Short-term glacier area changes, glacier geometry dependence, and regional climatic variations forcing, King George Island, Antarctica

LORENZ, JÚLIA L.; ROSA, KÁTIA K. DA; PETSCH, CARINA; PERONDI, CLEIVA; IDALINO, FILIPE D.; AUGER, JEFFREY DANIEL; VIEIRA, ROSEMARY; SIMÕES, JEFFERSON C.

doi:10.1590/0001-3765202320211627

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GEOSCIENCES • An. Acad. Bras. Ciênc. 95 (suppl 3) • 2023 • https://doi.org/10.1590/0001-3765202320211627 linkcopy

Short-term glacier area changes, glacier geometry dependence, and regional climatic variations forcing, King George Island, Antarctica

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This study investigates the transient snowline (TSL) altitude for summer 2020, as well as glacial area loss in King George Island Icefields since 1988 using Sentinel-1 and 2 and Landsat Thematic Mapper (TM) imagery. Trends and anomalies in atmospheric temperature, U-wind, and V-wind were examined using ERA5 solutions. Results show the wet-snow zone corresponds to values of ≤ -13dB, and 44.3% of the glacial area is located above the TSL (≥ 300 m). Glacial area for 2020 is 999.95 km², and losses in the period represent 104.9 km² (error <1%) – a retreat of 3.17 km² / year. Glaciers in Keller Peninsula and Bellingshausen Dome lost the most area (28% and 17%, respectively) and did not have a TSL in 2020; followed by Warszawa (15%), Kraków (13%), and Eastern (10%), where the TSL was verified. Percentage area loss values increased with decreases in dimensions, area above TSL, and maximum elevation. Calving glaciers with ice-flow toward deeper and steeper submarine sectors (Bransfield Strait) exhibited greater glacier variations. The trend in warming atmospheric temperature was greater in the Bransfield Strait than in the Drake Passage. TSL and retreat difference between glaciers were influenced by climatic and ocean input, as well as multiple environmental factors.

Key words
climate change; glacier fluctuations; NDSI; Sentinel; snowline

Frei Montalva Station - Climatological data
Date	Mean °C	Min. °C	Max. °C	Precipitation
03/16/2020	2.1	1.4	2.9	1.0 mm
03/17/2020	1.1	0.1	2.0	1.2 mm
03/18/2020	-0.5	-3.5	2.6	-
03/19/2020	-2.1	-3.6	-0.5	0.3 mm
03/20/2020	-3.1	-6.2	0	-

Radar zone	Backscatterring	Sensor/Type	Polarization	Band	Source
Bare-ice zone	-12 to -10 dB	ERS-1	VV	C	Smith et al. (1997)
	-13 to -10 dB	ERS-2	VV	C	Braun et al. (2000)
	-14 to -6 dB	ERS-1/2	VV	C	Rau et al. (2000)
	-17 to -15 dB	Sentinel-1 / GRD	HH	C	This study
Wet-snow zone	-22 to -6 dB	ERS-1	VV	C	Smith et al. (1997)
	-22 to -15 dB	ERS-2	VV	C	Braun et al. (2000)
	-25 to -15 dB	ERS-1/2	VV	C	Rau et al. (2000)
	< 4 dB	Sentinel-1 / GRD	HH	C	Zhou & Zheng (2017)
	-29.9, -28.54 dB	Envisat/ Sentinel-1 A and B / RADARSAT-2	HH / HH / HH	C	Zhou et al. (2021)
	⋜ -13 dB	Sentinel-1 / GRD	HH	C	This study

NDSI value	Sensor	Source
0,4	Landsat TM	Morris et al. (2006)
0,39 e 0,47	Landsat TM	Silverio & Jaquet (2012)
0,59	Landsat TM	Sanches et al. (2015)
0,55 e 0,9	Landsat TM	Rekowsky et al. (2019)
0,2 - 0,67 wet snow zone or water zoner e, 0,67 > snow zone	Sentinel-2	Hillebrand et al. (2018)
0,7 > glacier and snow zone	Sentinel-2B	This study
0,5 > glacier and snow zone	Landsat TM	This study

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