Steven L. Taylor

Observations of "Hystereris" in Backscattered Ultraviolet Ozone Data

Abstract Satellite measurements using the backscattered ultraviolet technique provide a powerful method for the observation of stratospheric ozone. However, rapid input signal variations over three to four orders of magnitude in several minutes can lead to problems with instrument response. Inflight data have recently been used to characterize a “hysteresis” problem on the NOAA-9 SBUV/2 instrument, which affects measurements made shortly after emerging from darkness. Radiance values observed under these conditions can be up to 2%–3% lower than expected. A correction has been derived for NOAA-9 data that is solar zenith angle dependent and varies in amplitude and time. Typical changes to affected polar total ozone values are on the order of 1% but can reach 5% in some cases. Profile ozone changes are altitude dependent, with maximum values of 4%–5% at 1 hPa. The NOAA-11 and NOAA-14 SBUV/2 instruments have a much smaller hysteresis effect than that observed for NOAA-9 SBUV/2 due to a change in photomultipli...

Role of multiple scattering in ozone profile retrieval from satellite measurements in the ultraviolet

The retrieval of the ozone profile from satellite ultraviolet measurements can be extended to greater depths when multiple scattering is taken into account. The sensitivity of the multiple-scattered wavelength radiances to geophysical variables are discussed and results of profile inversions of Nimbus 4 backscatter ultraviolet data for coincident ground-truth measurements with and without multiple scattering are presented .

TOMS profile shape error estimates at high latitude

The Total Ozone Mapping Spectrometer (TOMS) ozone measurement is derived by comparing measured backscattered ultraviolet (BUV) radiances with theoretical radiances which are pre- computed using standard climatological ozone profiles and stored in a look-up table. Profile shape errors occur in this algorithm at high latitudes (or more specifically, high optical path lengths) when the actual vertical ozone distribution differs significantly from the standard profile used in constructing the tables. These errors are estimated using sensitivities derived from radiative transfer calculations and measurements of the actual ozone profile from Solar Backscatter Ultraviolet (SBUV) and Balloonsonde. These estimates include a short term uncertainty with a standard deviation of 10% in total column ozone amount as well as a systematic error in the long-term trend at very high solar zenith angles. At the maximum retrieval solar zenith angle of 88 degrees, these calculations indicate that TOMS long-term ozone depletions are over-estimated by 5%/decade.