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Activity Number: 90 - Invited EPoster Session
Type: Invited
Date/Time: Sunday, July 28, 2019 : 8:30 PM to 10:30 PM
Sponsor: ASA
Abstract #307433
Title: Estimating Heat Diffusion in the Firn of the Greenland Ice Sheet
Author(s): Darren Gemoets and Dylan Griffith and Snehalata Huzurbazar* and Neil Humphrey
Companies: West Virginia University and West Virginia University and West Virginia University and University of Wyoming
Keywords: diffusion coefficient; pde; parameter cascading; Bayesian hierarchical models; spatiotemporal data; glaciology; uncertainty quantification
Abstract:

Estimating the rate at which heat diffuses in ice sheets is an important problem; such diffusion coefficients are assumed ‘constants’ in more complicated climate models. Using temperature data collected over several months from theremistors placed along the depths of boreholes in the firn of the Greenland ice sheet, we use methods from the statistics literature, functional data analysis via parameter cascading (Xun et al., 2013 JASA) and Bayesian hierarchical modeling (Wikle, 2003, Ecology among others), to compare methodological details and estimates of the diffusion coefficient. In the latter, we investigate the performance of different discretizations for solving the heat equation pde: Forward Euler, Backward Euler and Crank-Nicholson, as Forward Euler is potentially unstable, while the other two are unconditionally stable schemes. Specifically, we examine the effect on the posterior distributions of the diffusion coefficient and the variances of the observation and process errors. The FDA code runs much faster than the BHM, but provides less information. Our comparisons are motivated by recommendations that would be useful to our glaciologist collaborator.


Authors who are presenting talks have a * after their name.

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