Near-Infrared Radiative Transfer Modelling of the Giant Planetary Atmospheres

Abstract

By their proximity, jovian planets provide the best lab to analyse their unique spectral features contributing further to the improvement of both planetary and exoplanetary atmospheric sciences.

In this thesis, VSTAR and ATMOF codes have been modified and performed to suit the spectral modelling of the jovian planets producing accurate telluric models for line removal and fitting the modelled spectra. The spectral model fits here, used for analysing different spectral features in accordance with P-T profiles, chemical composition and cloud parameters, focus on cloud base pressures and opacities in the atmosphere of jovian planets. The line-by-line radiative transfer atmospheric models presented here are innovative and novel in their concurrent analysis of the transmitted, emitted and reflected light capable of using the most powerful modelling software. The models specified here relate to the atmospheric characterisation of the giant planetary worlds in the Solar System, with potential for expanded application to planetary worlds beyond our own neighbourhood.

My models spectrally characterised the upper atmosphere of the ice giants in the NIR bands (R ~2400, 5100 and ~17800), determining their cloud optical parameters by applying three of the latest theoretical and empirical methane line datasets. Meanwhile, by calculating their D/H ratios in both methane and hydrogen, I was able to reassess their formation scenario, suggesting the formation of Uranus at a greater distance from the Sun than Neptune.

I also analysed and modelled Jupiter’s planetary disk in three NIR bands of J, H and K (R ~2400) using its various cloud particle distribution through their optical depths and base pressure ranges. In total, 153 NIR spectra indicative of 51 spectral regions on Jupiter’s disk have been modelled and characterised. The spectral regions correspond to 9 designated latitudes and 7 specified longitudes, as a function of their cloud opacity and base pressure changes. The analysis produced the global map of clouds/haze variations on Jupiter’s disk resulting in better understanding of its atmospheric characteristics, dynamics and features capable of creating a broader spectral view to contribute to the planet’s future atmospheric studies along with its giant remote cousins.