Responses of Amplified Northern Hemisphere Winter Stationary Waves to Asia-Pacific Jet Core Activity under SST Warming
This study uses the Global/Regional Integrated Model system (GRIMs) version 4.0 to examine the dynamic processes related to the recent strengthening of winter stationary waves across western North America and the potential contribution of the northward shift of westerly jet stream under global warming. We found that global SST warming contributed to the northward shift and intensification of the Asia-Pacific jet core, resulting in a pronounced ridge formed over western North America and an amplification of winter stationary waves in mid-latitudes. However, when SST warming is confined only to the tropics, a less prominent ridge is observed, and extended warming periods can push the jet core southwards, creating an environment less favorable for stationary wave formation. These robust stationary waves significantly reshape the atmospheric circulation in western North America, causing wetter conditions near the Pacific Northwest and drier condition in the Southwest. These findings shed light on the large-scale atmospheric circulation changes triggered by SST warming and provide valuable insights into predicting mid-latitude hydroclimate extremes.