Seasonal variability in Antarctic ice shelf velocities forced by sea surface height variations

IF 4.4 2区地球科学 Q1 GEOGRAPHY, PHYSICAL

Cryosphere Pub Date : 2023-07-04 DOI:10.5194/tc-17-2585-2023

C. Mosbeux, L. Padman, E. Klein, P. Bromirski, H. Fricker

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引用次数: 1

Abstract

Abstract. Antarctica's ice shelves resist the flow of grounded ice towards the ocean through “buttressing” arising from their contact with ice rises, rumples, and lateral margins. Ice shelf thinning and retreat reduce buttressing, leading to increased delivery of mass to the ocean that adds to global sea level. Ice shelf response to large annual cycles in atmospheric and oceanic processes provides opportunities to study the dynamics of both ice shelves and the buttressed grounded ice. Here, we explore whether seasonal variability of sea surface height (SSH) can explain observed seasonal variability of ice velocity. We investigate this hypothesis using several time series of ice velocity from the Ross Ice Shelf (RIS), satellite-based estimates of SSH seaward of the RIS front, ocean models of SSH under and near RIS, and a viscous ice sheet model. The observed annual changes in RIS velocity are of the order of 1–10 m a−1 (roughly 1 % of mean flow). The ice sheet model, forced by the observed and modelled range of SSH of about 10 cm, reproduces the observed velocity changes when sufficiently large basal drag changes near the grounding line are parameterised. The model response is dominated by grounding line migration but with a significant contribution from SSH-induced tilt of the ice shelf. We expect that climate-driven changes in the seasonal cycles of winds and upper-ocean summer warming will modify the seasonal response of ice shelves to SSH and that nonlinear responses of the ice sheet will affect the longer trend in ice sheet response and its potential sea-level rise contribution.

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海面高度变化导致的南极冰架速度的季节变化

摘要南极洲的冰架通过与冰隆、褶皱和侧缘接触产生的“支撑”来抵抗搁浅的冰向海洋的流动。冰架变薄和退缩减少了吸引力，导致向海洋输送的质量增加，从而增加了全球海平面。冰架对大气和海洋过程中大的年周期的响应为研究冰架和支撑搁浅冰的动力学提供了机会。在这里，我们探讨了海面高度的季节变化是否可以解释观测到的冰速的季节变化。我们使用来自罗斯冰架（RIS）的几个冰速时间序列、基于卫星的RIS锋面SSH向海估计、RIS下和附近的SH海洋模型以及粘性冰盖模型来研究这一假设。观测到的RIS速度的年变化约为1-10 m a−1（大约1 % 曼流）。冰盖模型，由观测和建模的SSH范围约为10 cm再现了当接地线附近足够大的基础阻力变化被参数化时观察到的速度变化。模型响应主要由接地线迁移引起，但SSH引起的冰架倾斜对模型响应有显著影响。我们预计，气候驱动的风的季节性周期变化和上层海洋夏季变暖将改变冰架对SSH的季节性响应，而冰盖的非线性响应将影响冰盖响应的长期趋势及其潜在的海平面上升贡献。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Cryosphere GEOGRAPHY, PHYSICAL-GEOSCIENCES, MULTIDISCIPLINARY

CiteScore

8.70

自引率

17.30%

发文量

240

审稿时长

4-8 weeks

期刊介绍： The Cryosphere (TC) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on all aspects of frozen water and ground on Earth and on other planetary bodies. The main subject areas are the following: ice sheets and glaciers; planetary ice bodies; permafrost and seasonally frozen ground; seasonal snow cover; sea ice; river and lake ice; remote sensing, numerical modelling, in situ and laboratory studies of the above and including studies of the interaction of the cryosphere with the rest of the climate system.