Presently, 10 percent of land area on Earth is covered with glacial ice, including glaciers, ice caps and the ice sheets of Greenland and Antarctica. Of course, this percentage decreases due to climate change. Areas filled with glaciers cover over 15 million square kilometers, while they store about 75 percent of the world’s fresh water.
Glaciers are an essential part of our living environment and especially the cryosphere. Although not everybody is familiar with glaciers, they are considered as very important natural regions that need to be preserved and monitored. Scientists analyzing glaciers can better model and understand the climate and it’s changes and dive into earth’s long forgotten climate history!
Remote sensing images acquired from different platforms (satellite, aircraft) using sensors that operate in different spectral regions (visible, infrared, microwave) have been widely used to study glaciers, e.g. to measure ice thickness, surface ice velocities, and changes in surface elevation over time. Remote sensing techniques have been used for spectral characterisation of different snow and icefaces, preliminary inventory of glaciers including aerial extent and position of large crevasses, and for mapping and monitoring glacial variations especially at the glacier margins and terminus location.
The images below are different time stamps of the same area. In the left you have the natural colour (as you would see it with you own eyes) and in the right you see the result of an index called NDGI (Normalised Difference Glacier Index).
Multi-temporal Sentinel 2 imagery data allow the terminus and area mapping of glaciers as well as the study of the spectral characteristics of snow and ice in the spatial resolution of 10 m — 20 m.
For those interested in applications concerning cryosphere, GEO University has a course about helping you deeply understand glacier and snow cover mapping using remote sensing. It is called ‘Glacier Mapping using Earth Observation Satellites’.
Its structure is as follows:
Initially it focuses on the basic principles, i.e. how snow interacts with the electromagnetic radiation. Then, specific methodologies that allow you to map glaciers and snow covered areas using multispectral satellite images are showcased. From the practical side, our learning is also focused on how to perform these methods in ESA’s SNAP software. Ready-to-use XML files for the SNAP GPT are also provided!