A strong coherence of the summer (June–August) surface air temperature (SAT) anomalies exists over the eastern Eurasia (EE) and the central Eurasia (CE) in association with a remarkable intraseasonal (10-90-day) variability. The intraseasonal SAT seesaw over Eurasia shows a negative correlation between EE and CE, which is closely related to an intraseasonal wave train at the upper troposphere over the mid-high latitudes of Eurasia. The wave train propagates eastward and results in the intraseasonal variation of air temperature in a seesaw pattern. The column-integrated temperature budget suggests that vertical adiabatic advection plays a dominant role in causing the dipole SAT anomalies. The propagation of the Rossby wave train at upper troposphere helps to maintain the circulation anomalies associated with the dipole SAT. The leading modes of meridional wind anomalies at 200 hPa over the Eurasian high latitudes resemble the intraseasonal wave train, indicating that the wave train associated with the dipole SAT seesaw is an atmospheric intrinsic mode over the mid-high latitudes. This study also investigates the impact of the intraseasonal SAT seesaw on regional heat wave events. It is suggested that the intraseasonal SAT seesaw has a major influence on the variability of heat wave events over both EE and CE, which may provide great implications for regional sub-seasonal forecast of extreme weather events.

intraseasonal oscillation,heat wave,wave train