An automated methodology for differentiating rock from snow, clouds and sea in Antarctica from Landsat 8 imagery: a new rock outcrop map and area estimation for the entire Antarctic continent
As the accuracy and sensitivity of remote-sensing satellites improve, there is an increasing demand for more accurate and updated base datasets for surveying and monitoring. However, differentiating rock outcrop from snow and ice is a particular problem in Antarctica, where extensive cloud cover and...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-08-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/10/1665/2016/tc-10-1665-2016.pdf |
| Summary: | As the accuracy and sensitivity of remote-sensing
satellites improve, there is an increasing demand for more accurate and
updated base datasets for surveying and monitoring. However,
differentiating rock outcrop from snow and ice is a particular problem in
Antarctica, where extensive cloud cover and widespread shaded regions lead to
classification errors. The existing rock outcrop dataset has significant
georeferencing issues as well as overestimation and generalisation of rock
exposure areas. The most commonly used method for automated rock and snow
differentiation, the normalised difference snow index (NDSI), has difficulty
differentiating rock and snow in Antarctica due to misclassification of
shaded pixels and is not able to differentiate illuminated rock from clouds.
This study presents a new method for identifying rock exposures using
Landsat 8 data. This is the first automated methodology for snow and rock
differentiation that excludes areas of snow (both illuminated and shaded),
clouds and liquid water whilst identifying both sunlit and shaded rock,
achieving higher and more consistent accuracies than alternative data and
methods such as the NDSI. The new methodology has been applied to the whole
Antarctic continent (north of 82°40′ S) using Landsat 8 data to
produce a new rock outcrop dataset for Antarctica. The new data (merged with
existing data where Landsat 8 tiles are unavailable; most extensively south
of 82°40′ S) reveal that exposed rock forms 0.18 % (21 745 km<sup>2</sup>)
of the total land area of Antarctica: half of previous estimates. |
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| ISSN: | 1994-0416 1994-0424 |