Exoplanetary Atmospheric Characterization Using Polarimetry and Other Radiative Transfer Modeling Problems

Citation

Kopparla, Pushkar (2018) Exoplanetary Atmospheric Characterization Using Polarimetry and Other Radiative Transfer Modeling Problems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/bc0z-ej27. https://resolver.caltech.edu/CaltechTHESIS:04282018-222603635

Abstract

This thesis deals with a pair of current problems with the remote sensing of planetary atmospheres. First is the modeling of polarization of scattered light from the atmospheres of exoplanets. With the first such observations becoming possible in the last year, there is a need to understand what these measurements actually mean. To that end, we developed families of radiative transfer models that simulate polarized phase curves for different atmospheric scenarios on hot Jupiters. These models were then used in the interpretation of scattered light from HD 189733b and WASP 12b, two hot Jupiter exoplanets, to determine their albedos and gauge what type of scattering particles might be present in their atmospheres. The last part of this half deals with observing oceans on distant Earth-like exoplanets using polarization from glint off the water surface. Though this measurement is not possible with current telescopes, but it may become accessible in the next decade with a slew of high powered ground and space telescopes in the pipeline.

The second half of the thesis is devoted to the development of a fast radiative transfer model. The goal of this model is to be able to process the massive amounts of data coming in from Earth observing satellites such as GOSAT and OCO-2 in a timely and accurate manner. We refined the principal component analysis based fast radiative transfer model to be accurate enough to retrieve carbon dioxide concentrations to the part per million accuracy that is necessary to track spatial and temporal changes in this important greenhouse gas.

Thesis Files