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Geophysical Research Letters

Stratospheric ozone profile and total ozone trends derived from the SAGE I and SAGE II data



SAGE I/II ozone data from the period 1979–1991 have been used to derive global trends in both stratospheric column ozone and as a function of altitude. A statistical model containing quasibiennial, seasonal, and semiannual oscillations, a linear component, and a first-order autoregressive noise process was fit to the time series of SAGE I/II monthly zonal mean data. The linear trend in column ozone above 17 km altitude, averaged between 65°S and 65°N, is −0.30 ± 0.19%/year or −3.6% over the time period February 1979 through April 1991. The data further show that the column trend above 17 km is nearly zero in the tropics and increases towards the high latitudes with values of −0.6%/year at 60°S and −0.35%/year at 60°N. Both these results are in agreement with the recent TOMS results. Furthermore, the profile trend analyses show the column ozone losses are occurring below 25 km, with most of the loss coming from the region between 17 and 20 km. Negative trend values on the order of −2%/year are found at 17 km in mid-latitudes.

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