3:45 PM - 4:00 PM
[ACC26-07] Numerical modeling of future and past fluctuations of Qaanaaq Glacier, northwestern Greenland
Keywords:Greenland , glacier, numerical modeling
Glaciers and ice caps surrounding Greenland is rapidly losing mass. To investigate glacier mass loss and driving mechanisms, we have performed field measurements of ice velocity, surface mass balance and surface elevation at Qaanaaq Glacier, northwestern Greenland for 11 years since 2012. In this study, we developed a numerical model of Qaanaaq Glacier based on the field data. The model experiments were carried out to reproduce past glacier change from 1985 to present and future evolution until 2100.
Qaanaaq Glacier is an outlet glacier of the Qaanaaq ice cap (77°28'N, 69°13'W) situated in northwestern Greenland. From 2012 to 2023, ice velocity and surface mass balance were measured at six locations on the glacier at altitudes from 243 to 968 m a.s.l.. In 2012, 2019, and 2022, surface elevation along the central flowline of the glacier were measured. Bed elevation was surveyed by a radar echo sounding in 2012 and 2022. Based on these observational data, we developed a glacier model to compute the evolution of surface elevation along the central flowline. This model calculates surface elevation and terminus position by using ice velocity and surface mass balance, which were computed by numerical models constructed based on in-situ data. Reanalysis datasets which were corrected with surface elevation of the study site were used to calculate surface mass balance. The initial surface geometry of the model was taken from a digital elevation model generated from aerial photographs take in 1985.
The computed surface elevation change from 1985 to 2022 compared well with observational data (RMSE=6.5 m). Surface elevation change was more controlled by surface mass balance, rather than the changes in the emergence velocity. Surface lowering rate from 2000 to 2011 was 29% greater than the average for the entire period. Analysis of surface mass balance and air temperature data revealed that the accelerated surface lowing was caused by increased summer ablation associated with an increase in the positive degree day sum. Future evolution of the glacier was computed until 2100, by forcing the model with two different scenarios of (1) consistent climate change from 1985 to 2022 and (2) the RCP8.5 scenario. The results of the two experiments indicated average elevation changes of −45 m and −48 m for a period 2022–2100, respectively. These rates of surface lowing showed accelerations of 75% and 138% ad compared to the rate from 1985 to 2022.
This study quantifies the mass loss of a glacier in northwestern Greenland by the combination of field data and numerical experiments. In the presentation, we discuss the details of the observations from 2012 to 2023 and modeled glacier changes in the past and future.
Qaanaaq Glacier is an outlet glacier of the Qaanaaq ice cap (77°28'N, 69°13'W) situated in northwestern Greenland. From 2012 to 2023, ice velocity and surface mass balance were measured at six locations on the glacier at altitudes from 243 to 968 m a.s.l.. In 2012, 2019, and 2022, surface elevation along the central flowline of the glacier were measured. Bed elevation was surveyed by a radar echo sounding in 2012 and 2022. Based on these observational data, we developed a glacier model to compute the evolution of surface elevation along the central flowline. This model calculates surface elevation and terminus position by using ice velocity and surface mass balance, which were computed by numerical models constructed based on in-situ data. Reanalysis datasets which were corrected with surface elevation of the study site were used to calculate surface mass balance. The initial surface geometry of the model was taken from a digital elevation model generated from aerial photographs take in 1985.
The computed surface elevation change from 1985 to 2022 compared well with observational data (RMSE=6.5 m). Surface elevation change was more controlled by surface mass balance, rather than the changes in the emergence velocity. Surface lowering rate from 2000 to 2011 was 29% greater than the average for the entire period. Analysis of surface mass balance and air temperature data revealed that the accelerated surface lowing was caused by increased summer ablation associated with an increase in the positive degree day sum. Future evolution of the glacier was computed until 2100, by forcing the model with two different scenarios of (1) consistent climate change from 1985 to 2022 and (2) the RCP8.5 scenario. The results of the two experiments indicated average elevation changes of −45 m and −48 m for a period 2022–2100, respectively. These rates of surface lowing showed accelerations of 75% and 138% ad compared to the rate from 1985 to 2022.
This study quantifies the mass loss of a glacier in northwestern Greenland by the combination of field data and numerical experiments. In the presentation, we discuss the details of the observations from 2012 to 2023 and modeled glacier changes in the past and future.