The Airborne Arctic Stratospheric Expedition II (AASE II) which was based in Bangor, Maine between October 1991 and March 1992, with ER-2 flights from Ames Research Center, Fairbanks (Alaska), and Bangor; and DC-8 flights from Ames, Bangor, Anchorage (Alaska), Stavanger (Norway), and Tahiti, was a follow-up to an earlier AASE campaign in 1989. The dataset consists of measurements collected onboard the NASA ER-2 and DC-8 aircraft (for example, ClO, BrO, HCl, O3, NOx, N2O, HNO3, whole air samples and aerosol measurements). In addition, there are ozonesonde soundings from six Canadian stations, global grid point values of Nimbus 7 TOMS ozone, and selected radiosonde soundings from stations in the region of the experiment. Theory teams provided calculations of potential vorticity, temperature, geopotential, horizontal winds, parcel back trajectories, and concentrations of short lived species along the aircraft flight tracks; and northern hemispheric analyses of potential vorticity, temperature, geopotential, horizontal winds, and radiative heating rates.