Tutorial : the DEM Breakline and Differencing Analysis Tool—step-by-step workflows and procedures for effective gridded DEM analysis

Abstract

The DEM Breakline and Differencing Analysis Tool is the result of a multi-year research effort in the analysis of digital elevation models (DEMs) and the extraction of features associated with breaklines identified on the DEM by numerical analysis. Developed in the ENVI/IDL image processing application, the tool is designed to serve as an aid to research in the investigation of DEMs by taking advantage of local variation in the height. A set of specific workflow exercises is described as applied to a diverse set of four sample DEMs. These workflows instruct the user in applying the tool to extract and analyze features associated with terrain, vegetative canopy, and built structures. Optimal processing parameter choices, subject to user modification, are provided along with sufficient explanation to train the user in elevation model analysis through the creation of customized output overlays.

Increasing rate of 21st century volume loss of the Patagonian Icefields measured from proglacial river discharge

“…All studies, however, indicate rapid rates of volume loss in the land-or lake-terminating eastern margins of the SPI and NPI considered in this study, which exhibit some of the most rapid ablation rates (locally exceeding 10 m a −1 ) of any region on Earth Zemp and others, 2019). In addition, the two most recent studies considering multiple time period of elevation changes (Hugonnet and others, 2021;McDonnell and others, 2022) show an increase in the rate of ice loss over time for both the SPI and NPI, consistent with our findings.…”

“…6). McDonnell and others (2022) highlight how sub-sampling of elevation loss maps can lead to biases in regional mass balance estimates. They show that when comparing the same glaciers between 1979-2000 and 2000-2020, ice loss on the NPI has increased by a factor of 1.2 and ice loss on the SPI has increased by a factor of 2.4.…”