SMAST Seminar - DEOS - "Internal wave trapping in curved ocean fronts" By: Patibandla B Ramana
When: Tuesday,
October 29, 2024
12:30 PM
-
1:30 PM
Where: > See description for location
Description: Department of Estuarine and Ocean Sciences
"Internal wave trapping in curved ocean fronts"
Patibandla B Ramana, Postdoctoral Fellow Tandon Lab
University of Massachusetts Dartmouth
Please note, due to the University wide mental health day 10/30 the seminar will take place on Tuesday 10/29.
Tuesday, October 29, 2024
12:30 - 1:30 pm
SMAST E 101-102 and via Zoom
Abstract:
The action of wind over the stratified ocean generates mesoscale flows (currents, eddies, etc.) balanced by the Earth's rotation and, in addition, waves oscillating with near-Coriolis frequencies (termed 'near-inertial waves (NIWs)'). Due to their large vertical shear, NIWs are one of the primary mechanisms responsible for upper ocean mixing. Furthermore, NIWs are modulated by the presence of strong sub/mesoscale flows and corresponding fronts, altering their propagation and dissipation characteristics. The local rotation rate (vorticity) of such balanced flows modifies the effective frequency of NIWs, expelling them from the positive vorticity (cyclonic) regions and trapping them in negative vorticity (anticyclonic) regions. Trapped NIWs propagate to the ocean interior, as their vertical wavenumber reduces, and deposit their energy at a critical depth. Such trapping of NIW energy at a critical depth can affect internal mixing, transport of nutrients and bottom ventilation. Recent works show that baroclinic effects due to the presence of straight density fronts and the curvature of fronts can further enhance the NIW trapping region. In the current work, we study the NIW trapping characteristics for a wide range of frontal curvatures. In doing so, we model the curved front to be represented by a portion of a CLM vortex, which contains a shield of opposite vorticity surrounding the vortex core. Using ray-tracing and numerical methods, we show that frontal curvature can: (a) increase the critical depth and horizontal extents of the trapping region, (b) reduce NIW activity in the anticyclonic vortex core and enhance it in the cyclonic shield surrounding the core, (c) lead to NIW trapping in the anticyclonic shield surrounding the cyclonic core, and (d) increase the available band of NIW frequencies that can get trapped. These results generalize the effect of various factors in NIW trapping and have implications for ocean mixing.
***********************************************************
For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu
"Internal wave trapping in curved ocean fronts"
Patibandla B Ramana, Postdoctoral Fellow Tandon Lab
University of Massachusetts Dartmouth
Please note, due to the University wide mental health day 10/30 the seminar will take place on Tuesday 10/29.
Tuesday, October 29, 2024
12:30 - 1:30 pm
SMAST E 101-102 and via Zoom
Abstract:
The action of wind over the stratified ocean generates mesoscale flows (currents, eddies, etc.) balanced by the Earth's rotation and, in addition, waves oscillating with near-Coriolis frequencies (termed 'near-inertial waves (NIWs)'). Due to their large vertical shear, NIWs are one of the primary mechanisms responsible for upper ocean mixing. Furthermore, NIWs are modulated by the presence of strong sub/mesoscale flows and corresponding fronts, altering their propagation and dissipation characteristics. The local rotation rate (vorticity) of such balanced flows modifies the effective frequency of NIWs, expelling them from the positive vorticity (cyclonic) regions and trapping them in negative vorticity (anticyclonic) regions. Trapped NIWs propagate to the ocean interior, as their vertical wavenumber reduces, and deposit their energy at a critical depth. Such trapping of NIW energy at a critical depth can affect internal mixing, transport of nutrients and bottom ventilation. Recent works show that baroclinic effects due to the presence of straight density fronts and the curvature of fronts can further enhance the NIW trapping region. In the current work, we study the NIW trapping characteristics for a wide range of frontal curvatures. In doing so, we model the curved front to be represented by a portion of a CLM vortex, which contains a shield of opposite vorticity surrounding the vortex core. Using ray-tracing and numerical methods, we show that frontal curvature can: (a) increase the critical depth and horizontal extents of the trapping region, (b) reduce NIW activity in the anticyclonic vortex core and enhance it in the cyclonic shield surrounding the core, (c) lead to NIW trapping in the anticyclonic shield surrounding the cyclonic core, and (d) increase the available band of NIW frequencies that can get trapped. These results generalize the effect of various factors in NIW trapping and have implications for ocean mixing.
***********************************************************
For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu
Contact: > See Description for contact information
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