On the cooccurrence of wintertime temperature anomalies over eastern Asia and eastern North America

The cooccurrence of wintertime temperature anomalies over eastern Asia and eastern North America is examined. The winter days during 1948-2014 are assigned to nine regimes by applying the self-organizing map clustering method to the area-averaged land surface temperature anomalies over these two regions. About half of the winter days are associated with concurrent temperature anomalies. The occurrence of the concurrent/nonconcurrent regimes is closely related to the large-scale circulation conditions. The Eurasian teleconnection pattern and the Pacific-North American teleconnection pattern are two dominant large-scale circulation modes associated with the cooccurrence of the temperature anomalies, through their impacts on the intensities of the corresponding troughs. The precursor analysis reveals that the lead time of the early signals for the concurrent cold anomalies is about 4 days longer than that for the concurrent warm anomalies. In addition, the average lead time of the precursor signals for the wintertime temperature anomalies over eastern Asia is longer than that over eastern North America.