Brightness power spectral distribution and waves in Jupiterʹs upper cloud and hazes

In this work we analyze the spatial structure of Jupiterʹs cloud reflectivity field in order to determine brightness periodicities and power spectra characteristics together with their relationship with Jupiterʹs dynamics and turbulence. The research is based on images obtained in the near-infrared ( ∼ 950 nm ), blue ( ∼ 430 nm ) and near-ultraviolet ( ∼ 260 nm ) wavelengths with the Hubble Space Telescope in 1995 and the Cassini spacecraft Imaging Science Subsystem in 2000. Zonal reflectivity scans were analyzed by means of spatial periodograms and power spectra. The periodograms have been used to search for waves as a function of latitude. We present the values of the dominant wavenumbers for latitude bands between 32° N and 42° S. The brightness power spectra analysis has been performed in the meridional and zonal directions. The meridional analysis of albedo profiles are close to a k −5 law similarly to the wind profiles at blue and infrared wavelengths, although results differ from that in the ultraviolet. The zonal albedo analysis results in two distributions characterized by different slopes. In the near infrared and blue wavelengths, average spectral slopes are n 1 = − 1.3 ± 0.4 for shorter wavenumbers ( k < 80 ), and n 2 = − 2.5 ± 0.7 for greater wavenumbers, whereas for the ultraviolet n 1 = − 1.9 ± 0.4 and n 2 = − 0.7 ± 0.4 , possibly showing a different dynamical regime. We find a turning point in the spectra between both regimes at wavenumber k ∼ 80 (corresponding to L ∼ 1000 km ) for all wavelengths.