A winter cold nights pattern in the Northern Hemisphere lands: Circum-hemisphere teleconnection of extreme cold events

This study discovers a teleconnection of winter cold nights (TN10p) in the Northern Hemisphere lands, termed as the Circum-hemisphere teleconnection (CHT) of extreme cold events (CHTe). The CHTe exhibits five distinct centers of action situated in the Southeastern North America, Baffin Bay Coast, Northern Europe, Middle East-North Africa, and Eastern Siberia. Notably, it displays significant interannual (similar to 3a) and decadal (similar to 10a) variabilities. Besides, the differences between the CHTe and several known atmospheric and oceanic modes are also illustrated in terms of the occurrence year, physical nature, temporal variability, and spatial structure. Meanwhile, a new atmospheric teleconnection pattern in the troposphere, named as the CHT, corresponds to the atmospheric circulation associated with the CHTe. During the positive CHTe events, the positive CHT events occur, resulting in significant positive geopotential height anomalies (GHTa) over the Central North Atlantic, Western Europe and Songhua River as well as significant negative GHTa over Greenland and Caspian Sea, and vice versa. Compared with the horizontal advections, vertical convections and diabatic heating, the CHT may mainly influence the local TN10p anomalies by modulating atmospheric thickness anomalies over five regions of the CHTe.