Temporal Glacier Velocity Variations and Their Controlling Factors in the Nathorstbreen Glacier System, Svalbard

Temporal variations of glacier velocity estimation are essential to understanding glacier dynamics and predicting glacier hazards. Therefore, in the current study, the continuous glacier velocities were estimated from 2014 to 2023 in the Nathorstbreen Glacier System (NGS), Svalbard, where a recent surge event was observed. Also, the study identified and quantified the factors controlling variations in annual glacier velocity. Using Landsat 8 OLI imageries, Cossi-corr, an advanced Fourier-based image-matching tool, was utilized to estimate the velocity of the NGS. After that, a multivariate regression analysis preceded by the backward stepwise selection method to identify the controlling factors of annual glacier velocity variations, considering temperature, precipitation, snowfall, and terminus fluctuations. The result indicates that the highest and lowest average yearly velocity of NGS was observed in 2021 and 2018 with a magnitude of 0.86 ± 0.11 m/day and 0.34 ± 0.18 m/day, respectively. An overall decline in velocity was observed between 2014 and 2018, followed by a resurgence between 2020 and 2022 and a final decline in 2023. The terminus of the glaciers show retreat and advancement annually, with an overall retreat of 2.9 km through the study period. Terminus fluctuations were identified as a key driver of annual glacier velocity, with a strong correlation between terminus movement in one year and velocity changes in the next. A 100-meter retreat increased the following year’s yearly velocity by around 9.2 meters, whereas a 100-meter advancement of terminus slowed down the following year's velocity with the same magnitude.