Modelling the Atlantic Water along its poleward pathway into and through the Arctic Ocean

• Author / Creator

  Fu, Chuanshuai

• The thermohaline intrusion of the warm and saline Atlantic Water (AW) into the Arctic Ocean, referred to as “Arctic Atlantification”, has significant implications and feedback on the {thermo}dynamics of the Arctic Ocean. The AW enters the Arctic Ocean through two gateways: Fram Strait and the Barents Sea Opening (BSO), and the relative strength of these two AW branches dominates the oceanic heat contribution to the Arctic Ocean. In conjunction with the measurements in key hydrographic sections, numerical ocean modelling provides us with a useful tool to characterize and corroborate the temporal and spatial variability of the AW branches. The simulations are carried out using the regional configuration the Arctic and North Hemispheric Atlantic (ANHA) of the ocean/sea-ice model NEMO running at 1/4° and 1/12° high resolutions. Online passive tracers from the model configurations are used to trace the pathways of the AW inflow in the Arctic Ocean.
  With the AW becoming more important to the dynamics of the Arctic Ocean, this study aims to examine its variability, transformation, and impacts, as well as ultimately track how it evolves. We first evaluate the interannual and seasonal variability of the AW thermohaline structure at these two gateways, then quantify the AW volume and heat transport on the interannual and seasonal timescales. We also compare long-term transport means with the available observations. While the heat in the Fram Strait Branch Water (FSBW) dissipates in a slower process through the mixing with the ambient cold water below the sea surface, the vast majority of the heat loss of the Barents Sea Branch Water (BSBW) takes place in the Barents Sea due to the sea surface cooling. In our study, we discover two strong Cold AW anomaly events along the rim of the eastern Eurasian Basin during 2013 and 2014, overturning our understanding that the AW is always warm and saline. The dominant contributor to the Cold AW formation is the intense sea surface cooling at the Barents Sea for two consecutive years. By releasing particles at the Barents Sea Opening and Fram Strait using an offline Lagrangian product Ariane, we find that the source of the Cold AW is primarily from the BSBW, and it also has some contributions from the FSBW. The Cold AW signals progress along the typical AW poleward pathway and eventually result in a heat content reduction in the AW layer of the eastern Arctic Basin.

• Subjects / Keywords

  • Atlantic Water Pathways
  • Arctic Ocean
  • Arctic Atlantification
  • Numerical Modelling

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-gadk-ny91

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.