LAYERING IN STRATOSPHERIC PROFILES OF LONG-LIVED TRACE SPECIES - BALLOON-BORNE OBSERVATIONS AND MODELING

A series of balloon flights conducted in March 1993 from Aire-sur-Adou r, in southern France, aimed at making in situ measurements of a varie ty of trace gases in the polar vortex during a dynamically active peri od. Meteorological analyses indicate that the balloons were launched w hen the vortex edge was passing aloft. These mid latitude balloon flig hts revealed coincident layering in long-lived tropospheric source gas es such as nitrous oxide, methane and halocarbons as well. as in ozone and water vapor. At low altitudes, well-resolved laminations appeared clearly in all these gases. A layer of mid latitude air, enriched in trace gases, was detected at the highest sampled level, near 15 mbar, inducing a pronounced reversal in the profiles of tropospheric source gases. Using global meteorological analyses, trace constituent data de rived from the UARS observations and high-resolution advection models, fine-scale distributions of ozone, nitrous oxide, methane, and haloca rbons have been constructed. The calculations show qualitatively how s uch profile reversal arises near 15 mbar, when a filament of air enric hed in trace gases is drawn into the outer portion of the vortex. Very high resolution calculations furthermore provide reasonable quantitat ive agreement between predicted tracer mixing ratios and in situ ballo on-borne measurements.