garmisch-Partenkirchen, Germany

Abstract

Since 1988 two ozone lidar systems have been developed at IMK-IFU (Garmisch-Partenkirchen, Germany). A stationary system, operated at the institute, has yielded about 5000 vertical profiles of ozone from next to the ground to typically 3 km above the tropopause and has contributed data for a large number of scientific investigations. A mobile system was successfully operated in a number of field campaigns after its completion in 1996, before it was destroyed in major flooding in May 1999. Both systems combine high data quality with high vertical resolution dynamically varied between 50 m in the lower troposphere and 250–500 m below the tropopause (stationary system). The stationary system has been gradually upgraded over the years. The noise level of the raw data has reached about ±1×10-6 of the input range of the transient digitizers after minor smoothing. As a consequence, uncertainties in the ozone mixing ratios of 1.5 to 4 ppb have been achieved up to about 5 km. The performance in the upper troposphere, based on the wavelength pair 292–313 nm, varies between 5 and 15 ppb depending on the absorption of the 292 nm radiation by ozone and the solar background. In summer it is therefore planned to extend the measurement time from 41 s to a few minutes in order to improve the performance to a level that will allow us to trust automatic data evaluation. As a result of the time needed for manual refinement the number of measurements per year has been restricted to under 600. For longer time series automatic data acquisition has been used.