摘要:基于美国冰雪资料中心（NSIDC）提供的卫星遥感雪水当量资料，评估了26个CMIP5（Coupled ModelInter-comparison Project）耦合模式对1981~2005年欧亚大陆冬季雪水当量的模拟能力，在此基础上应用多模式集合平均结果，预估了21世纪欧亚大陆雪水当量的变化情况。结果表明，CMIP5耦合模式对欧亚大陆冬季雪水当量空间分布具有一定的模拟能力，能够再现出欧亚大陆冬季雪水当量由南向北递增、青藏高原积雪多于同纬度其他地区的特征；就雪水当量的幅值而言，几乎所有模式均显著低估了西伯利亚中部雪水当量的大值中心，对中国东北地区雪水当量的模拟也显著偏低，但模式对乌拉尔山以西的东欧平原、我国北方及蒙古地区冬季雪水当量的模拟却比卫星遥感资料显著偏大，此外模式对堪察加半岛及以北的西伯利亚东北部地区的雪水当量也明显偏大。对于青藏高原地区，虽然部分模式可以模拟出青藏高原东部的雪水当量大值区，但大多数模式对青藏高原西部雪水当量的模拟却明显偏大，存在虚假的大值中心。对遥感反演资料的EOF（Empirical Orthogonal Function）分解表明，对于EOF第一个模态所对应欧亚大陆全区一致的年代际变化特征，仅有少数模式具有一定的模拟能力，大多数模式以及多模式集合的结果均未能予以反映；对应于欧亚大陆雪水当量年际变化的EOF第二模态而言，仅有少数模式（如俄罗斯的INMCM4）具有一定的再现能力，绝大多数模式对该模态及其时间演变的特征没有模拟能力。比较CMIP5多模式的集合预估结果与1981~2005年基准时段的雪水当量，可以发现在RCP4.5排放情景下，西伯利亚中东部地区的雪水当量相对于基准时段显著增加，区域平均的增加量在21世纪前、中、后期分别为4.1mm、5.4 mm和6.8 mm，且随时间增加得更显著；对90°E以西的欧洲大陆和青藏高原地区，其雪水当量则相对减少，减少的幅度和显著性也随时间而增大。就雪水当量的相对变化而言，在欧亚大陆东北部存在雪水当量相对变化的大值区，在21世纪后期相对变化显著区大都在5%~10%；但在青藏高原、斯堪的纳维亚半岛进和东欧平原，并没有发现雪水当量相对变化的髙值区，这是由于这些区域冬季雪水当量的幅值较大的缘故。RCP8.5情景下欧亚大陆雪水当量的变化特征与RCP4.5相类似，只是变化的幅度更大。
关键词:CMIP5模式/
雪水当量/
模式评估/
气候预估
Abstract:Based on the remote sensing data from National Snow and ICE Data Center (NSIDC), the performance of CMIP5 (Coupled Model Inter-comparison Project) models in reproducing the winter snow water equivalent (SWE) in the Eurasian continent during 1981-2005 was evaluated first, and the multi-model ensemble (MME) technique was then applied to project the SWE changes over Eurasian continent in the 21st century under the conditions of two different representative concentration pathways (RCP4.5 and RCP8.5) using eight good CMIP models out of total 26 models. The results show that the models were able to reproduce the spatial pattern of winter mean SWE in the Eurasia, i.e. the 25-year average of SWE increased from south to north and SWE in the Tibetan Plateau was much higher than those in other regions of the same latitude. However, some errors still existed in the models. For example, almost all models underestimated the maximum SWE in central Siberia, and SWE in northeastern China was also underestimated. It was found that SWE to the west of Ural Mountains and over northern part of China and Mongolia was overestimated when compared with observation. Meanwhile, only a subset of the models could produce the maximum SWE on the eastern Tibetan Plateau, and the spurious maximum SWE could be found on the western Tibetan Plateau in most CMIP5 models. The spatial and temporal characteristics of winter SWE from CMIP5 model simulations and observations were further analyzed using the Empirical Orthogonal Function (EOF) analysis, and the results suggested that only a small number of CMIP5 models could reproduce main features of the first eigenvector that reflects the decadal variation of SWE over the whole Eurasia. The second mode reflects the annual variation of SWE over the Eurasia, and only a few models (e.g., INMCM4) could reproduce the spatial and temporal characteristics of the second mode to some extent. With respect to the reference period 1981-2005, projection of SWE by the MME under the RCP4.5 shows that SWE in the northeastern Eurasia continent would increase significantly with an increase of 4.1 mm for the 25-year averaged winter SWE in the early stage of the 21st century, followed by 5.4-mm and 6.8-mm increases in the middle and late 21st century, respectively. In contrast, there would exist a decrease of SWE in continental Europe to the west of 90°E and over the Tibetan Plateau and the decrease would become more severe with time. In terms of percentage change of SWE, the region with large magnitudes was found in the northeastern Eurasian continent, where the increase of SWE could be around 5%-10%. However, no maximum centers were found in the Tibetan Plateau, Scandinavian Peninsula and East European Plain possibly because of the large values of winter SWE in these regions. Projection of SWE changes by the MME under the high emission scenario RCP8.5 shows a similar pattern with results under the emission scenario RCP4.5, but with larger amplitudes of changes in snow water equivalence.
Key words:CMIP5 models/
Snow water equivalent/
Model evaluation/
Climate projection
PDF全文下载地址:
http://www.iapjournals.ac.cn/qhhj/article/exportPdf?id=20170301
