An investigation of dynamic surface elevation and volume changes of Tasman Glacier using multi-temporal ASTER derived digital elevation models

Abstract

The Tasman Glacier is the largest ice mass in New Zealand and has been a research focus since the 19th century. Since the dramatic frontal changes and retreat associated with the development of the Tasman Lake, a new influx of interest in characterising different elements of glacial change has evolved with the advent of new monitoring techniques. However, studies to date documenting glacial surface elevation and volume changes using remote sensing data and photogrammetric techniques have typically been carried out at a low temporal resolution. To address this, the aim of this research is to assess annual dynamic surface elevation and volume changes of the Tasman Glacier using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data over a 13-year period from 2000 to 2013. The novel multi epoch triangulation method implemented allows detailed changes to be investigated without compromising spatial or temporal resolution. The resulting multi temporal DEMs, with annually matching bathymetric data, provides a new and spatially comprehensive annual representation of the dynamic changes in elevation and volume across the Tasman Glacier. The average rate of glacier wide rate elevation loss over the study period was −1.79 ± 0.38 m a-1 but the magnitude of the changes on an annual scale varied considerably. The volume of ice loss was estimated to be −10.18 x 108 m3 between 2000 and 2013. The major source of ice loss over the entire period was controlled primary by the expansion of Tasman Lake, which made up 47% of the total volume of ice loss. The volume change of the Tasman Lake over 10 of the 12 observation years was 0.23 x 108 m3 yr-1. During 2007 and 2008 rates increased to 0.99 x 108 m3 yr-1 and 1.56 x 108 m3 yr-1, respectively. The incorporation of flow field data enabled a robust relationship between tributary inflow velocities and elevation change to be established along the Tasman Glacier using linear regression (R2 = 0.82). The identification of physical processes controlling glacier dynamics at short temporal scales demonstrated that the Tasman Glacier can respond rapidly to changes in ice influx, which has important implications when assessing longer term glacier dynamics.