MEASUREMENTS OF N2O BY THE UARS IMPROVED STRATOSPHERIC AND MESOSPHERIC SOUNDER DURING THE EARLY NORTHERN WINTER 1991 92/

Measurements of stratospheric nitrous oxide made by the Improved Strat ospheric and Mesospheric Sounder (ISAMS) during the period 28 October 1991 - 18 January 1992 are presented. The data are consistent with the dynamical fields at the time, and are in extremely good qualitative a greement with similar data from the Nimbus-7 SAMS and the Upper Atmosp here Research Satellite (UARS) Cryogenic Limb Array Etalon Spectromete r (CLAES) instruments, although in some regions the values are higher than have been obtained elsewhere. A major problem in the retrieval of the data has been contamination of the measured signal by aerosol emi tted during the Mount Pinatubo eruption of June 1991. Despite the unce rtainty in the values, the ISAMS N2O measurements provide a unique opp ortunity to study the synoptic evolution of a long-lived chemical trac er throughout the early winter, with near-continuous high-resolution m easurements. The zonally averaged data are shown, as well as the measu rements in the Northern Hemisphere on the 1150-K isentropic surface, w ith reference to temperature and wind fields from the same period deri ved also from ISAMS measurements. Finally, along-track cross sections are shown, which illustrate in greater detail the vertical and horizon tal structure of the northern winter vortex region.