Response of Ganga-Brahmaputra river plume to wind forcing in the Bay of Bengal is studied using a numerical ocean circulation model. Four different wind forcing scenarios, namely, winds over the entire model domain, no winds anywhere over the model domain, winds over Equatorial Indian Ocean only and winds over Bay of Bengal only, are considered. Model simulations are carried out in an idealized setting where forcing from other rivers and precipitation is ignored. Despite the absence of this forcing, model captures observed phases of Ganga-Brahmaputra river plume, seasonal cycle of sea surface temperature and spatio-temporal structure of East India Coastal Current (EICC) reasonably well. Horizontal structure of the plume is investigated using surface salinity, surface currents and freshwater thickness obtained from the simulation that includes Ganga-Brahmaputra river discharge and winds over the entire model domain. The plume spreads upstream (eastward) but remains confined to the coast in northern bay during spring. During summer monsoon, plume spreads southward along the east coast of India and subsequently southeastward over the open bay and reaches the northern tip of Andaman islands by the end of October. During winter monsoon, the plume flows southward, assisted by EICC along the east coast of India and recedes northward in the central bay. In the absence of winds, the plume flows southward along the coast of India throughout the year. Equatorial winds force the plume farther (compared to no winds case) southward along the coast of India prominently in the winter monsoon. Local winds control the horizontal structure of the plume in the bay as they produce the seasonal structure that closely resembles that produced by the winds over the entire model domain. Momentum balance of the plume reveals that geostrophy controls the westward drift of the freshwater around the river mouth. Wind friction and associated Ekman flow are important in the upstream spreading of the plume during spring and in the eastward expansion over the open bay during summer monsoon.

利用数值海洋环流模型研究了孟加拉湾恒河-布拉马普特拉河羽流对强迫的响应。考虑了四种不同的风力情景，即整个模型域上的风，模型域上没有任何风，仅赤道印度洋上的风，以及孟加拉湾上的风。在理想化的环境中进行模型模拟，其中忽略了来自其他河流的强迫和降水。尽管没有这种强迫，该模型仍能很好地捕获恒河-布拉马普特拉河羽流的观测阶段，海面温度的季节性周期和东印度洋海流（EICC）的时空结构。使用表面盐度研究烟羽的水平结构，从包括Ganga-Brahmaputra河流排放和整个模型域的风在内的模拟中获得的地表水流和淡水厚度。羽流向上游（向东）扩散，但在春季期间仍局限于北部海湾的海岸。在夏季季风期间，烟羽沿印度东海岸向南扩散，然后在开阔海湾向东南扩散，并于10月底到达安达曼群岛的北端。在冬季季风期间，羽流向南流动，在EICC的帮助下沿印度东海岸，并在中央海湾向北后退。在没有风的情况下，羽流全年沿印度海岸向南流动。赤道风在冬季季风中突出地使羽流沿印度海岸向南延伸（与无风情况相比）。局部风控制海湾中羽流的水平结构，因为它们产生的季节结构与整个模型域中的风所产生的季节结构非常相似。羽流的动量平衡表明，地球动力学控制着河口周围淡水的向西漂移。风摩擦和相关的Ekman流量在春季春季羽流的上游扩散以及夏季季风期间在空旷海湾的东扩中很重要。