Seasonal and interannual variations in total ozone Revealed by the Nimbus 4 Backscattered Ultraviolet Experiment

Abstract

The first 2 years of backscattered ultraviolet (BUV) ozone data from the Nimbus 4 spacecraft have been processed to a more refined level. The seasonal variations of total ozone for the period April 1970 to April 1972 are described using daily means for 10° latitude zones and a time‐latitude cross section. In addition, the BUV data are compared with analyzed Dobson data and with infrared interferometer spectrometer data also obtained from the Nimbus 4 spacecraft. A harmonic analysis was performed on the daily zonal means. Amplitudes, days of peak ozone values, and percentage of variance have been computed for the annual and semiannual waves and for higher harmonics of an annual period for the 2 years. Asymmetries are found in the annual waves in the two hemispheres, with a subtle interannual difference which may be due to changes in the general circulation. A significant semiannual component is detected in the tropics for the first year. This component appears to result from influences of the annual waves in the two hemispheres. A search for shorter periods using the harmonic analysis revealed no periodicity whose amplitude was higher than the noise level.

Detection of nighttime atmospheric scattering of lunar UV radiances by the Nimbus 4 BUV instrument

“…The statement that ozone is known to better than 50% accuracy is not based on model calculations but on observational climatology derived from many years of Dobson measure-ments [see Angell and Korshover, 1978] and 7 years of BUV observations [Hilsenrath et al, 1979].…”

Total ozone seasonal and interannual variations derived from the 7 year Nimbus‐4 BUV data set

“…London et al [1976] halve constructed hemispheric maps of monthly mean total ozone, using Dobson observations from 1957 to 1967. However, Hilsenrath et al [1979] have demonstrated with satellite data that important features were missed in the southern hemisphere because of the scarcity of observing stations. Global ozone trends have been calculated by Angell and Korshover [1978] from ground observations.…”

“…However, the parture from sinusiodal behavior of the 2, 1, and 1/2 year semiannual oscillation in the southern hemisphere mid-latiwaves. Shorter period oscillations, which may have a geophys-tudes detected by Hilsenrath et al [1979] in 2 years of data, ical correlation, such as with sotar rotation, can be better iden-persists above the noise in the longer data set. It also appears titled with techniques other than harmonic analysis.…”

“…Amplitudes of 2 year, annual, and semiannual waves, the percentage of variance contributed, and the phase (day of peak ozone value) were computed for each harmonic. The analysis procedure has been described in detail by Hilsenrath et al [1979]. Because a harmonic analysis cannot be performed accurately when there are large gaps in the data, daily zonal means in polar winter are estimated by extrapolation.…”

“…The analyses are performed by using zonal means, a convenient description for a time varying globally distributed variable that is a strong function of latitude. An analysis of BUV data for April 1970 to May 1972 was reported earlier by Hilsenrath et al [1979]. That investigation clearly and concisely revealed the asymmetry of the annual wave in the two hemispheres.…”