Distorted Pacific-North American Teleconnection at the Last Glacial Maximum

• Main Authors: Hu, Yongyun, Xia, Yan, Liu, Zhengyu, Wang, Yuchen, Lu, Zhengyao, Wang, Tao
• Format: Text
• Language: English
• Published: 2019
• Subjects: Pacific; Ice Sheet
• Online Access: https://doi.org/10.5194/cp-2019-92; https://www.clim-past-discuss.net/cp-2019-92/

The Pacific-North American (PNA) teleconnection is one of the most important climate modes in the present climate condition, and it enables climate variations in the tropical Pacific to exert significant impacts on North America. Here, we show climate simulations that the PNA teleconnection was largely distorted or broken at the Last Glacial Maximum (LGM). The distorted PNA is caused by a split of the westerly jet stream, which is ultimately forced by the thick and large Laurentide ice sheet at the LGM. Changes in the jet stream greatly alter the extratropical wave guide, distorting wave propagation from the North Pacific to North America. The distorted PNA suggests that climate variability in the tropical Pacific, notably, El Niño and Southern Oscillation (ENSO), would have little direct impact on North American climate at the LGM.