Mid-Latitude Jet Response to Pan-Arctic and Regional Arctic Warming in Idealized GCM

• Published in: Atmosphere
• Main Authors: Gun-Hwan Yang, Woosok Moon, Hayeon Noh, Baek-Min Kim
• Format: Text
• Language: English
• Published: Multidisciplinary Digital Publishing Institute 2023
• Subjects: Arctic amplification; atmospheric circulation; jet; climate change; idealized model; Arctic; Climate change
• Online Access: https://doi.org/10.3390/atmos14030510

To study the dynamical mechanism by which Arctic amplification affects extreme weather events in mid-latitude, we investigated the local and remote circulation response to pan-Arctic and regional Arctic thermal forcing. A comprehensive atmospheric GCM (General Circulation Model) coupled to a slab mixed-layer ocean model is used for the experiment. With the increasing thermal forcing in the pan-Arctic configuration, the mid-latitude jet tends to shift equatorward, mainly due to the southward shift of the convergence zone of eddy-heat flux and eddy-momentum flux. From the regional Arctic forced experiments, zonal mean response is similar to the response from the pan-Arctic configuration. The non-zonal response is characterized by the 300 hPa circumpolar zonal wind of wavenumber-1 structure, which establishes an enhanced wavier mid-latitude jet. In the polar region at 300 hPa, regional thermal forcing drives a distinct east–west dipole circulation pattern, in which anticyclonic circulation is located to the west of the thermal forcing, and cyclonic circulation is located to the east. The lower-level circulation shows the opposite pattern to the upper-level circulation in the polar region. While the strength of circulation increases with gradual thermal forcing, the overall dipole pattern is unchanged. In regional warming simulation, compared to the pan-Arctic warming, increasing residual heat flux in a dipole pattern causes enhanced heat advection to mid-latitude.