Date of Award

2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Ocean Science and Engineering

Committee Chair

Maarten C. Buijsman

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dmitri A. Netchaev

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Stephan D. Howden

Committee Member 3 School

Ocean Science and Engineering

Committee Member 4

Alexander E. Yankovsky

Committee Member 5

Jay F. Shriver

Abstract

This dissertation focuses on semidiurnal (D2) surface and internal tides. Chapter 2 investigates the transition of M2 barotropic Kelvin waves into Hybrid Kelvin-Edge (HKE) waves and the associated generation of internal tides at widening shelves using theory and a realistic global baroclinic Hybrid Coordinate Ocean Model (HYCOM) simulation. To understand the effect of complex, realistic bathymetry on the HKE wave transition, we perform quasi-realistic barotropic HYCOM simulations of the Celtic Sea/Bay of Biscay shelf areas. We conclude that the HKE wave transition is most likely masked by the effects of complex bathymetry and offshelf baroclinic fluxes cannot be exclusively attributed to the HKE wave transition.

In Chapter 3, we study the seasonal variability of total (stationary and non-stationary) D2 internal tide and the phase-locked (stationary) M2 internal tide sea surface height (SSH) using global HYCOM simulations and altimeter datasets. The internal tides generated in the coastal regions of Georges Bank and the Arabian Sea feature the strongest seasonal variability. The amplitude of the seasonal cycle and the seasonal arrival times (phase) of the semidiurnal internal tides in the HYCOM simulation agree with these observed in the altimetry data. However, the variance (amplitude) of M2 steric sea surface height (SSSH) in the HYCOM simulation is about 70% (20%) larger than in the altimeter observations. Even after applying a correction for bottom pressure, the HYCOM SSSH remains larger than the altimetry M2 variance.

Chapter 4 compares the seasonal variability observed in the D2 SSSH variance with D2 internal tide energetics using global HYCOM simulations and an altimeter dataset. The seasonal trends of monthly SSSH variance and energetics are in phase in Georges Bank and the Arabian Sea. However, outside these hotspots, the seasonal variability in D2 energetics is out of phase with D2 SSSH variance. While the seasonal variability in D2 energy is driven by seasonal changes in barotropic to baroclinic conversion at topography, D2 SSSH variance is also modulated by seasonal changes in surface stratification. Hence, one should be careful in interpreting the temporal variability in internal tide SSH as the "true" internal tide variability, which is better determined from energetics.

ORCID ID

0000-0001-5132-0264

Download

  Contact Author

Included in

Oceanography Commons

Share

COinS