Abstract
During the 32nd Chinese National Antarctic Research Expedition (CHINARE 32), we used shallow ice radar within the East Antarctic region extending from Zhongshan Station to Kunlun Station and obtained the distribution of shallow isochronous layers for the first time. Taking a typical area as a case study, this article describes the complete workflow used in radar data processing, including the extraction of isochronous layers. Moreover, information on the depths of the isochronous layers is obtained by referring to ice core data. The results show the large-scale distribution of shallow isochronous layers in East Antarctica. Moreover, the isochronous layers formed in specific years can be traced. During the analysis, it is found that the isochronous layers sometimes display sharp slopes. We also present several maps of the shallow isochronous layers within three selected regions, including a region surrounding Dome A, a region 100 km away from Dome A and a region corresponding to the Lambert Glacier, and we show the large-scale distribution of the layers and detailed depth information for each layer. Comparing the maps of the isochronous layers within the three regions shows that the isochronous layers are relatively stable in the Dome A region and change more intensely in the Lambert Glacier region and that sharper slopes occur frequently in areas close to Dome A. The analysis of the distribution of the shallow isochronous layers and age-depth information from different regions provides important data that support the calculation of large-scale accumulation rates in the Antarctic region.
Highlights
The density of ice formed in different periods differs within glaciers [Paren and Robin, 1975], and the different characteristics caused by variations in density or conductivity, as well as variations in crystal orientation fabric (COF), can result in the detection of distinct layers from electromagnetic-wave reflection signals [Paren and Robin, 1975; Siegert, 1999; Fujita et al, 1999; Vaughan et al, 1999]
To determine the continuous isochronous features of a shallow ice sheet over longer distances, and to add the available data on East Antarctic ice sheet dynamics and surface mass balance (SMB) [Gogineni et al, 2007], the inland Kunlun team of the 32nd Chinese National Antarctic Research Expedition (CHINARE 32) used Frequency-Modulated Continuous-Wave (FMCW) sounding radar to fully observe the ice sheet along a route extending from the inland base (8 km from Zhongshan Station at the margin of the ice sheet) to Kunlun Station near Dome A (Figure 1), and obtained echograms of shallow isochronous layers in the East Antarctic with a total distance of 1280 km from the coast to the inland
This paper mainly describes the shallow exploration radar observation work conducted by CHINARE 32 from Zhongshan Station to Kunlun Station in 2015
Summary
The density of ice formed in different periods differs within glaciers [Paren and Robin, 1975], and the different characteristics caused by variations in density or conductivity, as well as variations in crystal orientation fabric (COF), can result in the detection of distinct layers (isochronous layers) from electromagnetic-wave reflection signals [Paren and Robin, 1975; Siegert, 1999; Fujita et al, 1999; Vaughan et al, 1999]. To determine the continuous isochronous features of a shallow ice sheet over longer distances, and to add the available data on East Antarctic ice sheet dynamics and surface mass balance (SMB) [Gogineni et al, 2007], the inland Kunlun team of the 32nd Chinese National Antarctic Research Expedition (CHINARE 32) used FMCW sounding radar to fully observe the ice sheet along a route extending from the inland base (8 km from Zhongshan Station at the margin of the ice sheet) to Kunlun Station near Dome A (Figure 1), and obtained echograms of shallow isochronous layers in the East Antarctic with a total distance of 1280 km from the coast to the inland These data are of great value for analysis the temporal and spatial variability of SMB and provide a basis for reconstructing Antarctic climates and deducing the effects of future climate change. These data provide the foundation for reconstructing past climates in the Antarctic and analyzing the flow history
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