Icebergs on the Move
The large tabular iceberg A23a calved from the Filchner–Ronne Ice Shelf in 1986. After its calving, the research base Druzhnaya I, which was placed on this iceberg, had to be removed and was renamed to Druzhnaya III. For many years the iceberg remained stuck on the seabed before it started moving in 2020. With an area of almost 4,000 square kilometres, it was by 2024 one of the largest icebergs ever monitored.
Late in 2020, A23a started its journey towards north, roughly following the coastline of the Antarctic Peninsula. In November 2023, the iceberg moved past the northern tip of the Antarctic Peninsula, heading toward north. During its tour away from Antarctica, A23a will reach warmer waters and will subsequently melt.
While the dissolution of the ice shelves does not directly contribute to the seawater level (the melted water replaces only the volume of the submerged part of the ice), it plays an important indirect role as the shelves function as a stabilising barrier for the glaciers flowing towards the sea. A loss of this barrier can lead to an enhanced ice flow.
Exercises
- Satellite Map:
- Look at the satellite map and zoom in to the true colour Sentinel-3 image of the iceberg. Which different features and landcover types can you identify? How can you discern them? Hint: open water appears in very dark blue, drifting ice in a blueish white, and large icebergs in white; ice and snow on land can be identified by the relief they show. Additionally, clouds cover parts of the image.
- Look at the iceberg A23a in the upper part of the map. Use the measure tool to determine (i) its width and (ii) estimate its area. Compare the measured values with features in your home region, e.g. your home town.
- Use the layer selector to switch on the layer group “Sentinel-1 data”. Select and deselect the individual radar image layers and compare them with the optical Sentinel-3 image. How are ice and water surfaces represented in the radar images?
- Look at the map below showing the path of the iceberg. Use the measure tool to give an estimation of the length of the way the iceberg drifted during 2022 and 2023.
- Copernicus Browser:
- Open the case study area in the Copernicus Browser.
- Find the most recent Sentinel-2 dataset covering the area displayed in the satellite map.
- Select a true colour visualisation.
- Can you identify additional, recent changes in the area?
- Select the false colour infrared representation. Can you identify the land-use of the most intensely vegetated areas (represented by bright red colours)?
Links and Sources
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PDF document of the case study (includes exercises): English, German, French, Italian, Spanish |
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This case study is covered on page 45 of the printed ESA Schoolatlas – download the PDF document of the page: English, German, French, Italian, Spanish |
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