Simulation of diurnal variability in vertical density structure using a coupled model

B. Yadidya,A. D. Rao,Sachiko Mohanty

doi:10.1038/s41598-021-90426-w

B. Yadidya, A. D. Rao + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-90426-w

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Abstract

The changes in the physical properties of the ocean on a diurnal scale primarily occur in the surface mixed layer and the pycnocline. Price–Weller–Pinkel model, which modifies the surface mixed layer, and the internal wave model based on Garrett–Munk spectra that calculates the vertical displacements due to internal waves are coupled to simulate the diurnal variability in temperature and salinity, and thereby density profiles. The coupled model is used to simulate the hourly variations in density at RAMA buoy (15° N, 90° E), in the central Bay of Bengal, and at BD12 (10.5° N, 94° E), in the Andaman Sea. The simulations are validated with the in-situ observations from December 2013 to November 2014. The primary advantage of this model is that it could simulate spatial variability as well. An integrated model is also tested and validated by using the output of the 3D model to initialize the coupled model during January, April, July, and October. The 3D model can be used to initialize the coupled model at any given location within the model domain to simulate the diurnal variability of density. The simulations showed promising results which could be further used in simulating the acoustic fields and propagation losses which are crucial for Navy operations.

Highlights

The changes in the physical properties of the ocean on a diurnal scale primarily occur in the surface mixed layer and the pycnocline
In the Indian Ocean, Kumar and Balasubramanian[1] implemented IWAVE model based on Garrett–Munk modal spectrum
Kumar et al.[4] coupled the Price–Weller–Pinkel[5] (PWP) model and the internal wave (IW) model based on Garrett–Munk spectra[6]

Summary

Introduction

The changes in the physical properties of the ocean on a diurnal scale primarily occur in the surface mixed layer and the pycnocline. Price–Weller–Pinkel model, which modifies the surface mixed layer, and the internal wave model based on Garrett–Munk spectra that calculates the vertical displacements due to internal waves are coupled to simulate the diurnal variability in temperature and salinity, and thereby density profiles. In the Indian Ocean, Kumar and Balasubramanian[1] implemented IWAVE model based on Garrett–Munk modal spectrum They simulated the diurnal variations in temperature and salinity for two days off the west coast of India. The second case uses an integrated model, consisting of 3D MITgcm and coupled model when in-situ observations are not available We test both model set-ups in the central Bay of Bengal and the Andaman Sea. The maximum variations in the vertical profiles of density on a diurnal scale are mainly seen in the pycnocline region. Since the observations of meteorological variables at BD12 are not available, the surface heat, momentum, and salt fluxes are obtained from ERA510 reanalysis data

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