Evaluation of relative aerosol abundance and effective radius of particles in the atmosphere of Uranus.

Residual intensities of the Raman lines at λλ398.9, 402,6, and 406.3 nm in the spectrum of Uranus were analysed within the framework of the model of a homogeneous semi-infinite gas-aerosol layer. The relative aerosol abundance was obtained as a function of the asymmetry parameter of the Henyey-Greenstein phase function, and of the effective radius of particles (in the case of real phase functions). The aerosol abundance in the atmosphere of Uranus is shown to be significantly lower in 1961 - 1973 than in 1981 - 1983. Comparison of relative aerosol abundances found with the Raman lines and with the absorption bands of methane at λλ509 and 576 nm gives the value of the effective radius of particles r_eff = 0.30±0910 μm. The ratio of the volume scattering coefficients for gas and gas+aerosol had values of 0.98 - 0.99 and 0.10 - 0.30 near λ400 nm for the first and second periods of observations, respectiveley, and the specific abundances of methane were 0.008±0.001 and 0.010±0.003 for the same periods.