Gaoyuan qixiang (Jun 2023)
Synergistic Effects of Mid-Latitude Sea Surface Temperature on Intensity Anomalies of Cold Waves in Winter of Northern China
Abstract
Based on the daily minimum temperature data from 1980 to 2019 from the National Meteorological Information Center （China）， the monthly NCEP/NCAR reanalysis data and sea surface temperature （SST） data from Hadley Center （UK）， the spatial-temporal characteristics of the cold wave intensity in winter in northern China are analyzed， and the impact mechanisms of the mid-latitude SST anomalies（SSTA）in the northern hemisphere on it are also investigated.The results show that： （1） There are interannual and interdecadal variations in the cold wave intensity in northern China.Its interdecadal variability is more pronounced before 1998， and interannual variability is greater after 1999.The cold wave is strongest in North China， followed by the junction of Inner Mongolia， Gansu and Xinjiang.（2） The cold wave intensity mainly includes three kinds of anomalous distribution， namely， the regional consistent pattern， the east-west antiphase pattern and the tripolar pattern.The regional consistent pattern can basically reflect the overall spatial-temporal anomaly characteristics of the cold wave intensity.（3） The SSTA like a negative phase Pacific Decadal Oscillation （"-PDO"-like） pattern in the North Pacific from pre-spring to winter and the negative SSTA in the North Atlantic from pre-autumn to winter are conducive to the enhancement of cold wave in northern China.The effects of SSTA on the cold wave intensity in the two oceans in pre-autumn are equivalent， while the impacts of the North Atlantic SSTA are more significant in winter.（4） The "-PDO"-like SSTA in the North Pacific from pre-spring to pre-autumn and negative SSTA in the North Atlantic from pre-autumn to winter can trigger the winter teleconnection pattern or wave train anomalies， such as the negative phase Arctic Oscillation （"-AO"）， positive phase Eurasian Pacific （"+EUP"） teleconnection wave train， Pacific-North America （"PNA"）-like pattern， negative phase North Atlantic Oscillation （"-NAO"）.There is a similar cross-seasonal "relay" relationship between the two oceanic SSTA.In pre-autumn and winter， the interaction of two oceans makes the upstream Rossby wave energy dispersing downstream， and continuously strengthens the "+EUP" teleconnection wave train， resulting in Urals ridge and East Asian trough stronger.Along with the cooperation of 300 hPa jet stream that is weaker in the north and stronger in the south， it will facilitate the southward movement of cold air from high latitude and accumulation in northern China.The coordination of the high-level and low-level circulation leads to an enhancement of the cold wave intensity in northern China.
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