STRATOSPHERIC METEOROLOGICAL CONDITIONS IN THE ARCTIC POLAR VORTEX, 1991 TO 1992

Stratospheric meteorological conditions during the Airborne Arctic Str atospheric Expedition II (AASE II) presented excellent observational o pportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 k) should have formed over small regions in ear ly December. The temperatures in the polar vortex warmed beyond NAT te mperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures.