Titan is the solar system's second largest moon, a world both familiar and eerily alien, where a hazy atmosphere conceals a surface topography of hydrocarbon dunes and methane rivers and seas. Frequently described as the solar system body most analogous to Earth, it is the destination of NASA’s Dragonfly mission, scheduled to arrive in 2034, which will deploy a rotorcraft to analyze samples of complex atmospheric chemistry and varied surface composition.
In this senior capstone project for the Department of Physics, we construct an energy balance model (EBM) to simulate and investigate Titan’s climate, specifically the mechanisms driving global energy and moisture transport. Titan is the only other world in the solar system to feature an active hydrological cycle, a process of constant interaction between the atmosphere, surface and subsurface that circulates and replenishes liquid methane through processes of evaporation and precipitation. One of Titan’s most intriguing unexplained features is the confinement of all filled lake and sea basins to latitudes poleward of 55 degrees. Such distribution, which leaves equatorial and mid latitudes arid, implies pole-to-pole transport of moisture governed by seasonal and orbital cycles. Given the polar concentration of surface liquid, Titan’s global relative humidity is much greater at high latitudes than low, in an inversion of the humidity profile observed on Earth.
This paper realizes a one-dimensional model of the latitudinal dependence of energetic and hydrological processes, allowing the sensitivity of their parameters to be explored at low computational costs. The model is calibrated on known climatological results for energy distribution on Earth, then applied to Titan and adjusted to understand the influence of certain free parameters whose true values are unknown. By numerically integrating differential equations that evaluate moist static energy flux and its relationship to solar heating, the Titan version accurately replicates known temperature, energy, and moisture profiles. Implementing a recursive feedback function, we show that the model permits the natural emergence of a convergent solution for the relative humidity profile, matching that observed by data. The sensitivity of this profile is also analyzed, and the physical processes behind its response explored. By illuminating the intuition behind the planetary constraints governing moisture distribution, the model provides a flexible, accessible starting point for further investigation of Titan’s energetic processes.
All code, reports, figures, and consulted resources can be found in this repository.