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Title: Semi-automated tracking of iceberg B43 using Sentinel-1 SAR images via Google Earth Engine
Abstract. Sentinel-1 C-band synthetic aperture radar (SAR) images can be used to observe the drift of icebergs over the Southern Ocean with around 1–3 d of temporal resolution and 10–40 m of spatial resolution. The Google Earth Engine (GEE) cloud-based platform allows processing of a large quantity of Sentinel-1 images, saving time and computational resources. Inthis study, we process Sentinel-1 data via GEE to detect and track the drift of iceberg B43 during its lifespan of 3 years (2017–2020) in the Southern Ocean. First, to detect all candidate icebergs in Sentinel-1 images, we employ an object-based image segmentation (simple non-iterative clustering – SNIC) and a traditional backscatter threshold method. Next, we automatically choose and trace the location of the target iceberg bycomparing the centroid distance histograms (CDHs) of all detected icebergsin subsequent days with the CDH of the reference target iceberg. Using thisapproach, we successfully track iceberg B43 from the Amundsen Sea to the Ross Sea and examine its changes in area, speed, and direction. Threeperiods with sudden losses of area (i.e., split-offs) coincide with periodsof low sea ice concentration, warm air temperature, and high waves. Thisimplies that these variables may be related to mechanisms causing thesplit-off of the iceberg. Since the iceberg is generally surrounded bycompacted sea ice, its drift correlates in part with sea ice motion and wind velocity. Given that the bulk of the iceberg is under water (∼30–60 m freeboard and ∼150–400 m thickness), its motion ispredominantly driven by the westward-flowing Antarctic Coastal Current, which dominates the circulation of the region. Considering the complexity of modeling icebergs, there is a demand for a large iceberg database to better understand the behavior of icebergs and their interactions with surrounding environments. The semi-automated iceberg tracking based on the storage capacity and computing power of GEE can be used for this purpose.  more » « less
Award ID(s):
1835784
NSF-PAR ID:
10308730
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
The Cryosphere
Volume:
15
Issue:
10
ISSN:
1994-0424
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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The drill sites on the continental rise were in the path of numerous icebergs of various sizes that frequently forced us to pause drilling or leave the hole entirely as they approached the ship. The overall downtime caused by approaching icebergs was 50% of our time spent on site. 3. An unfortunate injury to a member of the ship's crew cut the expedition short by one week. Recovery of core on the continental rise at Sites U1532 and U1533 cannot be used to precisely indicate the position of ice or retreat of the ice sheet on the shelf. However, these sediments contained in the cores offer a range of clues about past WAIS extent and retreat. At Sites U1532 and U1533, coarse-grained sediments interpreted to be ice-rafted debris (IRD) were identified throughout all recovered time periods. 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