QUASI-DECADAL VARIABILITY OF THE STRATOSPHERE - INFLUENCE OF LONG-TERM SOLAR ULTRAVIOLET VARIATIONS

A multiple regression statistical model is applied to investigate the existence of upper-stratospheric ozone, temperature, and zonal wind re sponses to long-term (solar cycle) changes in solar ultraviolet radiat ion using 11.5 years of reprocessed Nimbus-7 Solar Backscattered Ultra violet (SBUV) data and 12.4 years of National Meteorological Center (N MC) data. A positive solar cycle variation of independently measured o zone and temperature occurs with maximum amplitude near the low-latitu de stratopause. The seasonal solar regression coefficients near 1 mb f or both ozone and temperature occur at low latitudes supporting a role for photochemical and radiative forcing in their origin. Zonal wind p erturbations that correlate with long-term solar ultraviolet variation s are a strong function of season and pressure level. Above approximat ely 2 mbar, the largest solar-correlated zonal wind enhancements occur at middle winter latitudes near the time of winter solstice in both h emispheres. The Northern Hemisphere December enhancement at 1 mb was e specially large, 23 +/- 9 m s-1 from solar minimum to maximum during t he last solar cycle. The derived ozone, temperature, and zonal wind in creases with increasing solar ultraviolet flux near the stratopause ar e larger than predicted by models that consider primarily photochemica l and radiative processes. The higher ozone and temperature response a mplitudes at low latitudes may be due to modified ozone transport and adiabatic temperature changes induced by the dynamical response. If th e midlatitude winter solstice wind enhancements are solar induced, the ir high amplitudes require a positive feedback due to wave-mean flow i nteraction such that the planetary wave drag on the flow is reduced un der solar maximum conditions.