Near-Surface Oceanic Kinetic Energy Distributions From Drifter Observations and Numerical Models

The geographical variability, frequency content, and vertical structure of near-surface oceanic kinetic energy (KE) are important for air-sea interaction, marine ecosystems, operational oceanography, pollutant tracking, and interpreting remotely sensed velocity measurements. Here, KE in high-resolution global simulations (HYbrid Coordinate Ocean Model; HYCOM, and Massachusetts Institute of Technology general circulation model; MITgcm), at the sea surface (0 m) and at 15 m, are compared with KE from undrogued and drogued surface drifters, respectively. Global maps and zonal averages are computed for low-frequency

Wind and tidal response of a semi-enclosed bay, Bahía Concepción, Baja California

In this dissertation, I report on a field study that took place in Bahía Concepción (BC), Baja California, and related modeling. The principal goal of this thesis is to extract the winter wind driven response of the bay and compare it with recently developed theoretical models. The first results of this thesis are nevertheless theoretical and derived from an extension of previous models to the time-dependent case. This extension allows to quantify the spin up time scale of the steady response. A damped resonant response is predicted at the inertial frequency. This is a result of importance for BC, which is located at 26.7⁰N where the diurnal sea breeze oscillates at a near- inertial frequency. This theoretical development guides the analysis of observations inside BC. This analysis consists first in understanding the sub-inertial response. The along-bay sea level set-up predicted by theory is observed. Wind driven currents proved to be more difficult to extract and the comparison with theory is partially successful. Downwind currents are present over shallow areas and cross-wind currents are sometimes observed. An analysis of the dynamics suggests the importance of stratification and nonlinearities which are ignored in the theoretical models. In the diurnal/inertial band, the response is similar to the theoretical predictions developed in the early part of this thesis. Two layer-like currents are present and rotate in the clockwise direction with time. When vertical stratification is present, baroclinic effects are shown to contribute to the dynamics. Finally, I extract the current and sea level response to sea level fluctuations at the mouth of BC. The sea level at the closed end of BC follows a theoretical model with two interconnected basins. There is a resonant response near 5 cycles per day, which is identified as the quarter wavelength of the bay. Along-bay currents are consistent with theoretical predictions. This is not the case for across-bay current

Wind and tidal response of a semi-enclosed bay, Bahía Concepción, Baja California

In this dissertation, I report on a field study that took place in Bahía Concepción (BC), Baja California, and related modeling. The principal goal of this thesis is to extract the winter wind driven response of the bay and compare it with recently developed theoretical models. The first results of this thesis are nevertheless theoretical and derived from an extension of previous models to the time-dependent case. This extension allows to quantify the spin up time scale of the steady response. A damped resonant response is predicted at the inertial frequency. This is a result of importance for BC, which is located at 26.7⁰N where the diurnal sea breeze oscillates at a near- inertial frequency. This theoretical development guides the analysis of observations inside BC. This analysis consists first in understanding the sub-inertial response. The along-bay sea level set-up predicted by theory is observed. Wind driven currents proved to be more difficult to extract and the comparison with theory is partially successful. Downwind currents are present over shallow areas and cross-wind currents are sometimes observed. An analysis of the dynamics suggests the importance of stratification and nonlinearities which are ignored in the theoretical models. In the diurnal/inertial band, the response is similar to the theoretical predictions developed in the early part of this thesis. Two layer-like currents are present and rotate in the clockwise direction with time. When vertical stratification is present, baroclinic effects are shown to contribute to the dynamics. Finally, I extract the current and sea level response to sea level fluctuations at the mouth of BC. The sea level at the closed end of BC follows a theoretical model with two interconnected basins. There is a resonant response near 5 cycles per day, which is identified as the quarter wavelength of the bay. Along-bay currents are consistent with theoretical predictions. This is not the case for across-bay current