Angular momentum exchange between the atmosphere/hydrosphere and interior of Saturn's moon Titan and its influence on Titan's rotation

土星最大的卫星土卫六拥有稠密的大气和含碳氢化合物的水循环。因此，通过与地球的类比，可以预期大气和水圈的重新分布和运动所引起的旋转速率和旋转轴摆动的时间变化。卡西尼号航天器最近的观测首次证明了土卫六存在理论预测的大范围可变自转，为研究地球物理流体与土卫六内部的力学耦合提供了可能。该项目旨在全面和定量地评估土卫六大气层/水圈与内部之间的角动量交换以及土卫六在季节时间尺度上的旋转响应。降水和极地湖泊的存在所暗示的大气运动和质量负荷以及碳氢化合物水文将被量化。考虑不同的内部模型，研究了角动量传递对内部耦合的敏感性。模型结果将与卡西尼号正在进行的大地测量结果进行比较，以约束土卫六的大气角动量收支，但约束很差。

Saturn’s largest moon Titan possesses a dense atmosphere and a hydrological cycle with hydrocarbons. Therefore, temporal variation in the rotation rate and wobble of the rotational axis by the redistribution and motion of the atmosphere and hydrosphere can be expected by analogy with the Earth. Recent observations by the Cassini spacecraft show first evidence of a large variable rotation of Titan as theoretically predicted and open the possibility to investigate the mechnical coupling between the geophysical fluid and interior. This project aims at comprehensive and quantiative assessment of the exchange of angular momentum between the atmosphere/hydrosphere and the interior of Titan and the rotational response of Titan on seasonal timescales. Atmospheric motion and mass loading together with hydrocarbon hydrology, as implied by the precipitation and the existence of polar lakes, will be quantified. The sensitivity of the angular momentum transfer to the internal coupling in the interior will be investigated considering different interior models. Model results will be compared with ongoing geodetic measurements by Cassini to constrain the yet poorly constrained atmospheric angular momentum budget of Titan.