EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seasonal contribution to the spice generation in subtropical south Indian salinity maxima

Madhu Kaundal1, Jithendra Nadimpalli1,2, and Mihir Dash1
Madhu Kaundal et al.
  • 1Indian Institute of Technology Kharagpur, Centre for Oceans, Rivers, Atmosphere and Land Sciences (CORAL), Kharagpur, India (
  • 2Indian Institute of Technology Madras, Aerospace Eng., India (

Regions of salinity maxima (Smax) in the world oceans experience spiciness changes which in-turn subduct and advect towards equator along the shallow meridional overturning cell. Advection results in stabilizing vertical salinity gradient (salinity increasing with depth) along westward and equatorward edges of Smax region whereas eastward and poleward edges holds destabilizing vertical salinity gradient with maximum salinity at surface (salinity decreasing with depth). Based on this contrast vertical salinity gradient, subtropical south Indian Ocean salinity maxima region is divided into two boxes along 30ºS. Seasonal evolultion of spiciness with respect to atmospheric and oceanic forcings, are investigated by using high frequency (3-day), high resolution (0.25º) ECCO (Estimating the Circulation and Climate of the Ocean) estimate. It is observed that in both these boxes, spice generation mechanisms are different. During austral winter, 25-sigma isopycnal outcrops to the north of 30S (northern box), along which the Temperature/Salinity changes subduct and hence spiciness anomalies are formed below the mixed layer. However, destabilization of vertical salinity gradient to the south of 30S (southern box), concomitant with weak stratification results in convective mixing at the mixed layer base and hence the spiciness changes penetrate the main thermocline. Seasonal mixed layer heat and salt budget analysis show that the surface heat and freshwater fluxes are the main forcings controlling monthly evolution of spiciness in the northern box, whereas in the southern box entrainment and meridional advection terms are mainly contributing for the spiciness changes.

How to cite: Kaundal, M., Nadimpalli, J., and Dash, M.: Seasonal contribution to the spice generation in subtropical south Indian salinity maxima, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1537,, 2021.


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