[
    {
        "id": "thesis:18474",
        "collection": "thesis",
        "collection_id": "18474",
        "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04062026-211214699",
        "type": "thesis",
        "title": "Polar Vortices and Aerosols in the Solar System",
        "author": [
            {
                "family_name": "Chen",
                "given_name": "Sihe",
                "orcid": "0000-0002-0901-3428",
                "clpid": "Chen-Sihe"
            }
        ],
        "thesis_advisor": [
            {
                "family_name": "Yung",
                "given_name": "Yuk L.",
                "orcid": "0000-0002-4263-2562",
                "clpid": "Yung-Y-L"
            },
            {
                "family_name": "Ingersoll",
                "given_name": "Andrew P.",
                "orcid": "0000-0002-2035-9198",
                "clpid": "Ingersoll-A-P"
            }
        ],
        "thesis_committee": [
            {
                "family_name": "Batygin",
                "given_name": "Konstantin",
                "orcid": "0000-0002-7094-7908",
                "clpid": "Batygin-K"
            },
            {
                "family_name": "Yung",
                "given_name": "Yuk L.",
                "orcid": "0000-0002-4263-2562",
                "clpid": "Yung-Y-L"
            },
            {
                "family_name": "Ingersoll",
                "given_name": "Andrew P.",
                "orcid": "0000-0002-2035-9198",
                "clpid": "Ingersoll-A-P"
            },
            {
                "family_name": "Thompson",
                "given_name": "Andrew F.",
                "orcid": "0000-0003-0322-4811",
                "clpid": "Thompson-A-F"
            },
            {
                "family_name": "Li",
                "given_name": "Cheng",
                "orcid": "0000-0002-8280-3119",
                "clpid": "Li-Cheng"
            }
        ],
        "local_group": [
            {
                "literal": "div_gps"
            }
        ],
        "abstract": "<p>Polar vortex is a ubiquitous phenomenon in atmospheres of rotating planets. Formed by the interplay of planetary rotation, radiative forcing, and meridional temperature gradients, these persistent, cyclonically rotating air masses are most pronounced in the stratosphere and troposphere of planets with significant atmospheric circulation. The strength and stability of a polar vortex depend on factors such as planetary obliquity, atmospheric composition, and seasonal variations. The polar vortices have strong implications for planetary habitability: a stable polar vortex can regulate heat distribution and maintain atmospheric stability, while excessive variability can lead to extreme climate shifts.</p>\r\n\r\n<p>Aerosols - suspended particles in a planetary atmosphere -play a crucial role in shaping the dynamics and chemistry of polar vortices. These particles, which can originate from volcanic eruptions, photochemical reactions, or external sources like meteoritic dust, influence radiative transfer and cloud formation. On Earth, stratospheric aerosols, particularly sulfuric acid droplets from volcanic eruptions, can enhance the stability of the polar vortex and contribute to ozone depletion through heterogeneous chemical reactions on their surfaces. Similarly, on Titan, complex organic aerosols accumulate in its polar vortex, forming thick hazes that drive seasonal temperature asymmetries, and the study of them has important implications for the early earth, where the atmosphere was as reducing.</p>\r\n\r\n<p>Chapters 2-4 of this thesis present both experimental and numerical approaches to studying polar vortices, while Chapters 5-6 focus on the development of observational methods for aerosol characterization. Chapters 7-8 investigate the interplay between aerosols and key atmospheric processes, including photochemistry and dynamics.</p>\r\n\r\n<p>Chapter 2 examines the dynamic regimes of polar vortices using a shallow-water system, identifying the conditions under which a Jupiter-like vortex crystal structure emerges, as opposed to the merging vortices observed on Saturn and Titan. Chapter 3 introduces a numerical approach utilizing a Riemann-solver-based cubed-sphere dynamical core, which eliminates the need for polar filters in general circulation models. This method significantly improves polar resolution, enabling a more detailed investigation of polar atmospheric physics.</p>\r\n\r\n<p>Chapter 4 applies a fast Fourier optics method to Pluto, generating synthetic stellar occultation light curves from global climate models. The analysis reveals that aerosol distribution influences the observed light curves, offering insights into Pluto's unobserved terrain. Chapter 5 develops a two-step neural network framework to characterize aerosol properties in satellite-based spectra of Earth's atmosphere, enhancing the accuracy of XCO2 quantification.</p>\r\n\r\n<p>Chapter 6 investigates the previously observed bimodal distribution of Pluto's haze by coupling a photochemistry-microphysics model with the solar insolation cycle. Chapter 7 examines the origin of an exotic form of \"aerosol\" - the plume activity on Enceladus. By coupling dynamical equations governing ice movement due to tidal stresses, water transport within subsurface channels, and vapor dynamics, the model reproduces the observed time variability of Enceladus' plume, supporting the existence of a subsurface ocean beneath its icy shell.</p>",
        "doi": "10.7907/pcdd-5y77",
        "publication_date": "2026",
        "thesis_type": "phd",
        "thesis_year": "2026"
    }
]