Abstract
Observations of atmospheric ozone and nitrous oxide were performed with a laser heterodyne spectrometer using a tunable diode laser as a local oscillator at Sendai (38°15'N, 140°51'E), Japan from November 1988 to June 1989. The absorption line spectra measured with ultra high resolution of 0.0013 or 0.0027 cm-1 (40 or 80 MHz) were inverted by a conventional inversion method to retrieve vertical distribution profiles. The observed altitude range is from 5 to 30 km for ozone and from 1 to 35 km for nitrous oxide and the vertical resolution is∼5km. Total column densities were also obtained by integrating the vertical profiles.
Errors in the retrieved mixing ratio profiles were estimated by computer simulations for all the plausible causes: ≤10% arising from uncertainties in line parameters, ∼3% from random noise in the spectra when SNR=500, and ≤3% from difference between model and actual temperature profiles. For total column densities, the random error is ≤3%, while systematic error due to uncertainty in the line strength is ≤10%.
The retrieved vertical profiles of ozone from January to June 1989 show seasonal and day-to-day variations usually seen in middle latitudes. The total column densities were compared with those measured by Dobson spectrophotometers at Tateno and Sapporo. The result is consistent with the latitudinal dependence of total column density of ozone. The vertical profiles of nitrous oxide were also obtained by the same procedure as for ozone. The result for nitrous oxide agrees with the data obtained by a balloon observation at Sanriku (39°09'N, 141°49'E).
