31st Annual Meeting of the DPS, October 1999
Session 51. Outer Planet Atmospheres Posters
Poster Group II, Thursday-Friday, October 14, 1999, , Kursaal Center

[Previous] | [Session 51] | [Next]

[51.05] Structures of the Jovian Upper Clouds and the Scattering Properties of Aerosol Particles

S. Itoh, T. Satoh, K. Kawabata (Science University of Tokyo)

The single scattering phase functions of Jovian aerosols, obtained by analyzing the Pioneer photometry data (Tomasko et al., Icarus 33, 558, 1978), have been widely used to investigate Jupiter's upper cloud structures. These were constructed for the blue (440 nm) and the red (640 nm), while the recent high-resolution observations extend to longer wavelengths. Since the light scattering is a function of wavelength, simply adopting the Pioneer phase functions for the longer-wavelength data could introduce systematic errors to the resulting atmospheric structures. The Pioneer phase functions are represented by a two-term Henyey-Greenstein function which carries no wavelength-dependent information. To obtain that, we therefore approximate the Pioneer phase functions using Mie scattering by spherical particles. Two sets of size distribution parameters (one for the bright zone and the other for the dark belt) and two values of refractive index (one for the blue and the other for the red) are optimized by means of the generalized data inversion technique based on the singular-value decomposition. Sufficiently good approximation is obtained if the real part of the refractive index is allowed to increase to approximately 1.5, slightly larger than the nominal value for the ammonia ice. Although no appropriate account for such a high value can be established at this stage, the effects due to non-sphericity of the ice crystals are likely to be responsible for this.

Next, we perform multiple scattering model analyses of a collection of photometry data, coverring a wide wavelength range from 220 nm to 950 nm (West, Icarus 38, 12, 1979; Tomasko et al., Icarus 65, 218, 1986; Kuehn and Beebe, Icarus 101, 282, 1993). The optical depth of the haze layer based on our analyses shows a wavelength dependence which is rather consistent with the assumption that the haze particles may also be of non-spherical shape: it decreases quite rapidly as we go toward the near-infrared wavelength.

If you would like more information about this abstract, please follow the link to http://www.ed.kagu.sut.ac.jp/~j1298607/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: j1298607@ed.kagu.sut.ac.jp

[Previous] | [Session 51] | [Next]