Abstract
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.
Highlights
Lidar measurements of tropospheric ozone have resulted in important contributions to atmospheric research
Vertical sounding, including lidar measurements of complementary quantities such as aerosols and water vapour (e.g. Trickl et al, 2014, 2015, 2020; Strawbridge et al, 2018; Fix et al, 2019), can yield key information for the understanding of the role of the underlying atmospheric processes, for a long time there was no significant growth in the number of tropospheric ozone lidar stations towards something like an international network
Lidar sounding of tropospheric ozone is a demanding technical task (Weitkamp et al, 2000) because of the considerable dynamical range of the backscatter signal covering up to about 8 decades, the presence of aerosols and clouds, interfering trace gases such as SO2 and NO2, and the solar background, all necessitating an elaborate optical and electronic design
Summary
Lidar measurements of tropospheric ozone have resulted in important contributions to atmospheric research. Lidar sounding of tropospheric ozone is a demanding technical task (Weitkamp et al, 2000) because of the considerable dynamical range of the backscatter signal covering up to about 8 decades, the presence of aerosols and clouds, interfering trace gases such as SO2 and NO2, and the solar background (stratospheric ozone measurements are normally made during night-time), all necessitating an elaborate optical and electronic design. In the mid-1990s a mobile ozone DIAL was built in cooperation with OHB System (Bremen, Germany; Brenner et al, 1997) This system, which was completed in spring 1996 and exhibited at the 1996 International Laser Radar Conference, could be operated in a vertical range between 0.2 and more than 4 km with a similar accuracy as our stationary system at low altitudes. Most of the approaches of the ozone DIAL systems have been successfully transferred to the other lidar systems of IMK-IFU
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