Future Change of Northern Hemisphere Summer Tropical-Extratropical Teleconnection in CMIP5 Models*
Future Change of Northern Hemisphere Summer Tropical-Extratropical Teleconnection in CMIP5 Models*
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DOI：
10.1175/jcli-d-13-00261.1
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发表时间：
2014-05-01
影响因子：
4.9
通讯作者：
Ha, Kyung-Ja
中科院分区：
文献类型：
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作者：
Lee, June-Yi;Wang, Bin;Ha, Kyung-Ja
北半球夏季(6-8月)温带温带的两种主要的全球尺度遥相关已经被确定：北太平洋西部-北美(WPNA)和环全球遥相关(CGT)型。这些遥相关型对NH夏季季节气候预报具有重要意义。本文利用典型浓度路径4.5(RCP4.5)实验，通过参与CMIP5阶段5的20个耦合模式，研究了这些遥相关在人为全球变暖下的变化。根据它们在模拟两种遥相关型以及大气环流、降水和海温的气候学手段和变化方面的表现，选出了6个最佳模式。选定的模式相当好地捕捉到了CGT及其与印度夏季风(ISM)的关系。这些模式也能捕捉到WPNA环流型，但由于对西北太平洋夏季风降水的模拟不佳，在再现其相关的降水异常方面存在明显的不足。在RCP4.5情景下，预计21世纪后半叶将发生以下变化：1)由于大气稳定性增强，高层环流的年际变率显著减弱，尽管热带对流加热的适度增加可能会增强这种变异性；2)WPNA模式和主要谱峰加强，特别是在东太平洋-北美和北大西洋-欧洲部分，这归因于它与前一个成熟的厄尔尼诺-南方涛动(ENSO)阶段的关系加强；(3)大气稳定化使CGT减弱，与ISM的关系减弱，ISM-ENSO关系减弱。
Two dominant global-scale teleconnections in the Northern Hemisphere (NH) extratropics during boreal summer season (June-August) have been identified: the western North Pacific-North America (WPNA) and circumglobal teleconnection (CGT) patterns. These teleconnection patterns are of critical importance for the NH summer seasonal climate prediction. Here, how these teleconnections will change under anthropogenic global warming is investigated using representative concentration pathway 4.5 (RCP4.5) experiments by 20 coupled models that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5). The six best models are selected based on their performance in simulation of the two teleconnection patterns and climatological means and variances of atmospheric circulation, precipitation, and sea surface temperature. The selected models capture the CGT and its relationship with the Indian summer monsoon (ISM) reasonably well. The models can also capture the WPNA circulation pattern but with striking deficiencies in reproducing its associated rainfall anomalies due to poor simulation of the western North Pacific summer monsoon rainfall. The following changes are anticipated in the latter half of twenty-first century under the RCP4.5 scenario: 1) significant weakening of year-to-year variability of the upper-level circulation due to increased atmospheric stability, although the moderate increase in convective heating over the tropics may act to strengthen the variability; 2) intensification of the WPNA pattern and major spectral peaks, particularly over the eastern Pacific-North America and North Atlantic-Europe sectors, which is attributed to the strengthening of its relationship with the preceding mature phase of El Nino-Southern Oscillation (ENSO); and 3) weakening of the CGT due to atmospheric stabilization and decreasing relationship with ISM as well as weakening of the ISM-ENSO relationship.