1Centre of Studies in Resources Engineering, IIT Bombay, Mumbai - 400076, India;
2Institute of Geography, Russian Academy of Sciences, Moscow, Russia;
3Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande, Brazil;
* Correspondence: gulab.singh@iitb.ac.in
Abstract:
The highly dynamic nature of snow requires frequent observations to study its various 12 properties. Keeping this in mind, the present investigation presents results from the analysis of 13 polarimetric parameters for the development of snow depth (SD) inversion model for SD retrieval. 14 Snow depth retrieved using ground penetrating radar (GPR) at 500 MHz over Austre 15 Grønfjordbreen (East Grenfjord glacier) in Svalbard region was used to understand the behaviour 16 of certain polarimetric parameters. Good degree of positive correlation is achieved between field 17 measured SD and polarimetric parameters of coherence and normalized volume scattering power 18 (R2 = 0.84 and R2 = 0.73 respectively.) Using the scattering powers obtained from the six-component 19 model-based decomposition (6SD), the heterogeneity and anisotropic behaviour in the firn areas 20 are also explained. Further, based on the analyses shown in this work, polarimetric parameter 21 based SD inversion algorithm have been proposed and validated. The univariate model with 22 co-polarization coherence has the highest correlation (R2=0.84, RMSE=0.18). We have even tested 23 several multivariate models for the same, to conclude that a combination of coherence, normalized 24 volume and double-bounce scattering have a high correlation with SD (R2 = 0.84, RMSE=0.18). 25 Additionally, a temporal and spatial variability in SD has also been observed from three 26 polarimetric SAR images acquired between April 4th 2015 and May 15th 2015 over the Western 27 Nordenskiöld Land region. Increase in snow depth corresponding to snow precipitation events are 28 also detected using the POLSAR data. 29
Keywords: Snow depth; Svalbard; GPR; POLSAR; decomposition
Bala Raju Nela 1,Debmita Bandyopadhyay 1,Gulab Singh 1,*,Andrey F. Glazovsky 2,Ivan I. Lavrentiev 2,Tatiana E. Kromova 2 andJorge Arigony-Neto 3
1Centrer of Studies in Resources Engineering, IIT Bombay, Mumbai 400076, India
2Institute of Geography, Russian Academy of Sciences, Moscow 119991, Russia
3Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande 96203-900, Brazi
Water 2019, 11(12), 2466; https://doi.org/10.3390/w11122466
Received: 30 September 2019 / Revised: 7 November 2019 / Accepted: 13 November 2019 / Published: 23 November 2019
(This article belongs to the Special Issue Impacts of Climate Change on Water Resources in Glacierized Regions)
Abstract
Glacier velocity is one of the most important parameters to understand glacier dynamics. The Severnaya Zemlya archipelago is host to many glaciers of which four major ice caps encompassing these glaciers are studied, namely, Academy of Sciences, Rusanov, Karpinsky, and University. In this study, we adopted the differential interferometric synthetic aperture radar (DInSAR) method utilizing ALOS-2/PALSAR-2 datasets, with a temporal resolution of 14 days. The observed maximum velocity for one of the marine-terminating glaciers in the Academy of Sciences Ice Cap was 72.24 cm/day (≈263 m/a). For the same glacier, an increment of 3.75 times the flow rate was observed in 23 years, compared to a previous study. This has been attributed to deformation in the bed topography of the glacier. Glaciers in other ice caps showed a comparatively lower surface velocity, ranging from 7.43 to 32.12 cm/day. For estimating the error value in velocity, we selected three ice-free regions and calculated the average value of their observed movement rates by considering the fact that there is zero movement for ice-free areas. The average value observed for the ice-free area was 0.09 cm/day, and we added this value in our uncertainty analysis. Further, it was observed that marine-terminating glaciers have a higher velocity than land-terminating glaciers. Such important observations were identified in this research, which are expected to facilitate future glacier velocity studies. View Full-Text
Keywords: glacier movement; differential SAR interferometry; marine-terminating glacier