Topic 3c: Ice Sheet Topography and Height
In this video scientist Louise Sørensen, senior researcher in the Geodesy and Earth Observation division at DTU Space, explains how scientists use satellite altimetry to measure changes in the ice sheet such as height.
Topography is a detailed map of the surface features of land. Ice sheet topography helps to track changes in ice sheets and provides important information for modelling glacier dynamics.
Ice sheet topography can be a good indicator to show how the ice sheets are responding to climate change.
In peak melt season on the East Antarctic Ice Sheet in January 2017 over 65,000 meltwater lakes, known as supraglacial lakes, were spotted using 5 million km2 of high-resolution satellite imagery from Sentinel-2. The largest of these supraglacial lakes measured over 70 km2. This was a higher number of lakes than usual for the East Antarctic Ice Sheet, which is colder than the Greenland and Antarctic Peninsula ice sheets.
Satellite altimetry can be used to measure the thickness of an ice shelf. It is important to measure the height of ice shelves because it shows how much they are melting.
Altimetric LIDAR is the method of using light to measure height. Pulses of laser light are emitted from a satellite, and the height of the ice can be measured by recording the amount of time for the light to be emitted, reflected and received back to the satellite.
CryoSat-2 uses radar altimetry to monitor ice sheet elevation.
In 2017, scientists discovered inverted canyons under Antarctica’s Dotson Ice Shelf using data from Sentinel-1 and CryoSat. While the surface of the ice shelf looked flat, the data suggests that ice was not melting in a uniform pattern.
For more information about ice sheet photography, you can watch Cryosat-2: Measuring Changes In Ice Thickness, a lecture by Professor Andrew Shepherd that is available as part of The Frozen Frontier: Monitoring the Greenland Ice Sheet From Space, another MOOC produced by Imperative Space for ESA.
Featured Educator:
- Dr Louise Sandberg Sørensen
- Dr Sebastian Bjerregaard Simonsen
(This video was partly filmed remotely during COVID-19 lockdown conditions)
Take the quiz
You can take the end of week quiz by clicking on the quiz tab located below the video.
Sentinel 2A
CRYOSAT-2
SENTINEL 1A
Course topics
The core videos of this course are labelled as topic videos.
We have also provided a range of optional further reading, links, and additional resources to help consolidate your learning. Here is a summary of what is available:
Topic links and resources
In each topic, once you have watched the video and read the accompanying text, you will find the following information:
- Optional Further Reading: These are external links to further reading.
- Featured Images and Animations: Below the text on each video page, you’ll find the featured images and featured animations.
- Interactives: On the 'Interactives' tab on relevent topic pages, you will find a satellite tracking application showing the current location of the satellites, a data viewer from the ESA WEkEO platform, as well as a data viewer, specially created for this course, allowing you to explore a selection of data relevant to the themes and topics in this course. (Please note that due to maintenance, the data viewer is currently unavailable).
Quizzes and comments
- Quizzes: At the end of each week there will be a quizz consisting of around five questions. These will help you consolidate your understanding of new topics, but are not scored. The feedback given with each answer also will also provide you with important information.
Weekly interactive exercises
At the end of each week, we have included a guided exercise, using interactive apps available on other websites, to help you become more familiar with looking at and working with EO datasets. You will be guided through the process of searching for, comparing and drawing conclusions from data relevant to some of the topics covered in that week.
- Denman Glacier: Deepest Point On Land Found In Antarctica - BBC
- New Maps Show How Greenland’s Ice Sheet Is Melting From The Bottom Up - Scientific American
- NASA's IceSat Space Laser Tracks Water Depths From Orbit - BBC
- Photo Of Sled Dogs Walking Through Water Shows Reality Of Greenland’s Melting Ice Sheet - CNN
- Greenland Map Captures Changing Arctic In Fine Detail - BBC
- ESA's CCI Project - Greenland Ice Sheet
- NASA's IceSat Space Laser Makes Height Maps of Earth - BBC
- Ice Sheets Could Add 39 Centimeters To Sea Level By 2100 - Leeds University
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Greenland’s bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage.
Additional Optional Material: Topography of sea ice and the interaction between atmosphere, ice and ocean effects drag, presentation from Alek Petty , Michel Tsamados, Nathan Kurtz
