Methods of Ensemble Data Assimilation on Adaptive Moving Meshes ...

• Main Author: Guider, Colin Thomas
• Format: Thesis
• Language: English
• Published: The University of North Carolina at Chapel Hill University Libraries 2019
• Subjects: Sea ice
• Online Access: https://dx.doi.org/10.17615/bwc6-3891; https://cdr.lib.unc.edu/concern/dissertations/1831cq45m

Numerical models solved on adaptive moving meshes have become increasingly prevalent in recent years. In particular, neXtSIM is a 2D model of sea-ice that is numerically solved on a Lagrangian mesh that does not conserve the number of mesh points. In this dissertation, we present two novel approaches to the formulation of ensemble data assimilation for models with this underlying computational structure. Specifically, we map ensemble members onto a common reference mesh, where the Ensemble Kalman Filter (EnKF) can be performed. Numerical experiments are carried out using 1D prototypical models: Burgers and Kuramoto-Sivashinsky equations, with both Eulerian and Lagrangian synthetic observations assimilated. One of the approaches is very effective, while the other is significantly less so. We also present a novel approach in the formulation of the Local Ensemble Transform Kalman Filter (LETKF) on a conservative moving mesh model. This is also achieved by mapping the ensemble members onto a common reference ...