Extraction and Analysis of the Three-Dimensional Features of Crevasses in the Amery Ice Shelf Based on ICESat-2 ATL06 Data

Abstract

Crevasse is an important characteristic of ice shelf internal structure, and also an important index to measure the stability of ice shelf. This study aims to detect crevasses from ICESat-2 data and obtain three-dimensional features of crevasse. Firstly, the change of along-track surface slope and the depth threshold is combined to obtain the crevasse bottom points and the crevasse edge points; Secondly, the distance between the crevasse bottom points and the fitted ice shelf surface by crevasse edge points is used as the crevasse bottom points depth; Thirdly, the crevasse direction is judged by the strong and weak laser position and the width is calculated by the crevasse edge points and crevasse direction. The Amery Ice Shelf(AIS) is chosen as the test area to validate the method by ATL06 data, combined with the Landsat-8 optical image. The depth of the crevasses in the Amery Ice Shelf is about range from 2.0m to 60.0m, and the width is mainly 400 to 1600m, and the width and length of L3 rift has dramatically change which is an indicator that the AIS is in a new calving cycle. The method in this paper can accurately obtain three-dimensional information of the crevasses, find crevasses with abnormal changes in depth and width, and provide effective help for predicting the calving of the ice shelf.

Damage detection on antarctic ice shelves using the normalised radon transform

“…It is this characteristic that allows NeRD to include the multiple types of damage features without losing comprehensible interpretation. Moreover, as high values of the detected damage parameter D seem to correlate to large (deep) damage features and low values to small (shallow) features, D could potentially be linked to the scalar damage factor used in CDM modelling (Borstad et al, 2012(Borstad et al, , 2013(Borstad et al, , 2016Sun et al, 2017) or to vertical crevasse information obtained from laser altimetry studies (Li et al, 2021;Wang et al, 2021). NeRD, however, is less suited to detect wide features with gradual slopes, especially compared to the CNN fracture map of Lai et al (2020).…”

“…Damage areas typically consist of highly crevassed areas, rifts and open fractures containing dense ice mélange (Lhermitte et al, 2020; Remote sensing data provides the possibility to detect fractures and damage areas across Antarctic ice shelves and the ice sheet. Where laser altimetry is used to map vertical properties, quantifying the continuous distribution of fractures in the horizontal dimension remains unsolved (Wang et al, 2021;Herzfeld et al, 2021;Li et al, 2021). Assessing horizontal properties of fractures and damage from satellite imagery can be a complicated task due to three major challenges.…”

Evaluation of the Emissions State of a Satellite Laser Altimeter Based on Laser Footprint Imaging

“…Satellite laser altimetry is an important component of Earth observation and remote sensing because it is characterized by good monochromaticity, good coherence, good directivity, high brightness, and ability to rapidly obtain large-scale and high-precision elevation data. This technique has been widely used in polar change monitoring [1], atmospheric vertical distribution detection [2,3], forest biomass inversion [4], and lake water-level change monitoring [5]. Benefiting from the experience and technical precipitation of previous laser altimeter satellites [6][7][8][9][10], the GaoFen-7 (GF-7) satellite was successfully launched in November 2019.…”

“…Laser emission state monitoring includes two aspects. (1) Pointing change monitoring: laser pointing is closely related to the positioning accuracy, which mainly results from monitoring the change in the centroid of the laser spot. For the GF-7 satellite laser footprint image, traditional algorithms, including the GCM and ellipse-fitting method [21][22][23][24], encounter difficulties in accurately estimating the centroid coordinates due to the influence of complex background objects.…”

Influence of Atmospheric Scattering on the Accuracy of Laser Altimetry of the GF-7 Satellite and Corrections

“…It has received significant attention due to its capacity to obtain sub-meter or even centimeter-scale elevation measurement accuracies [1,2]. In 2003 and 2018, the National Aeronautics and Space Administration (NASA) launched the ice, cloud, and land elevation satellite (ICESat) and ICESat-2, which have yielded several scientific achievements regarding changes in polar ice sheet thicknesses, global tree heights, biomass inversion, global elevation control point acquisitions, and lake water level monitoring [3][4][5]. ICESat-2 is equipped with an advanced topographic laser altimeter system (ATLAS) that uses a new photon counting system.…”