Abstract Energetics of semidiurnal barotropic and internal tides in the Bay of Bengal (BoB) and Andaman Sea (AS) are studied using the simulations from a high-resolution ocean general circulation model. Barotropic M 2 tide, which is the largest tidal constituent in this region, loses about 65.5 GW of energy in the BoB and AS. Most of this barotropic energy (46.5 GW) is dissipated by means of bottom friction in the shallow regions, such as the head of the bay and the Gulf of Martaban. Due to the interaction of barotropic tides with bottom topography, about one-third of the barotropic M 2 energy (19.1 GW) gets converted into internal tides and most of this conversion (84%) occurs over the Andaman–Nicobar (AN) Ridge. On the contrary to the estimates in earlier studies, our results show that a large part (59%) of this internal tide energy in the BoB and AS gets dissipated far away from the generation sites. Compared to the BoB, energy dissipation rates are found to be large over the entire AS and it could result in enhanced vertical mixing in this region. Further, analysis of the temporal variability of conversion within the model domain shows that energy conversion in the semidiurnal band varies between 11 to 27 GW over a spring–neap cycle. Seasonal variability in the stratification due to river runoff significantly changes the conversion of tidal energy at the generation sites in the northern BoB and AS. Our study revealed that westward radiating internal tides from AN Ridge undergo path alteration (refraction) due to the time-varying mesoscale circulation and such path alterations cause large intraseasonal variability in internal tide activity and redistribution of internal tide energy available for mixing in the remote areas such as the continental margins of the western BoB.

中文翻译：

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孟加拉湾和安达曼海半日内潮汐的能量学和时空变化

摘要 利用高分辨率海洋环流模型的模拟研究了孟加拉湾 (BoB) 和安达曼海 (AS) 半日正压和内部潮汐的能量学。正压 M 2 潮汐是该地区最大的潮汐成分，在 BoB 和 AS 中损失了约 65.5 GW 的能量。大部分正压能量（46.5 GW）通过浅海区域的底部摩擦耗散，例如海湾的头部和马尔塔班湾。由于正压潮汐与底部地形的相互作用，大约三分之一的正压 M 2 能量 (19.1 GW) 被转换为内部潮汐，并且大部分转换 (84%) 发生在安达曼-尼科巴 (AN) 海脊上。与早期研究的估计相反，我们的结果表明，BoB 和 AS 中这种内部潮汐能的很大一部分 (59%) 会在远离发电地点的地方消散。与 BoB 相比，发现整个 AS 的能量耗散率很大，这可能会导致该区域的垂直混合增强。此外，对模型域内转换的时间可变性的分析表明，半昼夜波段中的能量转换在春季 - 小溪周期中在 11 到 27 GW 之间变化。由于河流径流引起的分层的季节性变化显着改变了 BoB 和 AS 北部发电点的潮汐能转换。