Many tropospheric Arctic Oscillation (AO) events are preceded by stratospheric AO events and even
earlier in time by anomalous upward energy flux associated with Rossby waves in the troposphere. This study
identifies lower-tropospheric circulation anomalies that precede large AO events in both the troposphere and
stratosphere and the anomalous upward energy flux. Compositing analysis of stratospheric warming events
identifies regional tropospheric precursors, which precede stratospheric warmings. The tropospheric precursor
is found to vary when compositing over polar vortex displacements and splits separately. Prior to
vortex displacements the main anomaly sea level pressure center of the tropospheric precursor is located
across northwest Eurasia and is associated with the Siberian high. Prior to vortex splits a similar anomaly
center is identified in the tropospheric precursor but is weaker and appears to be more strongly related to
a shift in the storm tracks. Differences in the sea level pressure anomalies in the North Atlantic and the North
Pacific are also observed when comparing the precursors prior to vortex displacements and splits. Identifi-
cation of a unique tropospheric precursor to stratospheric warming and subsequent tropospheric AO events
can help to improve understanding troposphere–stratosphere coupling. Furthermore, the observational evidence
presented here can be compared with model simulations of winter climate variability and lead to
potential model improvements.