Ruby Lidar Observatiens of the E1 Chichon Dust Clouds at Tsukuba (36.1&amp;deg;N) and Comparisons with UV Lidar Measurements at Fukuoka (33.6&amp;deg;N)

The aerosol optical thickness of the atmosphere was measured using a spectropyrheliometer at Tsukuba for three winter seasons from October 1980 to March 1983. The optical thickness was abnormally large in the ('82-'83) winter, because of the enhancement of the stratospheric aerosols due to the volcanic eruptions of El Chichon.Size distributions of aerosols in the vertical air column were inferred, which show characteristic features of bimodal distribution for the pre-E1 Chichon season and power law distribution for the post-E1 Chichon season.Optical properties of the El Chichon volcanic aerosols have been estimated; the stratospheric optical thickness was about 0.1 on the wavelength average in the ('82-'83) winter, and aerosol size distributions were relatively monodispersive with a mode radius around 0.3 *m. Possible effects of the enhanced stratospheric aerosols on the solar radiation budget were estimated and compared with available observations. The El Chichon induced aerosols in the ('82-'83) winter could reduce the total solar radiation on the ground by as much as 3-4% on cloudless days, and enhance the spherical albedo by about 10%.

“…These values agree quite well with the MRI lidar observation by Uchino et al (1984) of 3.3* 10-3 SR-1 and 2.3*10-3 SR-1, respectively.…”

Section: Characteristics Of Aerosol Size Distributionssupporting

confidence: 90%

Section: Spectro-pyrheliometermentioning

confidence: 99%

Section: Characteristics Of Aerosol Size Distributionsmentioning

confidence: 99%

See 1 more Smart Citation

Atmospheric Turbidity and Aerosol Size Distribution in Winter at Tsukuba: Effects of the Eruption of E1 Chichon

Asano¹,

Sekiguchi²,

Kobayashi³

et al. 1985

“…This observation means that the variation of Ta (500) revealed in this study consists of a long-term variation due to stratospheric aerosols as a bias and a short-term variation due to ttopospheric aerosols. Compared with the height-integrated backscattering coefficient of the stratospheric aerosols observed in Japan by lidars (Uchino et al, 1984;Hayashida and Iwasaka, 1985), the long-term variation of Ta (500) seems to suggest an increase and decline of the volcanic aerosols in the stratosphere due to the El Chichon eruption. Asano et al (1985) reported the increase in Ta (500) due to the El Chichon aerosols of 0.17 in December 1982 and 0.09 in January 1983 at Tsukuba, Japan (i.e., the differences of the optical thickness from the preceding year).…”

Section: Results and Discussion A Temporal Variation O F Columnar Tomentioning

confidence: 84%

Aerosol Monitoring Using a Scanning Spectral Radiometer in Sendai, Japan

Shiobara¹,

Hayasaka

Nakajima

et al. 1991

Measurements of direct solar irradiance and sky radiance were carried out in Sendai, Japan for the period from September 1981 to May 1985 using a scanning spectral radiometer (aureolemeter). Size distributions of columnar total aerosols were retrieved by inverting both spectral optical thickness and solar aureole radiance data.The size distribution of aerosols due to the El Chichon eruption in 1982 was estimated as the difference between columnar volume spectra before and after the eruption. The results indicate that the El Chichon aerosol had a monomodal volume spectrum with a mode radius about 0.5 ,*m; their contribution to the total aerosol volume reached the maximum in the winter of 1983, i. e. December 1982 to February 1983, then gradually decaying to the normal level prior to the eruption by the spring of 1985.A seasonal model of tropospheric aerosols over Sendai was constructed by subtracting the volume spectrum of the El Chichon aerosol model from that of the columnar total aerosols, and successfully represented by a bimodal log-normal function. The aerosols in spring and summer seasons have different features in respect of volume spectra. The coarse particle mode aerosols with radii around 3 *m are predominant in spring while the accumulation mode aerosols with radii around 0.2µm are predominant in summer.

“…The weighted-mean method was used to obtain R(z) using the molecular density profile which was calculated from daily rawinsonde data at Tateno Aerological Observatory (TAO) located about 300 m from the lidar station. backscatter for the aerosols was assumed to be 50 sr at 1064 nm (Uchino et al, 1984). Figure 2 shows the vertical profiles of scattering ratio R(z) during November 18 through December 26, 1988.…”

Section: The Lidar Systemmentioning

confidence: 99%

Lidar Measurements of Stratospheric and Tropospheric Aerosols at 1064 nm Using a New and Low-Noise Photomultiplier

Uchino¹,

Takashima

Tabata³

1991

Self Cite

Using a new type of photomultiplier (PMT) tube R3236 cooled to -30*, and a photon counting method, lidar measurements of stratospheric aerosols and tropospheric aerosols above an altitude of 2.25 km were made at the fundamental wavelength of * =1064 nm of a Nd:YAG laser which is sensitive to aerosol scattering. The PMT R3236 was found to be useful even for measurements of stratospheric aerosols near the background level.The average of the integrated backscattering coefficient above tropopause was 3.3 * 10_5 sr-1 at Tsukuba (36.1*, 140.1*) during November through December 1988. Tropospheric aerosol layers in the free atmosphere were frequently observed and the altitude of the maximum scattering ratio of the aerosol layer varied for every measurement, compared with the stable stratospheric aerosol layer. Some tropospheric aerosol layers were confined by two inversion layers.