DOI: 10.5194/tc-14-811-2020
论文题名: Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter
作者: Gillet-Chaulet F.
刊名: Cryosphere
ISSN: 19940416
出版年: 2020
卷: 14, 期: 3 起始页码: 811
结束页码: 832
语种: 英语
英文关键词: grounding line
; ice flow
; ice sheet
; ice thickness
; Kalman filter
; sea ice
; sea level change
; topography
; Antarctic Ice Sheet
; Antarctica
英文摘要: Marine-based sectors of the Antarctic Ice Sheet are increasingly contributing to sea level rise. The basal conditions exert an important control on the ice dynamics and can be propitious to instabilities in the grounding line position. Because the force balance is non-inertial, most ice flow models are now equipped with time-independent inverse methods to constrain the basal conditions from observed surface velocities. However, transient simulations starting from this initial state usually suffer from inconsistencies and are not able to reproduce observed trends. Here, using a synthetic flow line experiment, we assess the performance of an ensemble Kalman filter for the assimilation of transient observations of surface elevation and velocities in a marine ice sheet model. The model solves the shallow shelf equation for the force balance and the continuity equation for ice thickness evolution. The position of the grounding line is determined by the floatation criterion. The filter analysis estimates both the state of the model, represented by the surface elevation, and the basal conditions, with the simultaneous inversion of the basal friction and topography. The idealised experiment reproduces a marine ice sheet that is in the early stage of an unstable retreat. Using observation frequencies and uncertainties consistent with current observing systems, we find that the filter allows the accurate recovery of both the basal friction and topography after few assimilation cycles with relatively small ensemble sizes. In addition it is found that assimilating the surface observations has a positive impact on constraining the evolution of the grounding line during the assimilation window. Using the initialised state to perform century-scale forecast simulations, we show that grounding line retreat rates are in agreement with the reference; however remaining uncertainties in the basal conditions may lead to significant delays in the initiation of the unstable retreat. These results are encouraging for the application to real glacial systems. © 2020 BMJ Publishing Group. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164463
Appears in Collections: 气候变化与战略
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作者单位: Univ. Grenoble Alpes, CNRS, IRD, IGE, Grenoble, 38000, France
Recommended Citation:
Gillet-Chaulet F.. Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter[J]. Cryosphere,2020-01-01,14(3)