Page 61 - 《高原气象》2022年第6期

高 原 气 象 41 卷
1424

Low-Frequency Characteristics of Large-Scale Persistent Low

Temperature Events in Winter in China and its Relation to
Atmospheric Low-frequency Oscillation

1
TAN Ying ，LI Liping ，SHI Chunhua ，MAO Weiyi ，LI Yige 3，1
1
2
1
（1. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of
Meteorological Disaster（NUIST），Ministry of Education，Nanjing University of Information
Science &Technology，Nanjing 210044，Jiangsu，China；
2. Institute of Desert Meteorology，China Meteorological Administration，Urumqi 830002，Xinjiang，China；
3. Xiyang County Meteorological Bureau，Xiyang 045300，Shanxi，China）

Abstract：Based on the daily air temperature data from more than 2000 stations by the National Meteorological
Information Center and NCEP/NCAR daily reanalysis data from 1980 to 2017，the effects of low-frequency oscil‐
lation on three types（nationwide，northeastern and eastern）of large-scale persistent low temperature events
（short for events）in winter over China are compared and studied. The results show that there are more events
since the 1980s to the early 1990s and the 2000s，and the winter temperature has a significant period of 10~30
days. By analyzing the atmospheric circulation field，it is found that the low-frequency Siberian high（SH）is the
main influence system of the three types of events in the lower level. The low-frequency Siberian high is the
strongest in the national type events，and the weakest in the northeast type events. The range of the Siberian high
is the largest in the national type events，with its southern boundary can reach the south of the Yangtze River，
and it is tilted to east in both the northeast and east type events. In addition，the low-frequency Aleutian low
（AL）to the west is also one of the main low-frequency systems affecting the northeast type events. In the middle
troposphere，both the national and east type events have the process of the low-frequency transverse trough turn‐
ing vertically and merging with the East Asian trough，and the transverse trough has a larger zonal scale in the na‐
tional type events，while the northeast type events are mainly affected by the northeast cold vortex. In the upper
troposphere，we can find that the temperate jet stream as a whole continued to be weak and the subtropical jet
stream as a whole continued to be strong in the national type events. Temperate jet stream is strong in the west
and weak in the east，while the subtropical jet stream is weak in the west and strong in the east in the northeast
type events. The temperate jet stream in the eastern type events continue to be weak，but the degree of weakness
is greater than that of the national type events，and the subtropical jet stream is strong in the west and weak in the
east. In addition，the western forecast signals of -12 days（national type），-9 days（northeast type）and -10 days
（eastern type）and the eastern signal of -12 days（national type）at low-frequency 500 hPa height field should be
paid attention to respectively.
Key words：Persistent low temperature events；Chinese winter；atmospheric low-frequency oscillation；extend‐
ed-range forecast