Paper Info
Title
On the Automated Mapping of Snow Cover on Glaciers and Calculation of Snow Line Altitudes from Multi-Temporal Landsat Data.
Abstract
Mapping snow cover (SC) on glaciers at the end of the ablation period provides a possibility to rapidly obtain a proxy for their equilibrium line altitude (ELA) which in turn is a metric for the mass balance. Satellite determination of glacier snow cover, derived over large regions, can reveal its spatial variability and temporal trends. Accordingly, snow mapping on glaciers has been widely applied using several satellite sensors. However, as glacier ice originates from compressed snow, both have very similar spectral properties and standard methods to map snow struggle to distinguish snow on glaciers. Hence, most studies applied manual delineation of snow extent on glaciers. Here we present an automated tool, named ASMAG' (automated snow mapping on glaciers), to map SC on glaciers and derive the related snow line altitude (SLA) for individual glaciers using multi-temporal Landsat satellite imagery and a digital elevation model (DEM). The method has been developed using the example of the otztal Alps, where an evaluation of the method is possible using field-based observations of the annual equilibrium line altitude (ELA) and the accumulation area ratio (AAR) measured for three glaciers for more than 30 years. The tool automatically selects a threshold to map snow on glaciers and robustly calculates the SLA based on the frequency distribution of elevation bins with more than 50% SC. The accuracy of the SC mapping was about 90% and the SLA was determined successfully in 80% of all cases with a mean uncertainty of +/- 19 m. When cloud-free scenes close to the date of the highest snowline are available, a good to very good agreement of SC ratios (SCR)/SLA with field data of AAR/ELA are obtained, otherwise values are systematically higher/lower as useful images were often acquired too early in the summer season. However, glacier specific differences are still well captured. Snow mapping on glaciers is impeded by clouds and their shadows or when fresh snow is covering the glaciers, so that more frequent image acquisitions (as now provided by Sentinel-2) would improve results.
Year
DOI
Venue
2019
10.3390/rs11121410
REMOTE SENSING
Keywords
Field
DocType
Landsat,snow mapping,glacier,snow-covered area,mass balance,snow line altitude,equilibrium line altitude,multi-temporal analysis,digital elevation model
Glacier,Remote sensing,Altitude,Snow cover,Geology,Snow line
Journal
Volume
Issue
Citations 
11
12
0
PageRank 
References 
Authors
0.34
0
7
Name
Order
Citations
PageRank
Rastner, P.192.25
Rainer Prinz210.69
Claudia Notarnicola316640.15
Lindsey Nicholson401.01
Rudolf Sailer5706.50
Gabriele Schwaizer600.34
Frank Paul7195.54