Oceanographic Dynamics and Coastal Processes in the Indian Ocean

The Indian Ocean is characterised by a unique interplay of monsoon-driven circulation, western boundary currents, mesoscale eddies and coastal upwelling systems. Seasonal reversal of the South Asian monsoon governs large-scale flows such as the Somali Current and the East India Coastal Current, modulating heat and salt transport. Mesoscale features—including cyclonic and anticyclonic eddies—mediate exchanges between the open ocean and continental shelves, impacting nutrient supply and biological productivity. Coastal processes such as Ekman upwelling, topographically induced upwelling and wave‐driven coastal trapping shape regional ecosystems and fisheries. Intraseasonal perturbations, notably the Madden–Julian Oscillation, generate rapid sea‐level and mass‐transport variations, while interannual modes like the Indian Ocean Dipole and El Niño–Southern Oscillation drive basin-scale changes in stratification, sea surface temperature and chlorophyll distributions. The combination of these dynamical and thermodynamic processes has profound implications for regional climate modulation, coastal resource management and hazard risk, including storm surge and shoreline erosion in densely populated littoral zones.

Research from Nature Portfolio

Recent studies have revealed significant basin-scale barotropic sea-level variability associated with intraseasonal wind forcing. Evidence shows that rapid barotropic adjustments, linked to boreal winter Madden–Julian Oscillation events, contribute substantially to sea‐level budgets and propagate far more quickly than previously recognised baroclinic signals. Observational analyses of the eastern Arabian Sea demonstrate that freshwater influx from precipitation and river runoff modulates upper-ocean stratification, thereby controlling the intensity of coastal upwelling and influencing small pelagic fishery yields. Modelling investigations have further highlighted the role of the Andaman and Nicobar archipelago in shaping eddy generation along the western boundary of the Bay of Bengal. The presence of islands alters baroclinic and barotropic instabilities, leading to spatial variability in cyclonic and anticyclonic eddy frequency and consequent impacts on regional mixing and productivity.

Oceanographic Dynamics and Coastal Processes in the Indian Ocean publication trend

The graph below shows the total number of articles in oceanographic dynamics and coastal processes in the indian ocean across all publications each year (not limited to Nature Index journals).

Technical terms

Ekman upwelling: The uplift of deeper water toward the surface caused by wind‐driven cross-shore Ekman transport.

Mesoscale eddy: A coherent rotating water mass, 10–100 km in diameter, that redistributes heat, salt and nutrients in the upper ocean.

Barotropic process: Ocean dynamics involving a uniform vertical response of the entire water column to forcing.

Baroclinic process: Ocean dynamics governed by vertical density stratification and associated internal wave motions.

Stratification: The vertical layering of water masses due to density differences arising from temperature or salinity gradients, which influences mixing.

Madden–Julian Oscillation (MJO): A large-scale eastward-propagating atmospheric disturbance with a 30–60 day period that affects tropical convection and winds.

Indian Ocean Dipole (IOD): A coupled ocean–atmosphere mode characterised by anomalous east–west sea surface temperature gradients across the equatorial Indian Ocean.

References

1. Basin-wide sea level coherency in the tropical Indian Ocean driven by Madden–Julian Oscillation. Nature Communications (2019).
2. Observational evidence of stratification control of upwelling and pelagic fishery in the eastern Arabian Sea. Scientific Reports (2021).
3. Role of Andaman and Nicobar Islands in eddy formation along western boundary of the Bay of Bengal. Scientific Reports (2019).
4. Reviews and syntheses: Physical and biogeochemical processes associated with upwelling in the Indian Ocean. Biogeosciences (2021).
5. Thermohaline Structures and Heat/Freshwater Transports of Mesoscale Eddies in the Bay of Bengal Observed by Argo and Satellite Data. Remote Sensing (2019).