A cold water region will occur in the east entrance area of Qiongzhou Strait when upwelling develops off the northeast coast of Hainan Island. The effect of topography on this cold water region was investigated by combining satellite observations and numerical simulations. Multi-source high-resolution remote-sensed sea surface temperature images revealed that the western periphery of the cold water region frequently occurred at a quasi-fixed location with similar jagged structure. Compared with observations, the numerical model employed in this study could satisfactorily simulate the intense tidal currents in the strait, and reasonably reproduce the jagged western periphery of the cold water region. Under strong westward tidal flow, the cold upwelling water intruded deeply into the interior strait, whereas under sustained eastward tidal currents, much stronger tidal currents occurred where there were deeper waters connecting the inner strait, therefore the cold upwelling water faded towards east faster and formed the concave parts (looking in east-to-west direction) of the western periphery of the cold water region; conversely, convex parts would develop over the adjacent shallower shoals. The eastward movement of the cold water was dominated by topography-modified tidal currents, and only after sustained eastward tidal currents (usually in the second half or near the end of the eastward tidal current phase), the western periphery of the cold water region would occur at a quasi-fixed location with similar jagged shape. Moreover, the development of the upwelling off the northeast coast of Hainan Island, which was the precondition of the cold water region, was found to be mainly driven by sustained SE ~ S winds.

当海南岛东北沿海发生上升流时，琼州海峡东入口区域将出现一个冷水区。通过结合卫星观测和数值模拟研究了地形对这一冷水区域的影响。多源高分辨率遥感海表温度图像显示，冷水区的西部边缘经常发生在具有类似锯齿状结构的准固定位置。与观测值相比，本研究采用的数值模型可以令人满意地模拟海峡的强烈潮流，并合理地再现了冷水地区锯齿状的西部边缘。在强烈的西移潮汐作用下，上升的冷水深深地侵入内海峡，而在持续的东移潮汐作用下，在连接内海峡的较深水域发生了更大的潮流，因此，上升流冷的水更快地向东消退，并形成了冷水区西部外围的凹形部分（从东西方向看）；相反，凸部将在相邻的浅滩上形成。冷水的向东运动受地形变化的潮流所控制，只有在持续的向东潮流（通常在东向潮流阶段的后半期或末期）之后，冷水区域的西部外围才会出现发生在具有类似锯齿形的准固定位置。此外，海南岛东北沿海上升流的发展是冷水区的前提，