| Summary: | Hydrography and nutrient dynamics of the meridional sections along the 67 o E line in the western Indian Ocean were investigated during the neutral IOD events of 2017-2019 periods. Vertical distribution of temperature, salinity, and dissolved oxygen along the meridional section showed the presence of various water mass in the Indian Ocean: the Arabian Sea Surface Water (ASSW), the Red Sea Overflow Water(RSOW), the Indonesian Intermediate Water(IIW), the Subantarctic Mode Water(SAMW), the Subtropical Underwater(STUM), the Antarctic Intermediate Water(AAIW), the Indian Deep Water(IDW), and the Circumpolar Deep Water(CDW). The relative abundance of silicate over nitrate+nitrite (Si*) showed negative values at the depth of 750 m (27 o S), an indication of the northward intrusion of SAMW, and were observed in the shallow depth toward the north(~10 o S). We estimated nutrient concentration of each water type in the region and described the horizontal and vertical nutrient supplies into the surface layer.
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