Observations of Ozone Mixing Ratio by Nagoya 4m Millimeterwave Telescope.

Abstract

The J = 6(1,5)-6(0,6) (110.8359 GHz) line of mesospheric ozone has been observed by employing the 4 m 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 4 K refrigerator and its receiver noise is 23 K (DSB). Spectroscopy is through a 1024 channel acousto-optical spectrometer with a frequency resolution of 50 kHz. The frequency shift and the time intervals for the frequency switching are 18 MHz 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 0.14 K in 50 kHz 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 6.4 MHz. 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(alpha)[(R(m)(h - H(m))/alpha] by BRILLET (1989) but the one in midnight deviate from the model above 60 km.