Pure rotational-Raman channels of the Esrange lidar for temperature and particle extinction measurements in the troposphere and lower stratosphere

摘要

The Department of Meteorology at Stockholm University operates theEsrange Rayleigh/Raman lidar at Esrange (68° N,21° E) near the Swedish city of Kiruna. This paperdescribes the design and first measurements of the new purerotational-Raman channel of the Esrange lidar. The Esrange lidaruses a pulsed Nd:YAG solid-state laser operating at 532 nmas light source with a repetition rate of 20 Hz and a pulseenergy of 350 mJ. The minimum vertical resolution is 150 m andthe integration time for one profile is 5000 shots. The newlyimplemented channel allows for measurements of atmospherictemperature at altitudes below 35 km and is currentlyoptimized for temperature measurements between 180 and200 K. This corresponds to conditions in the lower Arcticstratosphere during winter. In addition to the temperaturemeasurements, the aerosol extinction coefficient and the aerosolbackscatter coefficient at 532 nm can be measuredindependently. Our filter-based design minimizes the systematicerror in the obtained temperature profile to less than0.51 K. By combining rotational-Raman measurements(5–35 km height) and the integration technique(30–80 km height), the Esrange lidar is now capable ofmeasuring atmospheric temperature profiles from the uppertroposphere up to the mesosphere. With the improved setup, thesystem can be used to validate current lidar-based polarstratospheric cloud classification schemes. The new capability ofthe instrument measuring temperature and aerosol extinctionfurthermore enables studies of the thermal structure and variabilityof the upper troposphere/lower stratosphere. Although several lidarsare operated at polar latitudes, there are few instruments that arecapable of measuring temperature profiles in the troposphere,stratosphere, and mesosphere, as well as aerosols extinction in thetroposphere and lower stratosphere with daylight capability.