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GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 17-6
Presentation Time: 9:50 AM

SPACEBORNE POLARIMETRIC SAR INTERFEROMETRY FOR SNOW DEPTH RETRIEVAL IN THE NORTHWESTERN HIMALAYAN WATERSHED


MAJUMDAR, Sayantan, Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, Missouri S&T, Rolla, MO 65409, THAKUR, Praveen K., Water Resources Department, Indian Institute of Remote Sensing (IIRS), ISRO, 4 Kalidas Road, Dehradun, 248001, India, CHANG, Ling, Earth Observation Science, Faculty of Geo-information Science and Earth Observation (ITC) of the University of Twente, ITC-2005, P.O. Box 217, Enschede, 7500 AE, Netherlands, KUMAR, Shashi, Photogrammetry and Remote Sensing Department, Indian Institute of Remote Sensing (IIRS), ISRO, 4 Kalidas Road, Dehradun, 248001, India and SMITH, Ryan G., Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, 1400 N Bishop, 129 McNutt Hall, Rolla, MO 65409

Snow depth (SD) is an important physical property of snow which is predominantly utilized in hydrologic studies. However, due to the terrain difficulties and hydrometeorological conditions, accurate large-scale SD estimation is still an ongoing research element in the cryosphere domain.

Spaceborne synthetic aperture radar (SAR) systems have been extensively used to measure different snow physical properties. Still, previously developed polarimetric SAR (PolSAR) and interferometric SAR (InSAR) techniques are affected by volume decorrelation in rugged surfaces. Therefore, the polarimetric SAR interferometry (Pol-InSAR) technique can be effectively applied to obtain the volumetric SD. In this work, the standing (or old) snow depth (SSD) is computed using the single-baseline Pol-InSAR based hybrid Digital Elevation Model (DEM) differencing and coherence amplitude inversion model.

Here, the study area (~96 km2) surrounding Dhundi (Beas watershed, India) is selected from the TerraSAR-X, TanDEM-X coregistered bistatic scene acquired on January 8, 2016. Since the Pol-InSAR model involves several user-defined parameters, necessary sensitivity analyses are performed for fine-tuning purposes.

Furthermore, the summer (June 8, 2017) and wintertime (January 8, 2016) images are used to quantitatively compare the different scattering mechanisms. This is performed using the dual-pol H-𝛼 decomposition and unsupervised Wishart classification techniques. The results indicate that snow clearly increases the high entropy anisotropic volume scattering (by 5.11%) and reduces the medium entropy volume scattering (by 7.01%). Similarly, the other scatterings are also affected in the presence of snow.

Additionally, the reference ALOS PALSAR DEM is used to analyze the elevation and local incidence angle errors using the field measurements. Noticeably, these errors do not significantly alter the SSD values because of the ensemble averaging operations. Also, the Pol-InSAR model is improved by using the secant root-finding algorithm, leading to more precise and accurate SSD estimates.

Evidently, the mean SSD obtained over the 3✕3 (81 m2) window at Dhundi is consistent with the in-situ measurement. This showcases the practicability of the improved Pol-InSAR model for estimating the SSD over undulating terrains.

Handouts
  • GSA_PPT_Sayantan.pptx (47.2 MB)

    • Session No. 17

    T138. Remote Sensing Applications in Hydrology
    Sunday, 22 September 2019: 8:00 AM-12:00 PM
    Room 104AB, West Building (Phoenix Convention Center)
    Geological Society of America Abstracts with Programs. Vol. 51, No. 5
    doi: 10.1130/abs/2019AM-338916
    © Copyright 2019 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
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