Lidar observations of polar stratospheric clouds and stratospheric temperature in winter 1995/96 over northern Norway

In winter 1995/96, extreme conditions were observed in the lower and middle stratosphere over most of the European Arctic. At the ALOMAR facility in Northern Norway, an ozone DIAL system observed PSCs on every measurement occasion in January and over a 10-days period in February 1996. On January 23, 1996, the PSC layer reached a maximum vertical extension, ranging from 19 to 27 km. In narrow layers, superimposed on the “background” PSC, the backscatter ratio R reached maximum values of 16 at 353 nm and about 9 on 308 nm. Morphology and colour index indicate that these narrow layers were type-II PSCs. Just above the PSC layer, temperatures below 190 K were recorded regularly. The temperatures at the edges of the “background” PSC allow this layer to be composed of STS.