Orbital Forcing Strongly Influences the Poleward Shift of the Spring Himalayan Jet During the Past Millennium
Orbital Forcing Strongly Influences the Poleward Shift of the Spring Himalayan Jet During the Past Millennium
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DOI：
10.1029/2021gl095955
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发表时间：
2021-09
影响因子：
5.2
通讯作者：
U. Thapa;S. Stevenson;M. Midhun
中科院分区：
文献类型：
--
作者：
U. Thapa;S. Stevenson;M. Midhun
喜马拉雅副热带急流的纬度位置（喜马拉雅急流纬度或HJL）通过引导水汽输送风暴来控制该地区冬季和春季的气候。在这里，我们使用群落地球系统模型—上一千年集合来诊断过去一千年HJL的强迫趋势。850—1849年冬季HJL有较弱的偏赤道趋势。而春季HJL的向极趋势相对较大，向极/赤道漂移的方差和频率均有所增加。我们发现，轨道岁差的变化降低了热带和亚热带亚洲之间的热梯度，使春季HJL向极地移动。在1850-2005年期间，由于轨道强迫和人为温室气体强迫的补偿影响，春季HJL没有表现出趋势。这些发现表明，气候模式正确模拟轨道强迫和人为因素之间的影响和潜在的相互作用对于准确预测喜马拉雅急流的变率和相关的风暴路径至关重要。
The latitudinal position of the subtropical jet over the Himalayas (Himalayan jet latitude or HJL) controls the region's climate during winter and spring by guiding moisture‐delivering storms. Here we use the Community Earth System Model‐Last Millennium Ensemble to diagnose forced trends in HJL during the past millennium. During 850–1849, there is a weak equatorward trend in winter HJL. In contrast, the spring HJL has a relatively larger poleward trend, and increases in both variance and frequency of poleward/equatorward excursions. We demonstrate changes in orbital precession reduced the thermal gradient between tropical and subtropical Asia, shifting the spring HJL poleward. During 1850–2005, the spring HJL exhibits no trend due to compensating influences from orbital and anthropogenic greenhouse gas forcings. These findings suggest it is essential climate models properly simulate the effects of and potential interactions between orbital forcing and anthropogenic factors to accurately project Himalayan jet variability and associated storm tracks.