Author ORCID Identifier:

https://orcid.org/0009-0003-9716-8968

Date of Graduation

5-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Space & Planetary Sciences (PhD)

Degree Level

Graduate

Department

Space & Planetary Sciences

Advisor/Mentor

Chevier, Vincent

Committee Member

Theiss, Hank

Second Committee Member

Tullis, Jason

Third Committee Member

Dixon, John

Fourth Committee Member

Aly, Mohamad

Fifth Committee Member

Hoang Ngan Le, T.

Keywords

Atmosphere; Geomorphology; Mars; Planetary Science; Titan

Abstract

This dissertation investigates a central question: How do planetary boundary layer processes manifest in observable surface geomorphology, and how can planetary imagery be used to quantify those effects? The planetary boundary layer (PBL) governs near-surface exchanges of momentum, heat, and volatiles, yet direct atmospheric measurements remain spatially and temporally limited on most planetary bodies. By analyzing geomorphic features preserved in high-resolution imagery, this work quantifies how boundary-layer processes leave measurable signatures on planetary surfaces. For Mars, high-resolution images from the Mars Reconnaissance Orbiter (MRO) HiRISE instrument were used to map CO2 sublimation features, or Swiss Cheese Features (SCFs), on the South Polar Residual Cap. Object-based image analysis within a GIS framework enabled systematic delineation of pit geometries, which were then incorporated into Monte Carlo sublimation modeling to estimate growth rates and initiation ages. Modeled initiation ages indicate that actively expanding SCFs are geologically young features, with characteristic persistence timescales of approximately ~20 to ~400 Earth years and weakly constrained extrapolations extending to at most ~500 Earth years. These results demonstrate that modern boundary-layer forcing drives ongoing, localized CO2 mass loss independent of the seasonal condensation--sublimation cycle. For Titan, Cassini Ku-band RADAR observations of the Belet Sand Sea were analyzed along multiple transects to investigate radar backscatter behavior and constrain surface and subsurface scattering mechanisms. Five scattering models were implemented: Physical Optics, Geometric Optics, the Integral Equation Model (IEM), a two-layer IEM, and a volume scattering model. Surface-only models produced poor fits, particularly in flat interdune and crest regions. The volume and two-layer models yielded the lowest RMSE values across all transects, indicating vertically heterogeneous or layered internal dune structures likely driven by porosity or compositional stratification. None of the models fully reproduced quasi-specular returns observed on slope-facing surfaces. Although Mars and Titan differ markedly in atmospheric composition, density, and circulation regime, both worlds show that PBL dynamics directly drive measurable geomorphic change. Together, these results emphasize the planetary boundary layer as the physical interface linking atmospheric motion to surface evolution across planetary environments.

Download

Share

COinS