Evolving patterns of sterodynamic sea-level rise under mitigation scenarios and insights from linear system theory
Evolving patterns of sterodynamic sea-level rise under mitigation scenarios and insights from linear system theory
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DOI：
10.1007/s00382-021-05727-7
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发表时间：
2021-04
期刊：
影响因子：
4.6
通讯作者：
Quran Wu;Xuebin Zhang;J. Church;Jianyu Hu;J. Gregory
中科院分区：
文献类型：
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作者：
Quran Wu;Xuebin Zhang;J. Church;Jianyu Hu;J. Gregory
海平面上升的长期变化是评估气候变化对多世纪时间尺度影响的一个重要因素。在稳定情景RCP4.5下，CMIP 5模式中的体动海平面（SdynSL）和海洋密度变化在辐射强迫（RF）稳定之前和之后的时期（2000-2070 vs. 2100-2300）表现出不同的模式。稳定模式在地理上更均匀，并且比瞬态模式涉及更深的密度变化渗透。在RCP 2.6、4.5和8.5中，SdynSL变化的时空演变可以近似为瞬态和稳定模式的线性组合。具体而言，当RF快速增加时，SdynSL变化由瞬态模式主导，但一旦RF开始稳定，它就越来越受稳定模式的影响。在RF停止增加之后，稳定模式的增长可能会持续几个世纪。SdynSL变化的演变模式也可以近似为线性系统对时间相关边界条件的响应（其特征在于绿色函数）。通过研究SdynSL变化模拟的线性系统模型与不同的估计的绿色的功能，我们发现，气候海洋环流和海洋的动力响应RF发挥作用，在塑造的模式SdynSL变化。线性系统模型在模拟2100年以后的CMIP 5 SdynSL变化时比单变量模式缩放更准确。在RCP2.6和4.5中，稳定模式的出现导致2000-2300年海洋热膨胀效率降低1-10%。
Long-term behaviour of sea-level rise is an important factor in assessing the impact of climate change on multi-century timescales. Under the stabilisation scenario RCP4.5, Sterodynamic Sea-Level (SdynSL) and ocean density change in the CMIP5 models exhibit distinct patterns over the periods before and after Radiative Forcing (RF) stabilisation (2000–2070 vs. 2100–2300). The stabilisation pattern is more geographically uniform and involves deeper penetration of density change than the transient pattern. In RCP2.6, 4.5 and 8.5, the spatiotemporal evolution of SdynSL change can be approximated as a linear combination of the transient and stabilisation patterns. Specifically, SdynSL change is dominated by the transient pattern when RF increases rapidly, but it is increasingly affected by the stabilisation pattern once RF starts to stabilise. The growth of the stabilisation pattern could persist for centuries after RF ceases increasing. The evolving patterns of SdynSL change can also be approximated as a linear system's responses (characterised by its Green’s function) to time-dependent boundary conditions. By examining SdynSL change simulated in linear system models with different estimates of Green's functions, we find that both the climatological ocean circulation and the ocean's dynamical response to RF play a role in shaping the patterns of SdynSL change. The linear system model is more accurate than the univariate pattern scaling in emulating the CMIP5 SdynSL change beyond 2100. The emergence of the stabilisation pattern leads to a 1–10% decrease in the ocean's expansion efficiency of heat over 2000–2300 in RCP2.6 and 4.5.