Abstract
The temporal and spatial variability of the Antarctic coastline is a clear indicator of change in extent and mass balance of ice sheets and shelves. In this study, the Canny edge detector was utilized to automatically extract high-resolution information of the Antarctic coastline for 2005, 2010, and 2017, based on optical and microwave satellite data. In order to improve the accuracy of the extracted coastlines, we developed the Canny algorithm by automatically calculating the local low and high thresholds via the intensity histogram of each image to derive thresholds to distinguish ice sheet from water. A visual comparison between extracted coastlines and mosaics from remote sensing images shows good agreement. In addition, comparing manually extracted coastline, based on prior knowledge, the accuracy of planimetric position of automated extraction is better than two pixels of Landsat images (30 m resolution). Our study shows that the percentage of deviation (<100 m) between automatically and manually extracted coastlines in nine areas around the Antarctica is 92.32%, and the mean deviation is 38.15 m. Our results reveal that the length of coastline around Antarctica increased from 35,114 km in 2005 to 35,281 km in 2010, and again to 35,672 km in 2017. Meanwhile, the total area of the Antarctica varied slightly from 1.3618 × 107 km2 (2005) to 1.3537 × 107 km2 (2010) and 1.3657 × 107 km2 (2017). We have found that the decline of the Antarctic area between 2005 and 2010 is related to the breakup of some individual ice shelves, mainly in the Antarctic Peninsula and off East Antarctica. We present a detailed analysis of the temporal and spatial change of coastline and area change for the six ice shelves that exhibited the largest change in the last decade. The largest area change (a loss of 4836 km2) occurred at the Wilkins Ice Shelf between 2005 and 2010.
Highlights
Knowledge of the coastline location forms the basis for coastal assessments and characterization of the land-ocean transition zone, and provides information on continental and coastal area [1]
We have presented an updated Antarctic coastline based on high-resolution multi-source satellite imagery
Our procedures involve an automatic coastline extraction based on the Canny edge detection algorithm with modification to use a multi-component digital procedure
Summary
Knowledge of the coastline location forms the basis for coastal assessments and characterization of the land-ocean transition zone, and provides information on continental and coastal area [1]. The Antarctic coast is characterized by numerous ice shelves, which are permanent floating extensions of the glacial ice sheet onto the ocean. These ice shelves play an important role for ice sheet dynamics and mass balance. Defining the Antarctic coastline becomes crucial for assessment of the overall glacial mass budget and, ice sheet mass balance [2]. The coastline of the Antarctica is defined as the boundary between the ocean and the ice sheet, which includes ice shelves. Coastline monitoring is of great importance to assess changes in the coastline configuration and ice sheet mass balance
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