17:15 〜 19:15
[ACC32-P08] 高解像度解析を用いた南極棚氷における標高勾配と流動変動のフィルン厚への影響評価
キーワード：南極、棚氷、フィルン厚、フィルンモデル、ダウンスケーリング
Antarctic ice shelves, floating extension of land ice, cover over 1,516 million km2, a size comparable to the Greenland Ice sheet. They extend along 75% of Antarctica’s coastline and account for approximately 11% of the Antarctic Ice Sheet (Rignot et al., 2013). As grounded ice crosses the boundary, 74% transitions into the ice shelf or outlet glaciers (Bindschandler et al., 2011). Ice shelves play a crucial role in stabilizing grounded ice through buttressing. Additionally, the firn layer on ice shelves acts as a buffer, retaining meltwater; however, increasing melt rates reduce pore space, leading to hydrofracturing (Kuipers Munneke et al., 2014). Previous studies have assessed firn thickness using regional atmospheric climate models based on the Eulerian framework. However, these methods do not adequately account for fast-moving glaciers, where surface boundary conditions (e.g., surface temperature, accumulation and melt rate) change annually (Figure 1). Furthermore, the coarse resolution of conventional models limits their ability to capture all relevant features accurately. In this study, we apply a Lagrangian framework to quantify firn thickness over the ice shelf of Shirase Glacier in East Antarctica, considering the effects of ice flow and elevation changes. ERA5 reanalysis data is downscaled using a physically based approach to a 500 m resolution and incorporated into the Community Firn Model (Stevens et al., 2020).
Figure 1. Elevation and ice flow profiles along the central flowline of Shirase Glacier. The blue and green circles represent locations that have migrated over a 45-year period due to ice flow.
References
Bindschadler, R., Choi, H., Wichlacz, A., Bingham, R., Bohlander, J., Brunt, K., and 12 others: Getting around Antarctic: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year, The Cryosphere, 5, 569–588, https://doi.org/10.5194/tc-5-569-2011, 2011
Kuipers Munneke, P., Ligtenberg, S. R. M., van den Broeke, M. R., and Vaughan, D. G.: Firn air depletion as a precursor of Antarctic ice-shelf collapse, J. Glaciol., 60, 205–214, 2014
Rignot, E., Jacobs, S., Mouginot, J., and Scheuchl, B.: Ice shelf melting around Antarctica, Science, 341, 266–270, https://doi.org/10.1126/science.1235798, 2013
Stevens, C. M., Verjans, V., Lundin, J. M. D., Kahle, E. C., Horlings, A. N., Horlings, B. I., and Waddington, E. D.: The Community Firn Model (CFM) v1.0, Geosci. Model Dev., 13, 4355–4377, https://doi.org/10.5194/gmd-13-4355-2020, 2020
Figure 1. Elevation and ice flow profiles along the central flowline of Shirase Glacier. The blue and green circles represent locations that have migrated over a 45-year period due to ice flow.
References
Bindschadler, R., Choi, H., Wichlacz, A., Bingham, R., Bohlander, J., Brunt, K., and 12 others: Getting around Antarctic: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year, The Cryosphere, 5, 569–588, https://doi.org/10.5194/tc-5-569-2011, 2011
Kuipers Munneke, P., Ligtenberg, S. R. M., van den Broeke, M. R., and Vaughan, D. G.: Firn air depletion as a precursor of Antarctic ice-shelf collapse, J. Glaciol., 60, 205–214, 2014
Rignot, E., Jacobs, S., Mouginot, J., and Scheuchl, B.: Ice shelf melting around Antarctica, Science, 341, 266–270, https://doi.org/10.1126/science.1235798, 2013
Stevens, C. M., Verjans, V., Lundin, J. M. D., Kahle, E. C., Horlings, A. N., Horlings, B. I., and Waddington, E. D.: The Community Firn Model (CFM) v1.0, Geosci. Model Dev., 13, 4355–4377, https://doi.org/10.5194/gmd-13-4355-2020, 2020