ARCTIC TROPOSPHERIC AEROSOLS AND CLOUDS IN THE POLAR NIGHT SEASON OBSERVED BY A LIDAR AT EUREKA, CANADA

Vertical profiles of tropospheric aerosols and clouds were observed wi th a lidar at Eureka (80 degrees N, 86 degrees W) in the Canadian high Arctic. The observation periods were February, March and December 199 3, and January and February 1994. Observations were also performed fro m December 1994 to March 1995. Vertical distributions of aerosols and cloud particles are not easy to observe in the Arctic region especiall y in the polar night season. The lidar observations showed us the firs t overviews of Arctic tropospheric particle characteristics in mid-win ter. Ice crystals were often observed, which correlate very well with the relative humidity over ice that was observed by routine meteorolog ical observations by radiosonde. Particle layers in a very dry environ ment were sometimes observed.