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.
展开▼
