Titan's aerosols: Comparison between our model and DISR findings

Our model [Dimitrov, V., Bar-Nun, A., 1999. A model of energy dependent agglomeration of hydrocarbon aerosol particles and implication to Titan's aerosol. J. Aerosol. Sci. 30(1), 35-49] describes the experimentally found polymerization of C2H2 and HCN to form aerosol embryos, their growth and adherence to form various aerosols objects [Bar-Nun, A., Kleinfeld, L, Ganor, E., 1988. Shape and optical properties of aerosols formed by photolysis of C2H2, C2H4 and HCN. J. Geophys. Res. 93, 8383-8387]. These loose fractal objects describe well the findings of DISR on the Huygens probe (Tomasko, M.G., Bezard, B., Doose, L., Engel, S., Karkoschka, E., 2008. Measurements of methane absorption by the descent imager/spectral radiometer (DISR) during its descent through Titan's atmosphere. Planet. Space Sci., this issue, doi: 10.1016/j.pss.2007]. These include (1) various regular objects of R = (0.035-0.064) x 10(-6) m, as compared with DISR's 0.05 x 10(-6) m; (2) diverse low and high fractal structures composed of random combinations of various regular and irregular objects; (3) the number density of fractal particles is 6.9 x 10(6) m(-3) at Z = 100 km, as compared with DISR's finding of 5.0 x 10(6) m(-3) at Z = 80 km; (4) the number of structural units per higher fractals in the atmosphere at Z similar to 100 km is (2400-2700), as compared with DISR's 3000, and their size being of R = (5.4-6.4) x 10(-6) m will satisfy this value and (5) condensation of CH4 on the highly fractal structures could begin at the altitude where thin methane clouds were observed, filling somewhat the new open fractal structures. (C) 2007 Elsevier Ltd. All rights reserved.