Identification of seasonal snow phase changes from C-band SAR time series with dynamic thresholds

BELTRAMONE, GIULIANA; FRERY, ALEJANDRO; ROTELA, CAMILO; GERMAN, ALBA; BONANSEA, MATIAS; SCAVUZZO, CARLOS MARCELO; FERRAL, ANABELLA

IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Lugar: New York; Año: 2023

1939-1404

In cryospheric studies, the most critical variable is estimating the beginning and evolution of the seasonal snow accumulation and its melting process. We propose and evaluate a new method for identifying seasonal snow cover phase changes in the Argentinean Andes using time series of Sentinel-1 Synthetic Aperture Radar data available in the Google Earth Engine platform. We used meteorological and optical Sentinel 2 data to validate snow presence. Firstly, we investigated seasonal snow cover dynamics in different regions of interest (ROIs). We identified three land surface cover periods: bare soil, dry snow, and melting snow. This finding is significant because other studies show that bare soil and dry snow have similar responses in C band. Our methodology uses time series derivatives and their positive and negative anomalies. Finally, we compare our results with those obtained with a fixed threshold change detection approach. Our method detects the phase change between bare soil and dry snow in 75% of the ROIs, while a fixed threshold of −2 dB only in 42% of the cases. Furthermore, the derivative method also detects in 92% of the series the beginning of the melting period, showing that it is a promising methodology for operative systems.