Interdecadal component variation characteristics in heavy winter snow intensity in North-Eastern China and its response to sea surface temperatures

Based on daily precipitation data from 208 weather stations, monthly NCEP/NCAR reanalysis data, and sea surface temperature data reconstructed by NOAA between 1961 and 2012, the heavy winter snow intensity in North-Eastern China was defined; its spatiotemporal variation characteristics were analyzed; the physical mechanisms of the relations between key sea surface temperature (SST) regions and heavy winter snow intensity were studied. Results showed that, in terms of temporal variation characteristics: heavy winter snow intensity in North-Eastern China has been rising, with obvious interdecadal variations during the study interval. In terms of spatial variation characteristics: the first empirical orthogonal function (EOF) mode of the interdecadal component in heavy winter snow intensity showed consistent anomaly characteristics throughout the region; the second mode exhibited opposite variation characteristics between the south and north; and the third mode exhibited opposite variation characteristics between the northwest and southeast. In terms of physical mechanisms underlying the effects of SST on heavy winter snow intensity, the key SST region of the first EOF mode was the Oyashio, the interdecadal component of the autumn Oyashio SST was abnormally high, which corresponded to a higher winter 500 hPa height field in the northern section of the North Pacific. This condition led to a blocking situation and was associated with a weaker East Asian winter monsoon (EAMW), which resulted in a stronger interdecadal component of heavy winter snow intensity and vice versa. The second mode was closely related to the Pacific Decadal Oscillation (PDO): the interdecadal component of the autumn PDO was abnormal, which induced the teleconnection pattern of the winter Pacific-North America (PNA) pattern. The PNA pattern may have been related to the second EOF mode through its association with the Mongolian high.