Effect of prescribed sea surface conditions on the modern and future Antarctic surface climate simulated by the ARPEGE atmosphere general circulation model
Effect of prescribed sea surface conditions on the modern and future Antarctic surface climate simulated by the ARPEGE atmosphere general circulation model
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ARPEGE大气环流模型模拟的规定海面条件对现代和未来南极表面气候的影响
DOI：
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
A. Alias
中科院分区：
文献类型：
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作者：
J. Beaumet;M. Déqué;G. Krinner;Cécile Agosta;A. Alias
摘要。由于降雪增加，预计到本世纪末，南极冰盖表面物质平衡将增加。假设没有冰动力的相关响应，这将是海平面上升的负贡献。然而，利用耦合气候模式预估的动态降尺度对这些变化的评估仍然具有相当大的不确定性，这是由于高纬度大气环流和海表条件（即海面温度和海冰浓度）的代表性不足。本研究评估了利用全球高分辨率大气模式模拟的南极地表气候，并评估了由两个耦合气候模式预估获得的两个不同SSC数据集对模拟南极地表气候的影响。两个耦合模式，即mic - esm和NorESM1-M，在CMIP5 RCP8.5预估范围的两端模拟了未来南极海冰趋势。为了达到南极洲上空35公里的平均水平分辨率，采用了一种伸展网格结构的大气模式ARPEGE。在1981-2010年期间，ARPEGE是由来自microc - esm、NorESM1-M和CMIP5历史运行的ssc和观测到的ssc驱动的。对这三个模拟进行了大气环流的ERA-Interim再分析、MAR区域气候模式和地面气候的现场观测。对于21世纪后期，在RCP8.5排放情景的强迫下，直接使用来自相同耦合气候模式的SSCs，并使用一种异常方法进行偏差校正，该方法包括将耦合模式预估的未来气候异常添加到观测到的SSCs中，并考虑这些异常的分位数分布。我们评估了用偏校正后的SSCs代替原始SSCs驱动大气模式的效果。对于使用NorESM1-M的SSCs进行的模拟，当使用偏差校正的SSCs时，在整个南极洲上空没有发现明显不同的气候变化信号。对于由microc - esm ssc驱动的模拟，当使用偏差校正的ssc时，南极冰盖的降水和冬季温度显著增加。对于发现的南极变暖范围（+3至+4 K），我们确认降雪量的增加将在很大程度上超过融雪和降雨的增加。利用CMIP5 RCP8.5预估的海冰趋势端元，得到的变暖差异（~ 1 K）远小于CMIP5南极变暖预估的范围。这证实，在气候模式中表示南半球大气环流的误差也是预测21世纪后期南极气候变化多样性的决定因素。
Abstract. Owing to increase in snowfall, the Antarctic Ice Sheet surface mass balance is expected to increase by the end of the current century. Assuming no associated response of ice dynamics, this will be a negative contribution to sea-level rise. However, the assessment of these changes using dynamical downscaling of coupled climate model projections still bears considerable uncertainties due to poorly represented high-southern-latitude atmospheric circulation and sea surface conditions (SSCs), that is sea surface temperature and sea ice concentration. This study evaluates the Antarctic surface climate simulated using a global high-resolution atmospheric model and assesses the effects on the simulated Antarctic surface climate of two different SSC data sets obtained from two coupled climate model projections. The two coupled models from which SSCs are taken, MIROC-ESM and NorESM1-M, simulate future Antarctic sea ice trends at the opposite ends of the CMIP5 RCP8.5 projection range. The atmospheric model ARPEGE is used with a stretched grid configuration in order to achieve an average horizontal resolution of 35 km over Antarctica. Over the 1981–2010 period, ARPEGE is driven by the SSCs from MIROC-ESM, NorESM1-M and CMIP5 historical runs and by observed SSCs. These three simulations are evaluated against the ERA-Interim reanalyses for atmospheric general circulation as well as the MAR regional climate model and in situ observations for surface climate. For the late 21st century, SSCs from the same coupled climate models forced by the RCP8.5 emission scenario are used both directly and bias-corrected with an anomaly method which consists in adding the future climate anomaly from coupled model projections to the observed SSCs with taking into account the quantile distribution of these anomalies. We evaluate the effects of driving the atmospheric model by the bias-corrected instead of the original SSCs. For the simulation using SSCs from NorESM1-M, no significantly different climate change signals over Antarctica as a whole are found when bias-corrected SSCs are used. For the simulation driven by MIROC-ESM SSCs, a significant additional increase in precipitation and in winter temperatures for the Antarctic Ice Sheet is obtained when using bias-corrected SSCs. For the range of Antarctic warming found ( +3 to +4 K), we confirm that snowfall increase will largely outweigh increases in melt and rainfall. Using the end members of sea ice trends from the CMIP5 RCP8.5 projections, the difference in warming obtained ( ∼ 1 K) is much smaller than the spread of the CMIP5 Antarctic warming projections. This confirms that the errors in representing the Southern Hemisphere atmospheric circulation in climate models are also determinant for the diversity of their projected late 21st century Antarctic climate change.
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