Prajwal Prakashrao Jadhav

I am a PhD student in Physical Oceanography. My research focuses on modelling the impact of upper-ocean turbulence in the tropical ocean. My project is part of Collaborative Research Centre TRR 181: Energy Transfers in the Atmosphere and Ocean, funded by the German Research Foundation (DFG).

At the equator, vertical shear between the westward surface equatorial current (SEC) and the eastward equatorial undercurrent (EUC) keeps the upper ocean in a state of marginal instability. Under nighttime atmospheric forcing, such as wind stress, instabilities can develop in the shear layer and lead to a phenomenon called deep cycle turbulence (DCT). However, during the daytime, the formation of a stratified Diurnal Warm Layer (DWL) close to the ocean surface limits the penetration of atmospheric forcing in the ocean, thereby damping DCT. DCT modulates the upper-ocean heat content, which directly influences sea surface temperature (SST) and thereby air–sea energy exchange. This motivates accurate representation of DCT in numerical models.

Currently, I am exploring various one-dimensional statistical turbulence models within GOTM to identify the simplest yet sufficiently accurate model for representing DCT. The figure shows a simulation of the upper equatorial ocean over a three-day period using the k–ε model. Turbulence extends to greater depths during nighttime and is suppressed during the daytime due to the formation of the DWL at the ocean surface.

In the future, based on high-resolution coupled ocean–atmosphere simulations with ICON, I plan to examine how DCT is influenced by the diurnal cycle of atmospheric fluxes and interactions with Tropical Instability Waves (TIWs), as well as how these oceanic processes feed back to the atmosphere.