Normal modes and resonance in Ontario Lacus, a hydrocarbon lake of Titan

The natural modes of Ontario Lacus surface oscillations, the largest lake in Titan's southern hemisphere, are simulated and analysed as they are potentially of broad interest in a variety of dynamical researches. We found that tidal forces are too low in frequency to excite the (barotropic) normal modes. Broadband wind forcing likely spans the resonant frequencies. High wind speed, which could be encountered under episodic phenomenon such as storms, would be required to significantly excite the normal modes. While the slower baroclinic normal modes could more easily be resonantly forced by the low-frequency tidal forces, addressing this issue demands unavailable information about the lake stratification.