The Bay of Bengal, the eastern part of the northern Indian Ocean, experiences a reversal of monsoonal winds that control its surface and subsurface hydrological characteristics. Due to the limited number of studies, many aspects of the Bay of Bengal water column, particularly its deep hydrodynamic characteristics, are not thoroughly understood. For this purpose, oxygen isotopic compositions of water (δ¹⁸O), a potential tracer of oceanographic study, were measured at twelve discrete depths at eight locations in the central Bay of Bengal during the summer monsoon. The water columns were sampled to include surface (≤10 m), subsurface zone (25, depth of Deep Chlorophyll Maxima, 75, and 100 m), intermediate zone (150, 200, 300, and 500 m) and deep zone (1000, 1500, and 2000 m). Slopes of δ¹⁸O-salinity relationships at the surface and subsurface zones were similar. The δ¹⁸O and salinity showed an increasing southward trend at the surface, subsurface, and intermediate zones, which could be attributed to the influx of relatively saline and ¹⁸O enriched water from the Arabian Sea through Southwest Monsoon Current. The TS characteristics along with the negative slope of δ¹⁸O-salinity in the intermediate zone (−0.51 ± 0.14) indicated the presence of Indonesian Throughflow water in the Bay of Bengal. Temporal variation in δ¹⁸O and slope of δ¹⁸O-salinity relationship in the intermediate zone was also observed, possibly indicating variable contribution of Indonesian Throughflow water mass through time. The δ¹⁸O of the deeper water showed the signature of existence of North Atlantic Deep Water in the Bay. Mesoscale eddies, a frequent phenomenon in the Bay of Bengal, also seem to modulate the δ¹⁸O-salinity relationship in the basin.

北印度洋东部的孟加拉湾经历了季风逆转，控制了其地表和地下的水文特征。由于研究数量有限，孟加拉湾水体的许多方面，特别是其深部水动力特征，尚未完全了解。为此，在夏季季风期间，在孟加拉湾中部八个地点的十二个离散深度处测量了水的氧同位素组成 (δ ¹⁸ O)，这是海洋学研究的潜在示踪剂。采样的水体包括地表（≤10 m）、地下带（25，深叶绿素最大值的深度，75 和 100 m）、中间带（150、200、300 和 500 m）和深带（1000 、1500 和 2000 米）。δ ^{18 的}斜率地表和地下区域的 O 盐度关系相似。δ ¹⁸ O 和盐度在地表、次表层和中间带均呈向南增加的趋势，这可能是由于阿拉伯海通过西南季风流流入的相对咸水和富含¹⁸ O 的水。TS 特征以及中间带δ ¹⁸ O 盐度的负斜率(-0.51 ± 0.14) 表明孟加拉湾存在印度尼西亚通流水。时间变化中δ ¹⁸ O和δ的斜率¹⁸还观察到中间带中的 O 盐度关系，可能表明印度尼西亚通流水质量随时间变化的贡献。较深水的δ ¹⁸ O表明该湾存在北大西洋深水的特征。孟加拉湾常见的中尺度涡旋似乎也调节了盆地中的 δ ¹⁸ O-盐度关系。