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Thule

General

The lidar in Thule was installed within a collaborative effort between the University of Rome, the Danish Meteorological Institute, and ENEA in November 1990. Thule is an US Air Force base located in North Western Greenland (76.5°N, 68.8°W). At the base several other instruments run by the Danish Meteorological Institute (DMI), NCAR, Stony Brook University at New York and INGV are operational.

The lidar was primarily dedicated to the measurement of upper tropospheric and stratospheric aerosols. In the following years, the capability to measure the temperature vertical profile in the stratosphere and mesosphere was added. During the winter campaign 2008-09 the lidar system was improved by the addition of two channels for the tropospheric aerosols. The system presently includes a linearly polarized Nd:YAG laser (532 nm, 10 Hz pulse repetition rate), a 80 cm diameter Cassegrain telescope, with two receiving channels at crossed polarizations; two 50 mm diameter refractive telescopes for the measurements of backscattered signals from the lower troposphere in two polarizations. The 80 cm telescope is equipped with a rotating chopper to prevent saturation of the detectors from the low-altitude signals. Measurement campaigns have been carried out since 1990; during several winters the lidar was operated jointly with DMI instruments (ozonesondes, backscattersondes, etc.) and the SUNY mm-wave spectrometer for the study of the straospheric structure and chemical composition. Based on the lidar measurements, studies have been carried out on the properties and the evolution of stratospheric aerosols, their interactions with stratospheric ozone, in particular after the 1991 eruption of volcano Pinatubo; on polar stratospheric clouds; on the polar vortex structure and evolution; on the thermal structure of the vortex; and on the occurrence of cirrus clouds at the tropopause.

Lidar Data Chart:

References

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