Lidar observations of stratospheric aerosols have been performed at Ny-Aalesund (79 degrees N, 12 degrees East), Svalbard every winter since January 1994. We detected many PSC events in the stratosphere under low temperature condition, especially in 1994/95, 1995/96, 1996/97 winter campaigns. Meanwhile in the Antarctic, lidar observations were made from April, 1997 to January, 1998 at Dome Fuji (78 degrees South, 40 degrees East), and many PSCs were detected almost every day from the end of May to mid October. In the Arctic, PSC layers at the initial stage of appearance were composed mainly of solid particles in each winter season and the layers at sufficiently low temperatures were composed of spherical particles. In the Antarctic, PSCs similar to those over Ny- Aalesund were also detected frequently while the polar vortex was developing or the vortex was unstable. But after a remarkable decrease in the temperature by the invasion of blocking high into the polar vortex, PSCs detected were mainly composed of solid particles.
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