דוקטורנטים מספרים - Subhajit Kar
Energy exchanges between wind-forced waves and the ocean’s circulation
Subhajit Kar (Ph.D. candidate)
Supervisor: Dr. Roy Barkan
Hi! I am Subhajit Kar. I completed my undergraduate and post-graduate studies in Mechanical Engineering in India before coming to study in Israel. In 2020, I registered as a PhD student in the Porter School of the Environment and Earth Sciences. My research is focused on 'Physical Oceanography' under the supervision of Dr. Roy Barkan.
The ocean's circulation is continuously forced by atmospheric wind, tides caused by the moon, and thermal heating by the sun. Surprisingly, the ocean is in a quasi-steady state, which means no sudden abrupt changes. Otherwise, we would see catastrophic events such as cyclones and tsunami daily, making this planet uninhabitable. Thus, the quasi-steady state of a continuously forced ocean is puzzling to many scientists working in oceanography. This state can only be achieved if the energy of the forcing is dissipated at a small scale (scale of a centimeter). More specifically, the energy must be dissipated at the same rate as the forcing that supplies it. However, Earth's rotation causes the forcing energy to be kept at a large scale (typical scale of 100km) where it cannot be dissipated or removed. Thus, eventually, all the energy will accumulate at these scales in time, occasionally leading to a sudden burst, for example, in a volcanic eruption. However, we rarely see such events in the ocean. During my PhD studies, I will focus on this energy transfer from this large scale of the ocean (forcing scale) to the small scale. One of the prospective mechanisms proposed in the scientific community is the interaction of atmospheric wind-forced waves (also called near-inertial waves) generated near the ocean's surface (see figure below) and large-scale circulation. However, there is no clear mechanistic understanding of their interaction processes. During my PhD, I will try to understand the mechanism of such interactions, which leads the energy to cascade from large to small scales.
