Simulation of the Laptev Sea shelf dynamics with focus on the Lena Delta region

• Main Author: Fofonova, Vera
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2014
• Subjects: Arctic; Laptev Sea; Climate change; laptev; lena delta; lena river
• Online Access: http://nbn-resolving.org/urn:nbn:de:gbv:579-opus-1004756

The polar shelf zones are highly dynamic and diverse systems. They form a border between warm and fresh water of continental drain and the cold currents of the northern seas. The Lena River is one of the largest rivers in the Arctic, with the largest delta. The south-eastern part of the Laptev Sea, which includes the Lena Delta region, is the place where substantial changes in ocean circulation and ecosystem may happen in changing climate. Exploring processes there, which may serve as an indicator of climate change, acquire a special importance. The Lena freshwater plume propagation dominates many aspects of dynamics in the Laptev Sea shelf. However, the direct measurements are by far insufficient, calling for a modeling approach which would enable one to estimate the impact of different factors on the circulation dynamics and would lay the foundation for further ecosystem modeling. The complexity of the region’s geometry and insufficient data make modeling of ocean circulation in the Lena Delta vicinity a challenging technical task not solved in the necessary detail previously. The quantitative effect of various factors (tides, winds, hear exchange with the atmosphere) on the freshwater plume propagation also has not been fully explored. The main goal of this thesis is the analysis of the Lena River freshwater plume dynamics in the summer season on the basis of a full baroclinic numerical model of the Laptev Sea shelf with focus on the Lena Delta region. The setup is based on FVCOM (The Unstructured Grid Finite Volume Coastal/Community Ocean Model). The thesis contains a detailed description of the model setup, including the generation of an unstructured mesh, analysis of barotropic and baroclinic dynamics in the region of interest, the description of new approaches for the model elaboration and visualization of simulation results and a comparison of the impact of different atmospheric forcing products on the simulated dynamics. Special attention is paid to the Lena River hydrology regime in the basin outlet, ...