On the relationship between Ural blocking and Arctic-midlatitude thermal
gradient
Abstract
In this study, the relationship between the interannual variability of
Arctic-midlatitude thermal gradient (AMG) and the winter atmospheric
blocking frequency in the Ural region (UBF) is investigated in the ERA5
reanalysis product from 1940 to 2023. In particular, the paper focuses
on the large-scale atmospheric circulation patterns associated with high
UBF concomitant to weak AMG and vice versa, revisiting the more common
and documented relationship connecting intense Ural blocking activity to
strong AMG. Results show that displacements of the atmospheric blocking
from the Ural region towards the Arctic lead to anomalous southerly
thermal advections at polar latitudes and stronger AMG. On the other
hand, high blocking frequency co-occurring in the Ural, Greenland and
Chukotka regions lead to weaker AMG by limiting northward heat
advections towards the Arctic region. These findings highlight a more
complex picture of the role of subpolar atmospheric circulation in
controlling the AMG.