Innovative Observational Global and Regional Ocean Water Mass, Circulation, and Mixing Analyses

• Main Author: Lavin, Paige D.
• Other Authors: Johnson, Gregory C.
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: Abyssal; Circulation; Global; Mixing; Regional; Water mass; Physical oceanography; Oceanography; Bering Sea; Okhotsk; Pacific; Aleutian Island; Alaska
• Online Access: http://hdl.handle.net/1773/47664

Thesis (Ph.D.)--University of Washington, 2021 This dissertation applies novel methodology to existing oceanographic datasets in order to gain new insights into the circulation and mixing of water masses at both regional and global scales. Given the boom of in-situ data from programs such as Argo over the last two decades, in addition to the rising prevalence and accessibility of novel methods such as machine learning, we hope to build on the foundational understanding of these processes obtained from analyses of previous, sparser datasets. We investigate the water mass properties, circulation, and inferred near-bottom mixing of the ocean from a mean state perspective. This allows us to use as many observations as possible in our analyses of these important features of the ocean and to get at the “baseline” behavior of the ocean. The first portion of this dissertation focuses on using conductivity-temperature-depth (CTD) and velocity measurements from Argo floats to assess the mean transport of the Alaskan Stream (AS). This current is a western boundary current at the north edge of the North Pacific subpolar gyre that flows west-southwestward along the south side of Alaska and the Aleutian Island Arc to strongly influence physical and biological processes downstream in the Sea of Okhotsk and the Bering Sea. Since the start of the Argo program, a sufficient number of Argo floats have sampled the AS such that we are now able to quantify the zonal evolution of this current by mapping Argo data to across-current transects at a number of locations along the current’s extent. Alongshore absolute geostrophic transports in the top 2000 dbar (obtained by combining mean absolute 1000-dbar velocities from float displacements with the geostrophic velocity fields) were found to generally increase to the west. Full-depth transports are estimated by fitting a barotropic and the first two baroclinic modes calculated from a climatology to the absolute geostrophic velocities in the upper 2000 dbar and applying the velocities ...