ATMOS MEASUREMENTS OF H2O- DEHYDRATION AND DENITRIFICATION IN THE VORTEX(2CH(4) AND TOTAL REACTIVE NITROGEN IN THE NOVEMBER 1994 ANTARCTIC STRATOSPHERE )

Simultaneous stratospheric volume mixing ratios (VMRs) measured inside and outside the Antarctic vortex by the Atmospheric Trace Molecule Sp ectroscopy (ATMOS) instrument in November 1994 reveal previously unobs erved features in the distributions of total reactive nitrogen (NOy) a nd total hydrogen (H2O+2CH(4)). Maximum removal of NOy due to sediment ation of polar stratospheric clouds (PSCs) inside the vortex occurred at a potential temperature (Theta) of 500-525 K (similar to 20 km), wh ere values were 5 times smaller than measurements outside. Maximum los s of H2O+2CH(4) due to PSCs occurred in the vortex at 425-450 K, VMRs inside the vortex were similar to 70% of corresponding values out side . The Antarctic and April 1993 Arctic measurements by ATMOS show no si gnificant differences in H2O+2CH(4) VMRs outside the vortices in the t wo hemispheres. Elevated NOy VMRs were measured inside the vortex near 700 K. Recent model calculations indicate that this feature results f rom downward transport of elevated NOy produced in the thermosphere an d mesosphere.