Flow analysis of Icelandic glaciers using synthetic aperture radar focused on climate seasonality and ELA setting.

Abstract:

Glaciers in Iceland provide of tourism income, water resource in aluminum production and that for hydropower generation. Because glacier change is a proxy of climate change, mass balance and velocity of the Iceland glaciers have been surveyed for more than 30 years. In this study, we focused on two outlet glaciers, the Skeiðarárjökull and Breiðamerkurjökull in the Vatnajökull. A remote sensing technique was conducted to investigate the velocity of these two glaciers from June to August 2019. The Grand Range Detected products in Sentinel-1A's Interferometric Wide Swath Data were obtained and monthly-observed tracking flows were calculated by the offset tracking method by means of the analysis software Sentinel Application Platform. In addition Landsat-8 images were referred for validation.Our result shows almost no flow in the terminus area of Skeiðarárjökull. The flow velocity increases as the distance from the end of the glacier increases, which exceeds 1.0 m day^-1 at the maximum. In the Breiðamerkurjökull as well, the flow velocity increased as the distance from the end of the glacier increased. The average annual velocity of the entire glacier was 0.4-0.6 m day^-1. No correlation between glacier flow velocity and precipitation is denoted. The extent of flowing area was different depending on the season. In addition, we determined the equilibrium line altitude (ELA) from the temperature and precipitation. The accumulation/ablation zones were determined from the estimated ELA. The flow-rate difference between the two glaciers is caused by the ratio between the accumulation zone and the flow velocity, the area ratio of the accumulation zone per unit distance of the ELA. We conclude that the glaciers flow velocity is related to seasonality, ELA, accumulation and ablation zones of the glaciers. We need more multiple indicators, long-term data, the other glacier data, to conduct further research on the relationship between climate change and velocity.