IN-SITU OBSERVATIONS OF NOY, O-3, AND THE NOY O-3 RATIO IN THE LOWER STRATOSPHERE/

Extensive in situ measurements of reactive nitrogen (NOy) and ozone (O -3) were made in the lower stratosphere over a broad latitude range (6 0 degrees N-70 degrees S) during two different seasons (March and Octo ber) in 1994. Both NOy and O-3 mixing ratios show a strong latitude de pendence, with values increasing toward the poles. The NOy/O-3 ratio r eveals a high-gradient region near the tropics that is not well-repres ented in standard 2-D photochemical transport models. Improving the re presentation by changing the horizontal eddy-diffusion coefficients ne ar the tropics has important implications for the predicted impacts of aircraft emissions on stratospheric O-3.