Surface Mass Balance of the Antarctic Ice Sheet and its link with surface temperature change in model simulations and reconstructions
Surface Mass Balance of the Antarctic Ice Sheet and its link with surface temperature change in model simulations and reconstructions
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DOI：
10.5194/tc-2019-111
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
Q. Dalaiden;H. Goosse;F. Klein;J. Lenaerts;M. Holloway;L. Sime;E. Thomas
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文献类型：
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作者：
Q. Dalaiden;H. Goosse;F. Klein;J. Lenaerts;M. Holloway;L. Sime;E. Thomas
抽象的。提高我们对南极冰盖(AIS)表面质量平衡(SMB)时空变异性的认识，对于减少过去、现在和未来南极对海平面上升的影响的不确定性至关重要。在这里，我们表明，全球气候模式(GCM)可以再现当今(1979-2005年)AIS SMB以及过去两个世纪的时间变化。在模型模拟中对表面温度-SMB关系的研究表明，两者之间有很强的联系。基于冰芯的重建显示出较弱的关系，表明模型与数据的差异可能是由于模型偏差或记录中存在的非气候噪声造成的。我们发现，在区域尺度上，模拟的温度-SMB关系强于δ-18O-温度之间的关系。这表明SMB数据可以用来重建过去的表面温度。利用这一发现，我们将同位素使能模式SMB和δ18O的输出与冰芯观测同化，以产生新的地表温度重建。尽管由于观测时间序列短，很难对这一技能进行独立评估，但这种新的重建方法优于以前仅基于δ18O的大陆平均温度重建方法，其与观测表面温度(1958年至2010年CE)的线性相关系数为0.73.东南极地区的改善最大，那里的不确定性特别大。最后，我们提供了过去两个世纪以来AIS的中小企业空间重建显示：1)中小企业趋势在区域尺度上有很大的变异性；2)在1957年至2000年期间，西南极的中小企业大幅增加(0.82GT年−2)，而与此同时，东南极经历了中小企业的大幅减少(−3.3GT年−2)，这与最近的重建结果是一致的。
Abstract. Improving our knowledge of the temporal and spatial variability of the Antarctic Ice Sheet (AIS) Surface Mass Balance (SMB) is crucial to reduce the uncertainties of past, present and future Antarctic contributions to sea level rise. Here, we show that Global Climate Models (GCMs) can reproduce the present-day (1979–2005) AIS SMB and the temporal variations over the last two centuries. An examination of the surface temperature–SMB relationship in model simulations demonstrates a strong link between the two. Reconstructions based on ice cores display a weaker relationship, indicating a model-data discrepancy that may be due to model biases or to the non-climatic noise present in the records. We find that, on the regional scale, the modelled temperature-SMB relationship is stronger than the relationship between δ18O-temperature. This suggests that SMB data can be used to reconstruct past surface temperatures. Using this finding, we assimilate isotope-enabled model SMB and δ18O output with ice-core observations, to generate a new surface temperature reconstruction. Although an independent evaluation of the skill is difficult because of the short observational time series, this new reconstruction outperforms the previous reconstructions for the continental-mean temperature that were based on δ18O alone with a linear correlation coefficient with the observed surface temperatures (1958–2010 CE) of 0.73. The improvement is largest for the East Antarctic region, where the uncertainties are particularly large. Finally, we provide a spatial SMB reconstruction of the AIS over the last two centuries showing 1) large variability in SMB trends at regional scale; and 2) a large SMB increase (0.82 Gt year−2) in West Antarctica over 1957–2000 while at the same time, East Antarctica has experienced a large SMB decrease (−3.3 Gt year−2), which is consistent with a recent reconstruction.