Future Changes in the Great Plains Low‐Level Jet Governed by Seasonally Dependent Pattern Changes in the North Atlantic Subtropical High. Issue 4 (20th February 2021)

• Record Type: Journal Article
• Authors: Zhou, Wenyu; Leung, L. Ruby; Song, Fengfei; Lu, Jian
• Is Part Of: Geophysical research letters. Volume 48:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-20
• Subjects: Great Plains low‐level jet -- hydroclimate -- North America -- regional climate change -- subtropical high -- westerly jet; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL090356
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: This study investigates the response of the Great Plains low‐level jet (GPLLJ) to global warming based on ensemble projections of the Coupled Model Intercomparison Project Phase 5 and 6. We show that the GPLLJ will intensify and extend northward in spring and autumn but change marginally in summer. This is governed by seasonally dependent pattern changes in the North Atlantic subtropical high (NASH), that are further linked to the poleward shift of the North America westerly jet (NAWJ). In spring and autumn, a substantial poleward NAWJ shift drives anomalous surface high poleward of the NASH and enhances the southerly GPLLJ to its west over the Central US. Among models, the NASH expansion and GPLLJ enhancement are correlated with the poleward NAWJ shift. In summer, the poleward NAWJ shift is weak and acts more northward. The NASH changes manifest a westward extension, which only affects the southerlies over the Gulf of Mexico. Plain Language Summary: The Great Plains low‐level jet (GPLLJ) refers to the climatological southerly wind that blows from the Gulf of Mexico into the Great Plains along the eastern fringe of the Rocky Mountains. It transports the much‐needed moisture into the Central US and affects the climate and weather there. Here, we investigate how the GPLLJ will change in a future warmer climate and what drives the change. We find that the GPLLJ will intensify and extend further northward in spring and autumn but change little in summer. We show that the GPLLJ enhancement is attributed to the poleward shift in the North America westerly jet that leaves imprints on the surface pressure and circulations. Our results clarify the dynamic links among features of regional circulation changes. The recognition of the jet‐shift effect has implications on constraining the projected GPLLJ changes. Key Points: Under global warming, the Great Plains low‐level jet will intensify and extend northward in spring and autumn but change little in summer Such seasonally dependent changes are governed by distinct pattern changes in the North Atlantic subtropical high Tied to the poleward jet shift, the North Atlantic subtropical high expands poleward in spring and autumn but extends westward in summer