Observations of Ozone Mixing Ratio by Nagoya 4m Millimeterwave Telescope

抄録

The J=6_{1, 5}-6_{0, 6} (110.8359GHz) line of mesospheric ozone has been observed by employing the 4m millimeterwave telescope equipped with an Nb SIS mixer receiver of the Department of Astrophysics, Nagoya University, during 16-17 January 1990 by frequency switching mode as part of DYANA Campaign. The SIS mixer is cooled by a closed cycle 4K refrigerator and its receiver noise is 23K (DSB). Spectroscopy is through a 1024 channel acousto-optical spectrometer with a frequency resolution of 50kHz. The frequency shift and the time intervals for the frequency switching are 18MHz and 2 seconds, respectively. The integration time was 6 minutes in most of the cases. R. m. s. errors of the brightness temperature were less than 0.14K in 50kHz resolution. Successive line profiles in the dawn are illustrated to show rapid depletion of ozone in the upper mesosphere. Ozone in the upper mesosphere depletes at sunrise in mesosphere substantially within the integration time of 6 minutes. Ozone mixing ratio has been estimated from the differential brightness temperature between the successive frequency offsets of 0.0, 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4MHz. The brightness temperature at these frequency offsets are obtained from line profiles smoothed by polynomial fitting in order to reduce statistical errors. Diurnal variations of ozone mixing ratio at the various altitude are illustrated. General features of the diurnal variation agree well with ZOMMERFELDS et al. (1989). The altitude profile of the mixing ratio at noon agrees well with the formula D_m/cosh^α[(R_m(h-H_m)/α] by BRILLET (1989) but the one in midnight deviate from the model above 60km.