Analysis and modeling of the distribution of tracers of glacial melt in the Southern Ocean with focus on the Southeast Pacific sector

• Main Author: Nakayama, Yoshihiro
• Other Authors: Lemke, Peter, Hellmer, Hartmut, Kanzow, Torsten
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2015
• Subjects: Antarctica; Amundsen Sea; Pine Island Glacier; ice shelf-ocean interaction; glacial melt water; Ross Sea; 530; 530 Physics; ddc:530; Antarctic; Southern Ocean; West Antarctic Ice Sheet; Bellingshausen Sea; Pacific; Simu; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Pine Island; Sea ice
• Online Access: https://media.suub.uni-bremen.de/handle/elib/804; https://nbn-resolving.org/urn:nbn:de:gbv:46-00104246-16

In the Pacific sector of the Southern Ocean, the ice shelves and glaciers of the West Antarctic Ice Sheet (WAIS) are rapidly thinning, especially in the Amundsen Sea (AS) and Bellingshausen Sea (BS). The high basal melting of these relative small ice shelves is caused by warm Circum- polar Deep Water (CDW) that, based on observations, mainly intrudes via submarine glacial troughs located at the continental shelf break. When CDW reaches the grounding line of the fringing glaciers, strong basal melting supports a buoyant melt water plume. As the glacial melt becomes part of the shelf circulation, it may cause a freshening of the shelf water locally as well as remotely in the Ross Sea (RS). In the RS, on the other hand, shelf water salinity has declined by 0.03 per decade over the past 50 years. Thus, the objective of this doctoral thesis is to simu- late the spreading of glacial melt water using the Finite-Element Sea-ice/ice-shelf/Ocean Model (FESOM) and investigate whether the ice shelf melting in the AS is one of the main reasons for the observed shelf water freshening in the RS. However, there are two main difficulties for the simulation of the spreading of glacial melt water: (1) the number of observations on the Amundsen Sea continental shelf and thus our un- derstanding of CDW intrusions, ice shelf basal melting, and spreading of glacial melt water is limited and (2) none of the high-resolution global models resolving all small ice shelves around Antarctica is able to simulate CDW intrusions realistically. Thus, in this doctoral study the hy- drographic data of the cruise ANTXXVI/3 from the eastern AS continental shelf was analyzed, focusing on intrusions of CDW, basal melting of Pine Island Ice Shelf (PIIS), and spreading of glacial melt water. The data analysis was followed by several model sensitivity experiments using FESOM. They revealed that the model configuration such as horizontal resolution and atmospheric forcing is important for the reproduction of CDW intrusions. With these modifications, FESOM ...