TRENDS AND VARIABILITY IN VERTICAL OZONE AND TEMPERATURE PROFILES MEASURED BY OZONESONDES AT LAUDER, NEW-ZEALAND - 1986-1996

A first analysis of trends in vertical ozone and temperature profiles from ozonesonde flights made at Lauder (45.045 degrees S, 169.684 degr ees E) between August 1986 and July 1996, is presented. To calculate t he trends and determine the magnitude of the forcing mechanisms underl ying the variability in ozone and temperature, a linear least squares regression model was applied to ozone mixing ratios, ozone number dens ities, and temperatures, interpolated onto 100 pressure levels from th e surface (969 hPa/370 m) to 12.1 hPa (similar to 30.1 km), similar to 300 geopotential meters apart. Ozone trends indicate wintertime upper tropospheric decreases of more than -30+/-24% per decade (2 sigma), p ost vortex breakup trends in a-narrow altitude region above the tropop ause of -20+/-20% per decade (2 sigma), and positive trends of up to 3 0+/-14% per decade (2 sigma) in the lower stratosphere during late win ter, spring, and early summer. The predominant temperature trend is +1 .5% per decade and greater above the similar to 50 hPa level during wi nter. Derived trends were sensitive to inclusion of tropopause height forcing which was found to influence ozone and temperature at a high l evel of statistical significance. Ozone at Lauder shows significant QB O dependence throughout the lower stratosphere during winter, spring, and early summer, but little or no dependence on the solar;cycle. Temp eratures, however, show little dependence on QBO but were influenced b y the solar cycle. The Mt. Pinatubo eruption had little influence on L auder ozone but significantly cooled the troposphere. The ENSO cycle i n ozone and temperature was weak except at the uppermost analysis leve ls.