On the Dynamics of the Ross Gyre: Relative Importance of Wind, Buoyancy, Eddies, and Antarctic Circumpolar Current

• Other Authors: Wang, Yang (author), Chassignet, Eric P. (professor co-directing dissertation), Speer, Kevin G. (Kevin George) (professor co-directing dissertation), Bourassa, Mark Allan (university representative), Dewar, William K. (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Scientific Computing (degree granting department)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Florida State University 2022
• Subjects: Oceanography; Antarctic; The Antarctic; Ross Sea; Antarc*
• Online Access: https://diginole.lib.fsu.edu/islandora/object/fsu%3A887420/datastream/TN/view/On%20the%20Dynamics%20of%20the%20Ross%20Gyre.jpg

Formation of cold, dense waters south of the Antarctic Circumpolar Current (ACC) is one of the main drivers of the global overturning circulation, with major implications on the earth's climate. A key region where the densest waters on earth are formed is the Ross Sea which is separated from the ACC by the Ross Gyre. The strength and variability of the Ross Gyre circulation impact the formation and export of dense water, and it is therefore important to understand its circulation and dynamics. Observations in the Ross Gyre are limited because of its remote location and the severe weather conditions. Furthermore, the ice cover limits the application of remote sensing techniques. Quantitative estimates of the gyre's strength are difficult to obtain from hydrographic observations alone due to the limited sampling and the relatively weak stratification. In this dissertation, we use a combination of observations and modeling studies to a) provide an estimate of the strength and variability of the Ross Gyre transport and b) investigate the relative contributions of the wind and buoyancy forcing, eddies, and the presence of ACC to the Ross Gyre circulation. We find that the mean transport of the Ross Gyre can be as high as ~45 Sv, about twice of the typical estimate ~20 Sv reported in the literature. Sensitivity experiments to wind and buoyancy forcing, nonlinear terms, and the ACC were performed with a regional configuration of the Hybrid Coordinate Ocean Model (HYCOM). The numerical experiments show that the Ross Gyre, and its variability, are primarily wind-driven. The ACC is responsible for part of the recirculation. Buoyancy and nonlinearity/eddy do not appear to play a major role in the gyre dynamics. A Dissertation submitted to the Department of Scientific Computing in partial fulfillment of the requirements for the degree of Doctor of Philosophy. October 31, 2022. Dynamics, Gyre transport, Gyre Variablitity, Numerical modeling, Ross Gyre, Wind stress Includes bibliographical references. Eric ...