Sagar Bora

Name:              Sagar Bora (ESSReS PhD student)
Institute:          Alfred Wegener Intitute
Department:     Climate Science Division
Phone:             +49-(0)471-4831-1880
Web link:         AWI Research: Paleoclimate Dynamics

PhD-project title: Wave adjustment in a Finite Element Ocean Model

Wave processes represent an obvious way of transferring variability from one part of the ocean to the other. North Atlantic Ocean acts as a source of numerous perturbations in the form of strong convection or ice melting events. These events strongly perturb the composition of water masses, thus isopycnals, and these perturbations spread over the entire ocean. Pure advection aside, wave processes represents a particular route.

Finite Element Ocean Model is used to answer particular questions related to the role of bathymetry and coastlines, the role of dissipation on shaping the signals, and the sensitivity of the wave signal to the frequency of the perturbation. In the framework of a reduced gravity model, an elevated sea surface height (SSH) represents isopycnal displacement at the thermocline depth in the ocean.

Numerical modeling of Rossby waves is straightforward, because they are not localized and they have long wavelength and time period. However, the amplitude of Kelvin waves decreases exponentially from the coast. Hence, modeling them with traditional models with structured mesh is difficult. The model used here, Finite Element Ocean Model (FEOM) is one of the ocean general circulation models (OGCM). However, it differs from the other models in that its discretization is based on unstructured triangular meshes on the surface and prismatic volume elements in the volume. This variable resolution helps us resolve the localized Kelvin waves.


Start of doctoral thesis: 01.10.2008 | Defence: 25.03.2013

Thesis Committee:

Supervisor: Prof. Dr. G. Lohmann (AWI, Bremen University)

Co-Supervisor: Dr. S. Danilov (AWI)

Further members: Dr. M. Losch (AWI), Dr. Vlamidir Ivchenko (AWI, Nat. Oceanography Center/UK)


Sagar Bora, S. Danilov, and Gerrit Lohmann, Role of coastlines, dissipation and frequency of perturbation on internal wave propagation examined in a Finite Element Ocean Model, AGU Fall Meeting 2009, 14 -18 December 2009. (Poster) (PDF)