N₂O as an indicator of Arctic vortex dynamics: Correlations with O₃ over Thule, Greenland in February and March, 1992

We have recovered vertical profiles of stratospheric N₂O from spectra observed using a ground‐based mm‐wave spectrometer during the Arctic spring. The measurements were made from Thule, Greenland (76.3°N, 68.4°W) on nine occasions from late February to late March, 1992 as part of the Upper Atmosphere Research Satellite (UARS) Correlative Measurements Program and the European Arctic Stratospheric Ozone Experiment (EASOE). During late February Thule was under the inside edge of the Arctic vortex and mixing ratio profiles measured in that period are substantially reduced from typical high‐latitude summer values. By late March the polar vortex had moved well away from Thule and N₂O mixing ratios were greatly increased, coinciding with a basic change in circulation that brought in air from the Aleutian high. The motion of the vortex is also illustrated in the change in potential vorticity above Thule. A correlation with ozone balloonsonde data from Thule is made and compared to similar analyses of the Airborne Arctic Stratospheric Expedition (AASE) measurements. Within the sensitivity of our analysis, the correlation of N₂O and O₃ shows no evidence of ozone depletion within the vortex during this period; however, there is a distinct difference in the correlation inside and outside the vortex.