Jovian chromophore characteristics from multispectral HST images

The chromophores responsible for coloring the jovian atmosphere are embedded within Jupiter's vertical aerosol structure. Sunlight propagates through this vertical distribution of aerosol particles, whose colors are defined by ϖ₀( λ), and we remotely observe the culmination of the radiative transfer as I/ F( λ). In this study, we employed a radiative transfer code to retrieve ϖ₀( λ) for particles in Jupiter's tropospheric haze at seven wavelengths in the near-UV and visible regimes. The data consisted of images of the 2008 passage of Oval BA to the south of the Great Red Spot obtained by the Wide Field Planetary Camera 2 on-board the Hubble Space Telescope. We present derived particle colors for locations that were selected from 14 weather regions, which spanned a large range of observed colors. All ϖ₀( λ) curves were absorbing in the blue, and ϖ₀( λ) increased monotonically to approximately unity as wavelength increased. We found accurate fits to all ϖ₀( λ) curves using an empirically derived functional form: ϖ₀( λ) = 1 - A exp(- Bλ). The best-fit parameters for the mean ϖ₀( λ) curve were A = 25.4 and B = 0.0149 for λ in units of nm. We performed a principal component analysis (PCA) on our ϖ₀( λ) results and found that one or two independent chromophores were sufficient to produce the variations in ϖ₀( λ). A PCA of I/ F( λ) for the same jovian locations resulted in principal components (PCs) with roughly the same variances as the ϖ₀( λ) PCA, but they did not result in a one-to-one mapping of PC amplitudes between the ϖ₀( λ) PCA and I/ F( λ) PCA. We suggest that statistical analyses performed on I/ F( λ) image cubes have limited applicability to the characterization of chromophores in the jovian atmosphere due to the sensitivity of I/ F( λ) to horizontal variations in the vertical aerosol distribution.