Seven-year variation in glacier surface velocity at Narsap Sermia in Southwest Greenland

ABSTRACT

Glacier velocity is a critical factor closely related to ice dynamics of the Greenland ice sheet (GrIS). We present variations of ice velocity using space-based synthetic aperture radar (SAR) observations from July 2013 to September 2020. We focus on a tidewater outlet glacier of Narsap Sermia (NS), located in southwest Greenland, which is experiencing significant ice loss. A time series of high spatiotemporal resolution maps of ice velocity was traced by using an offset tracking approach with seven-year SAR acquisitions to understand glacier dynamics in time. We observed seasonal variations showing a dramatic increase in late spring (May) and early summer (June) followed by a sharp decrease in late summer (September). The seasonal variation was confirmed through Seasonal and Trend decomposition using Loess (STL) analysis. Overall, the NS glacier experienced a gradual speed-up of ice velocities. The ice velocity increased by 0.1–0.3 km/year from 2015 to 2017, then after a temporary decrease in 2018, the velocity moved faster by 0.9 km/year in 2020. The speed of glacier movement accelerated as it approached the tidal terminus of the glacier, showing approximately 6.0 km/year in 2020. The ice speed in 2020 increased by 0.9 km/year at the terminus region compared with 2014. We also discuss the relationship between the glacier velocity and temperature data such as air, land surface, and sea surface temperatures.

KEYWORDS:

• Ice velocity
• Narsap sermia
• offset tracking
• SAR
• glacier
• Time series analysis

Acknowledgments

The authors thank the German Space Agency (DLR), the Italian Space Agency (ASI), and the uropean Space Agency (ESA) for providing the TerraSAR-X/TanDEM-X (PID: GEO3061), COSMO-SkyMed and Sentinel-1 data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, SHH, upon reasonable request.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15481603.2023.2207301.

Additional information

Funding

This work was supported by National Research Foundation of Korea (NRF) grant funded by the Korean Government (MSIT) under Grant [NRF-2023R1A2C1003609] and was funded by the Meteorological/Earthquake See-At Technology Development Research [Grant KMI2018-02710].