Stratospheric effects of 27-day solar ultraviolet variations: The column ozone response and comparisons of solar cycles 21 and 22

Abstract

Two unresolved observational issues concerning the response of stratospheric ozone to 27-day solar ultraviolet variations are as follows: (1) the amplitude of the column ozone response and whether it is consistent with the predictions of current two-dimensional stratospheric models and (2) whether the ozone profile response in the upper stratosphere differed appreciably during the solar cycle 22 maximum period (around 1990) as compared with the solar cycle 21 maximum period (around 1980). To investigate these issues, two separate 4-year intervals (1979–1982 and 1989–1992) of daily zonal mean Nimbus 7 Total Ozone Mapping Spectrometer, Nimbus 7 solar backscattered ultraviolet (SBUV), and/or NOAA 11 SBUV/2 data for tropical latitudes (30°S to 30°N) are analyzed using cross correlation and cross-spectral and regression methods. The Mg II core-to-wing ratio is employed as a measure of solar UV variations near 200 nm. Results show that the mean tropical column ozone sensitivity (percent change of ozone for a 1% change in solar flux) is 0.09±0.01 at a lag of 4–6 days during both intervals and is approximately consistent with model predictions. Ozone profile sensitivities and phase lags are also in agreement between the two 4-year intervals when statistical uncertainties and differences in data processing algorithms are considered.