The impact of northern Indian Ocean rivers on the Bay of Bengal using NEMO global ocean model

• Published in: Acta oceanologica Sinica Vol. 39; no. 3; pp. 45 - 55
• Main Authors: Srivastava, Atul, Gera, Anitha, Momin, Imran M., Mitra, Ashis Kumar, Gupta, Ankur
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Society of Oceanography 01-03-2020; Springer Nature B.V; National Centre for Medium Range Weather Forecasting, Noida 201309, India; Jaypee University Anoopshahr, Bulandshahr 203309, India%National Centre for Medium Range Weather Forecasting, Noida 201309, India
• Subjects: Brunt-Vaisala frequency; Climatology; Coastal currents; Earth and Environmental Science; Earth Sciences; Ecology; Engineering Fluid Dynamics; Environment and Ocean-Atmosphere Interaction in the Indian Ocean; Environmental Chemistry; Hydrography; Marine & Freshwater Sciences; Mixed layer; Mixed layer depth; Monsoons; Ocean circulation; Ocean models; Oceanography; Oceans; River discharge; River flow; River runoff; River water; Rivers; Runoff; Salinity; Salinity effects; Sea surface; Sea surface temperature; Seasons; Seawater; Stratification; Summer monsoon; Surface cooling; Surface runoff; Surface salinity; Surface temperature; Vertical shear; Water depth; Wind; Indian Ocean; Bay of Bengal; salinity; mixed layer depth; stratification; Bay of Bengal; sea surface temperature
• ISSN: 0253-505X; 1869-1099
• DOI: 10.1007/s13131-020-1537-9

The effect of river runoff over the northern Indian Ocean (NIO) especially over the Bay of Bengal (BoB) has been studied using global Nucleus for European Modelling of the Ocean (NEMO). Two sensitivity experiments, with and without river runoff are conducted and the influence of river runoff on the Indian Ocean hydrography, stratification and circulation features are studied. It is found that due to river runoff surface salinity over the northern BoB decreases by more than 5 and the East India Coastal Current strengthens by 2 cm/s during post monsoon season. The fresh river water reaches up to 15°N in the BoB and is the main cause for low salinity there. Sea surface temperature in the northwestern BoB increases by more than 0.2°C due to the river runoff in summer monsoon while surface cooling upto 0.2°C is seen in north-west part of BoB in winter season. The seasonal mixed layer depth in the region is found to be dependent on river runoff. The effect of vertical shear and Brunt Vaisala frequency on stratification is also examined. The ocean water becomes highly stratified up to 3 035 m due to the river runoff. It is found that the energy required for mixing is high in the northern and coastal BoB.