Vertical cloud structure of the 2009 Jupiter impact based on HST/WFC3 observations

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2012-11, Vol.221 (2), p.1061-1078
• Main Authors: Pérez-Hoyos, S., Sanz-Requena, J.F., Sánchez-Lavega, A., Wong, M.H., Hammel, H.B., Orton, G.S., de Pater, I., Simon-Miller, A.A., Clarke, J.T., Noll, K.
• Format: Article
• Language: English
• Subjects: Aerosols; Astronomy; Atmospheres, Structure; Clouds; Density; Earth, ocean, space; Exact sciences and technology; Impact processes; Jupiter; Jupiter, Atmosphere; Optical thickness; Reflectivity; Refractivity; Solar system; Wavelengths
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2012.10.012

► HST WFC3 calibrated images have been used to study the 2009 impact. ► We find a strong disturbance in the aerosol density and absorption. ► Horizontal and temporal evolution of the aerosols has been also characterized. ► Typical time-scale for evolution of the parameters is about 10days. ► Most results resemble those retrieved for the SL9 fragment H. The impact of a body of unknown origin with Jupiter in July 2009 produced an intense perturbation of the planet’s atmosphere at the visible cloud levels. The vertical cloud structure was deeply affected by the presence of a strongly absorbing dense aerosol layer that was expanded steadily by advection in the local winds. We observed this phenomenon at high spatial resolution with the Hubble Space Telescope in July, August, September and November 2009 using the Wide Field Camera 3. In this work, we present radiative transfer modeling of the observed reflectivity in the wavelength range from the near UV (200nm) to near IR (950nm) range. The geometric and spectral variations of reflectivity give information on the main particle properties (optical thickness, size, and imaginary refractive index). The observations can be fitted by introducing small particles into the stratosphere with an optical thickness, at a wavelength of 400nm, ranging from 0.5±0.2 (center of the Impact Cloud) to 0.17±0.03 (impact periphery). Similar effects are detected in the troposphere; the disturbance increases the particle density at all detectable atmospheric levels, with a total aerosol column density of 5±2×109cm−2. The imaginary refractive indices of the aerosol were also substantially altered, with values of mi∼0.015 at UV wavelengths, resembling the absorption spectrum of absorber candidates previously proposed for SL9. We find a typical e-folding temporal scale of 10±3days in the most rapidly evolving region of the Impact Cloud.