Gross assessment of the dynamical impact of numerous power-generating sailing ships on the atmosphere and evaluation of the impact on tropical cyclones

抄録

The use of massive sailing ships has been proposed as a means of acquiring renewable energy. It has also been proposed that such ships can be used to reduce the intensity of tropical cyclones (TCs). Here we propose a basis for evaluating the dynamical impacts of numerous sailing ships on the atmosphere. The key parameter is the total sail area per unit horizontal area (referred to as β), which is proportional to the number of ships in the region of interest. From β, the enhancement in the effective surface drag can be evaluated. The maximum potential intensity theory for TCs predicts that, under ideal environmental conditions, the steady-state TC intensity decreases inversely to the drag enhancement if the ship-induced change in the effective enthalpy transfer is much weaker. For example, if β is 0.04%, the potential intensity in terms of squared maximum wind can be decreased by around 10%. The effect of the directional drag from the use of aerodynamic lift in sail operations is also formulated, and its impact on TCs is evaluated by using a slab boundary-layer approximation. Sails' effects on air-sea interaction are briefly discussed, and further studies needed are envisioned.