Impact of Winds and Southern Ocean SSTs on Antarctic Sea Ice Trends and Variability
Impact of Winds and Southern Ocean SSTs on Antarctic Sea Ice Trends and Variability
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DOI：
10.1175/jcli-d-20-0386.1
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发表时间：
2021-02-01
影响因子：
4.9
通讯作者：
Ding, Qinghua
中科院分区：
文献类型：
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作者：
Blanchard-Wrigglesworth, Edward;Roach, Lettie A.;Ding, Qinghua
尽管全球变暖，但在卫星观测期间（1979年至今），南极海冰范围（SIE）略有增加。人们已经用多种机制来解释这一趋势，例如风、降水或海洋分层的变化，但尚未达成广泛共识。此外，在历史和人为强迫下运行的完全耦合的地球系统模型通常无法模拟这段时间内的积极的 SIB 趋势。在这项工作中，我们使用在历史和人为强迫下运行的地球系统模型来量化风和南大洋海温对海冰趋势和变化的作用，该模型将极地地区的风和海冰以北的南大洋海温推向1979年至2018年的观测。仅用推风进行的模拟捕获了观测到的SIE年际变化以及从1990年代初以来观测到的长期趋势，但对于他们模拟了 1979 年至 2018 年较长时期的负 SIB 趋势，部分原因是模型中全球和半球规模的变暖速度快于观测到的速度。对微推风和海温的模拟显示，1979 年至 2018 年期间没有显着的 SIE 趋势，与观测结果一致。在区域尺度上，与泛南极尺度相比，模拟海冰在捕捉所有微移模拟中的趋势和年际变化方面表现出更高的技能。我们还发现 1979 年的初始条件对长期趋势的影响可以忽略不计。
Antarctic sea ice extent (SIE) has slightly increased over the satellite observational period (1979 to the present) despite global warming. Several mechanisms have been invoked to explain this trend, such as changes in winds, precipitation, or ocean stratification, yet there is no widespread consensus. Additionally, fully coupled Earth system models run under historic and anthropogenic forcing generally fail to simulate positive SIB trends over this time period. In this work, we quantify the role of winds and Southern Ocean SSTs on sea ice trends and variability with an Earth system model run under historic and anthropogenic forcing that nudges winds over the polar regions and Southern Ocean SSTs north of the sea ice to observations from 1979 to 2018. Simulations with nudged winds alone capture the observed interannual variability in SIE and the observed long-term trends from the early 1990s onward, yet for the longer 1979-2018 period they simulate a negative SIB trend, in part due to faster-than-observed warming at the global and hemispheric scale in the model. Simulations with both nudged winds and SSTs show no significant SIE trends over 1979-2018, in agreement with observations. At the regional scale, simulated sea ice shows higher skill compared to the pan-Antarctic scale both in capturing trends and interannual variability in all nudged simulations. We additionally find negligible impact of the initial conditions in 1979 on long-term trends.