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A Raman lidar was developed to observe vertical profiles of water vapor, temperature and aerosols. The lidar system can detect signal from 5 detectors simultaneously. Two vibrational Raman backscattering echoes from H 2 O and N 2 (or O 2 ) excited by Nd:YAG 3rd harmonics wavelength (355 nm) are used to observe the profiles of water vapor mixing ratio and atmospheric temperature (or density). Nd:YAG fundamental and 2nd harmonics wavelengths (1064 and 532 nm) are used to observe backscattering coefficient profiles of aerosols and clouds at these wavelengths. The scattering at 532 nm is observed in parallel and perpendicular components corresponding to the linear polarization plane of the transmitted linearly-polarized laser pulse to observe depolarization ratio profiles. Observed water vapor and temperature distributions coincide with the simultaneously observed radiosonde sounding data excellently. The Raman lidar makes it possible to observe the vertical profiles of water vapor, temperature, aerosols, and clouds simultaneously.

The J= 6 1,5 -6 0,6 (110.836 GHz) line of strato-mesopheric ozone has been measured employing a millimeterwave ozone sensor equipped with an SIS mixer receiver. The receiver noise of the SIS mixer is 34 K (SSB), and the spectrometer covers 70 MHz with a frequency resolution of 35 kHz at the present. From these observations, diurnal and seasonal variations of mixing ratio of day and night, and the day/ night ratio of mixing ratio are discussed.

The depolarization ratio of atmospheric molecules was estimated to be 0.021 on the basis of regression analysis of total depolarization ratio and scattering ratio of atmospheric aerosols measured by a lidar in spring, 1994.

We propose a new analytical procedure to derive the scattering parameter S (=extinction/backscattering ratio) of the optically thin cloud using the difference in the attenuation of two returned signals measured by a lidar. In the procedure, there is a assumption that the aerosol layers below the cloud layer do not change during the observation, and a value of backscattering coefficient at a height above the cloud layer is necessary. The former assumption is different from that of the Fernald's method in which the scattering parameter is assumed to be a constant value in itself in order to derive the extinction coefficient profile. The sensitivity test for the procedure shows that the errors in S increase in accordance with the decrease in the value of S. It also shows that if the absolute values of the difference in the scattering ratio of the cloud used for the derivation of S are equal, the errors in S are very similar to each other no matter how the optical thickness of the cloud is. The error increases in accordance with the decrease in the difference in the scattering ratio.

Growth and sedimentation of type-I polar stratospheric clouds (type-I PSCs) particles including nitric acid are examined using a numerical model. The PSCs particles which grow in the upper particle layer have enough large size (-10μm) to descend rapidly to the tropopause within several days. In the lower part of PSCs layer, evaporation of HNO3 from particulate matter occurs and acts as source of HNO3 vapor. From view point of stratospheric HNO3 distribution, the particle sedimentation effectively functions as vertical transport mechanism of HNO3 vapor from the upper PSCs layer to the lower layer and/or to the troposphere.

Aerosol parameters (size distribution, refractive index, and vertical concentration) were estimated from upwelling radiance measurements (over Ise Bay, Nagoya Japan on December 5, 1986) from an airborne platform. The modified adding method and multi-dimension regression method used for data reduction are useful techniques for remote sensing of atmospheric aerosols. The parameters estimated showed good agreement with typical urban atmospheric aerosols: a size distribution of 3.7×105×r-5.1 (particles/μm/m3) and a refractive index of 1.42+0.0069i.

Lidar measurements on stratospheric aerosols at Syowa Station (69°00′S, 39°35′E) showed that decay of the volcanic disturbance from Mt. El Chichon was superimposed on the winter enhancement (Polar Stratospheric Clouds; PSCs). The decay time scale of the disturbance was about 23 months when we approximated the decay pattern of April 1983-October 1985 (winter measurements were not used) by an e-folding decay function, but the time was about 10 months (or smaller) in the winter of 1983. These time scales suggest that decay of the volcanic disturbance was possibly affected by PSCs activities and the year-to-year change in the length of the cold season of the Antarctic stratosphere. The PSCs event may act as an effective loss of volcanic materials from the Antarctic stratosphere.

The measurements on polar stratospheric aerosol particles using lidar and meteorological sonde at Syowa Station (69°00′S, 39°35′E), Antarctica revealed that the content of stratospheric aerosols noticeably increased in winter when atmospheric temperature frequently fell down to about -80°C in the lower atmosphere, and that the depolarization ratio of the backscattered light from the enhanced stratospheric aerosols also has very large value (at least larger than 0.5 during the fully developed enhancement period).

Balloon measurements on stratospheric aerosol made at Syowa Station, Antarctica in 1983 and 1985 suggested a volcanic effect of the El Chichon eruption of 1982 on the Antarctic stratosphere in 1983. The measurements in October 1983 and 1985 showed that the “year to year” cooling of the spring stratosphere also influenced the stratospheric aerosol content. Size distributions measured in the early winter of 1983 and 1985 indicated that fine particle formation was one possible process forming the winter enhancement of stratospheric aerosols (Polar Stratospheric Clouds, PSCs), in addition to the growth of preexisting particles.

The CO2 density profile is decided using the photochmical-eddy diffusion model, and the cooling rate of CO2 15μ band in the lower thermoshere is discussed. These results show that the cooling rate of 15μ band decreases somewhat in comparison with the estimation using the assumption of constant mixing ratio of CO2. The O2(1Δg) density profile which is simultaneously calculated has small second peak near 85km.

Total depolarization ratio has been used to detect nonspherical particles in the stratosphere. This parameter is effective only when the mixing ratio of the particles is enough high. Particle depolarization ratio (Dp) is compared with the total depolarization ratio (D) on the basis of the lidar measurements made at Nagoya, Japan, during the post-El Chichon period. The comparison suggests that the particle depolarization ratio is more effective than the total depolatization ratio when the mixing ratio is lower than about one.