INTERPRETATION SIGNS OF GROUNDWATER ICINGS ON SENTINEL-1 RADAR IMAGES ON EXAMPLES OF THE VERKHNYAYA NERUNGRA AND SAMOKIT AUFEIS OF SOUTHERN YAKUTIA
L.A. Gagarin, N.E. Baishev, A.E. Melnikov
Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
Keywords: icing (aufeis), radar image, remote sensing research methods, Sentinel-1, Sentinel-2, normalized difference snow index
Abstract
Synthetic aperture radar (SAR) images Sentinel-1 were used to detail the structure of aufeis and characteristic features of aufeis landscapes in the valleys of Verkhnyaya Neyungri and Samokit rivers (southern Yakutia). Based on the results of preliminary image analysis, the ranges of typical backscatter signals within the ice glade were established, and representative points characterizing various components of the ice landscape were chosen. The type of surface of the aufeis landscape (ice, open water, snow cover, rock, etc.) was preliminarily diagnosed using Sentinel-2 images. During fieldwork, the vertical structure of the aufeis landscape and its surface were studied at the chosen test plots. As a result, the ranges of backscattering of the radio signal for co-polarization (VV) and cross-polarization (VH) modes characteristic of the four types of the aufeis landscape were determined. Based on SAR images, the structure of the aufeis body could be detailed: areas of river flow under the ice and places of groundwater discharge were identified. At the final stage, aufeis areas at the end of winter in the Samokit and Verkhnyaya Neryungri river valleys were determined based on Sentinel-1 SAR images and the normalized difference snow index (NDSI) calculated from Sentinel-2 images; the discrepancy between the obtained estimates was assessed.
|
