眾所皆知，全球氣候變遷造成世界各國的夏季氣溫屢創新高，導致南北極融冰速率增加。依據1994 - 2017年間的衛星數據，全球大約損失了28兆噸冰，而格陵蘭和南極冰蓋的融化速度最快。其研究顯示：由1990年代的每年0.8兆噸增加到2017年的每年1.2兆噸。大約2/3的融冰由於大氣暖化引起，1/3則由於海水變暖造成。直接導致全球海水水位上升，各國沿海地區淹水機率上升。但目前歐美各國科學家所發展的模式預測之浮冰溶解速率與實際觀測之溶冰速率有很大的差異，其中一項便是波浪、洋流對於浮冰溶解速率的影響被嚴重低估。本研究利用水槽實驗及數值模式探討浮冰在淡水和鹽水恆定水流及波浪中的融冰過程、以及浮冰周圍的水溫邊界層，並採用計算流體力學數值模式來釐清影響融冰速率的關鍵參數。實驗結果顯示：融冰速率與水冰界面熱傳速率成正比，而熱傳速率又和水流流速成線性正比，故可由水流的雷諾數來預測不同流速下的浮冰融化速率。且在相同流速下，由於淡水和鹽水的熱物理性質差異，海水的鹽度會增加水與冰塊之間的熱量傳遞，這表示鹽水中浮冰的溶化速率會略大於淡水中浮冰的溶化速率。;It is well known that global warming has caused rising temperatures around the world and ice melting in the Arctic and Antarctic. The ice melting between 1994 and 2017 has caused the global sea level to rise by 35 mm. However, there is a substantial discrepancy between the melting rate predicted by models and the actual melting rates observed in the Arctic Sea. One of the reasons for this difference is that the effects of ocean currents and surface waves on the melting rate of ice floes are under-estimated. This study employs laboratory experiments and a Computational Fluid Dynamics (CFD) model to investigate the melting process of ice floes caused by surface waves and the temperature boundary layer around floating ices. The experimental results indicate that the melting rate is linearly proportional to the current velocity. In other words, the convective heat transfer coefficient of the ice/water interface increases as the water velocity and the Reynolds number increases. In addition, the melting rate of ice in salty water is slightly greater than that in freshwater. The NCU model developed in this study can be used to predict the melting rates of floating ice under different current velocities.
