DOI: 10.5194/tc-8-607-2014
Scopus记录号: 2-s2.0-84898627148
论文题名: Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area
作者: Zwinger T ; , Schäfer M ; , Martín C ; , Moore J ; C
刊名: Cryosphere
ISSN: 19940416
出版年: 2014
卷: 8, 期: 2 起始页码: 607
结束页码: 621
语种: 英语
英文关键词: ablation
; age
; anisotropy
; cryosphere
; glacial history
; glacier dynamics
; heat flux
; ice flow
; Last Glacial Maximum
; paleoclimate
; surface temperature
; thermomechanics
; velocity profile
; Antarctica
; East Antarctica
; Queen Maud Land
; Scharffenbergbotnen Valley
英文摘要: We use a full-Stokes thermo-mechanically coupled ice-flow model to study the dynamics of the glacier inside Scharffenbergbotnen valley, Dronning Maud Land, Antarctica. The domain encompasses a high accumulation rate region and, downstream, a sublimation-dominated bare ice ablation area. The ablation ice area is notable for having old ice at its surface since the vertical velocity is upwards, and horizontal velocities are almost stagnant there. We compare the model simulation with field observations of velocities and the age distribution of the surface ice. No satisfactory match using an isotropic flow law could be found because of too high vertical velocities and much too high horizontal ones in simulations despite varying enhancement factor, geothermal heat flux and surface temperatures over large ranges. However, the existence of a pronounced ice fabric may explain the observed present-day surface velocity and mass balance distribution in the inner Scharffenbergbotnen blue ice area. Near absence of data on the temporal evolution of Scharffenbergbotnen since the Late Glacial Maximum necessitates exploration of the impact of anisotropy using prescribed ice fabrics: isotropic, single maximum, and linear variation with depth, in both two-dimensional and three-dimensional flow models. The realistic velocity field simulated with a noncollinear orthotropic flow law, however, produced surface ages in significant disagreement with the few reliable age measurements and suggests that the age field is not in a steady state and that the present distribution is a result of a flow reorganization at about 15 000 yr BP. In order to fully understand the surface age distribution, a transient simulation starting from the Late Glacial Maximum including the correct initial conditions for geometry, age, fabric and temperature distribution would be needed. This is the first time that the importance of anisotropy has been demonstrated in the ice dynamics of a blue ice area and demonstrates the need to understand ice flow in order to better interpret archives of ancient ice for paleoclimate research. © 2014 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/74866
Appears in Collections: 影响、适应和脆弱性 气候变化与战略
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作者单位: CSC, IT Center for Science Ltd., Espoo, Finland; Arctic Centre, University of Lapland, Rovaniemi, Finland; Finnish Meteorological Institute, Helsinki, Finland; British Antarctic Survey, Cambridge, United Kingdom; College of Global Change and Earth System Science, Beijing Normal University, Beijing, China; Department of Earth Sciences, Program for Air, Water and Landscape Sciences, Uppsala University, Uppsala, Sweden
Recommended Citation:
Zwinger T,, Schäfer M,, Martín C,et al. Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area[J]. Cryosphere,2014-01-01,8(2)