Mapping Radar Glacier Zones and Dry Snow Line in the Antarctic Peninsula Using Sentinel-1 Images

Abstract

Surface snowmelt causes changes in mass and energy balance, and endangers the stabilities of the ice shelves in the Antarctic Peninsula (AP). The dynamic changes of the snow and ice conditions in the AP were observed by Sentinel-1 images with a spatial resolution of 40 m in this study. Snowmelt detected by the special sensor microwave/imager (SSM/I) is used to study the relationship between summer snowmelt and winter synthetic aperture radar (SAR) backscatter. Radar glacier zones (RGZs) classifications were conducted based on their differences in liquid snow content, snow grain size, and the relative elevations. We developed a practical method based on the simulations of a microwave scattering model to classify RGZs by using Sentinel-1 images in the AP. The summer snowmelt detected by SSM/I and Sentinel-1 data are compared between 2014 and 2015. The SSM/I-derived melting days is used to validate the winter dry snow line (DSL). RGZs derived from Sentinel-1 images suggest that snowmelt expanded from inland of the Larsen C Ice Shelf to the coastal area, whereas an opposite direction was found in the George VI Ice Shelf. The long melting season in the grounding zone of the Larsen C Ice Shelf may result from the adiabatically-dried föhn winds on the east side of the AP. As the uppermost limit of summer snowmelt, DSL was mapped based on the winter Sentinel-1 mosaic of the AP. Compared with the SSM/I-derived melting days, the winter DSL mainly distributed in the areas melted for one to three days in summer. DSL elevations on the Palmer Land increased from south to north.

Antarctic Snowmelt Detected by Diurnal Variations of AMSR-E Brightness Temperature

“…On the Larsen C Ice Shelf, the most intensive snowmelt was found in the grounding zone. The dry föhn winds flow across the Antarctic Peninsula, flush away the cool air and warm the snow surface, leading to the extremely high melt rates in the grounding zone [12,78]. On the contrary, snowmelt at high latitudes showed significant annual variations, especially in the Ross and Ronne Ice Shelves where snowmelt only lasted for a few days (see Figures 6 and 8).…”

An Integrated Shadow-Adjusted Snow-Aging Index for Alpine Regions

“…Two field work campaigns were carried out in the northern and southern branches of the MRB during the snow accumulation (10-17 December 2013) and ablation (15)(16)(17)(18)(19)(20)(21)(22) March 2014) periods. The field work included the acquisition of reflectance spectra and collection of morphological and physical parameters, and other environmental variables [49,50].…”

“…Further, the "subpixel snow-cover information", "empirical relationship assumptions" [15,16], and "spectral unmixing" [17] models have been extensively applied for the inversion of the fractional snow cover. Transient snowline altitude and glacier elevation can be extracted by combining optical and synthetic aperture radar (SAR) imagery as well as DEM data [18]. Passive microwave-based models can penetrate clouds and provide measurements in shadowed regions and hence, are useful for inversion of the snow depth [19,20], snow water equivalent (SWE) [21], and snow cover storage [22].…”

Satellite Remote Sensing of the Greenland Ice Sheet Ablation Zone: A Review

“…Mapping of surface zones or facies, such as dry snow, wet snow, and bare ice, was pioneered by Benson [35], and later mapped across the GrIS using both ERS SAR imagery [50] and Seasat-A scatterometer backscatter [311]. In contrast to the climatological facies of Benson [35], the concept of radar glacier zones was introduced to distinguish dynamic zones driven by the seasonal cycle of surface melt onset, surface roughening, and snowline migration, thereby revealing the seasonal extent of the bare ice ablation zone [312][313][314]. Multi-angular optical reflectance, together with derived surface roughness, provides an independent method to map glacier zones on the GrIS with particular relevance to ablation zone studies owing to the unique ability of angular reflectance to detect crevasse fields and the lower limit of superimposed ice [53].…”