PhD Defense Announcement - Kyeungwoo Cho

ADVANCING GLOBAL ECO-HYDROLOGICAL MONITORING: AN INTEGRATED PHYSICAL MODELING FRAMEWORK FOR MULTI-SENSOR REMOTE SENSING

SEB 122

2026-11-19 2:00 PM EST

Rafael L. Bras

Passive microwave remote sensing offers extensive coverage of terrestrial water dynamics, yet reliable retrieval of hydrological variables remains challenging due to the complex interactions among soil, vegetation, and snow within the observed radiometric signal. This dissertation investigates an integrated physical modeling framework grounded in the Maximum Entropy Production (MEP) principle to improve the interpretation of microwave observations across heterogeneous terrestrial environments. Building upon radiative transfer theory and thermodynamically constrained energy partitioning, the MEP framework is examined for the simultaneous retrieval of soil moisture (SM) and vegetation water content (VWC). Evaluations across diverse ecosystems demonstrate strong agreement between retrieved soil moisture and ground observations, with correlations ranging from 0.74 to 0.91 at three SMAP core validation sites. Extensions of the framework reveal seasonal relationships between satellite-derived VWC and live fuel moisture in the western United States, while applications to the 2023–2024 Amazon drought identify widespread soil moisture deficits accompanied by spatially heterogeneous vegetation responses. A further extension to a two-layer snow–soil system demonstrates the potential for snow water equivalent (SWE) estimation using multi-frequency microwave observations, subject to prescribed snow properties and calibrated parameters. Together, these findings establish a physically interpretable foundation for investigating terrestrial water states through a common radiative-transfer and thermodynamic perspective. By demonstrating both the applicability and limitations of MEP-based retrievals, this dissertation contributes toward more reliable and integrated multi-sensor monitoring of terrestrial hydrological dynamics.