Accuracy of total ozone column amounts observed with solar infrared spectroscopy

Total ozone column amounts were observed at Rikubetsu (43.5°N, 143.8°E), Japan on 90 days between May 18, 1995 and April 26, 1996 with a high-resolution infrared (IR) Fourier transform spectrometer and compared with Dobson spectrometer measurements. The sensitivities of the analysis for IR solar absorption spectra to initial profiles were examined using two kinds of initial profiles for ozone and temperature, namely monthly and yearly averages. IR/Dobson mean column ratios in the two cases were 1.02 and 1.03 and the standard deviation of the ratios were 3.7 and 4.1 %, which correspond to 14 and 16 Dobson Units. The standard deviations are smaller than or comparable to the amplitudes of the day-to-day total ozone column variations indicating that day-to-day variations can be detected using monthly or yearly averaged profiles. However, significant solar zenith angle (SZA) dependences were observed in the columns derived using yearly averaged profiles. The SZA dependence was most, significant in January and February when the ozone amount in the lower stratosphere was largest. The SZA dependence is considered to be caused by the difference between initial and actual ozone profiles.