高级检索

冬季东北冷涡多尺度特征及其季节内振荡对东北-华北地区极端低温的影响

The Multiscale Features of Boreal Winter Northeast Cold Vortex and Its Intraseasonal oscillations" Influence on Extreme Low Temperatures in the Northeast-North China Region

  • 摘要: 采用欧洲中期天气预报中心(ECMWF)提供的ERA5逐日再分析数据集,对1979-2020年冬季东北冷涡(Northeast Cold Vortex,NECV)展开客观识别,探讨其生命期、强度、空间分布以及活动日数等气候特征,并定义冷涡指数(Northeast Cold Vortex Index,NECVI)分析冷涡活动多尺度特征,基于该指数使用SVD和回归分析讨论东北冷涡在季节内尺度对我国东北-华北地区(Northeast and North China,NE-N)冬季温度的影响。研究发现,42年间冬季在识别区内( 35°N -60°N,115°E -145°E) 共出现266次东北冷涡活动过程,主要位于识别区的北部(45°N-60°N,115°E-145°E),平均生命期为4.3天;东北冷涡活动没有明显的长期变化趋势和年代际变化特征,但存在明显的年际变化,主要周期为2.2-2.5a;冬季东北冷涡季节内振荡周期以10-40 d为主。SVD和回归结果表明当NE-N地区有大范围低频低温发生时,欧亚大陆自西欧高纬度地区至东北亚上空存在一个纬向“+”、“-”、“+”、“-”、“+”的低频波列,东北地区常伴随有很强的冷涡活动,且NE-N地区低频低温的发生落后于低频东北冷涡3-5d左右。

     

    Abstract: Utilizing the ERA5 daily reanalysis dataset provided by the European Centre for Medium-Range Weather Forecasts (ECMWF), an objective identification is carried out to obtain the Northeast Cold Vortex (NECV) during the winter season from 1979 to 2020 and the life cycle, intensity, spatial distribution, and number of active days of NECV are explored. Furthermore, an Index of Northeast Cold Vortex (NECVI) is defined to analyze the multiscale features of NECV activity. Based on NECVI, Singular Value Decomposition (SVD) and regression analyses were performed to examine the influence of NECV on winter temperatures in Northeast and North China (NE-N) on intraseasonal scale. Results showed that over the 42 years, there were a total of 266 occurrences of NECV activity during the winter season within the identification area (35°N -60°N, 115°E -145°E), mainly located in the northern part of the identification area (45°N-60°N, 115°E-145°E), with an average life cycle of 4.3 days. The NECV activity does not show a significant linear trend or interdecadal variability, but there is a robust interannual variability with the main period of 2.2-2.5 years, while the intraseasonal oscillation period of the winter NECV is primarily 10-40 days. The SVD and regression analysis indicate that when there is a large-scale low-frequency cold temperature event occurs in the NE-N region, there lies a zonally low-frequency wave train with alternating positive and negative centers from the high-latitude areas of Western Europe to Northeast Asia, meanwhile, the Northeast region is often accompanied by strong cold vortex activity, and the occurrence of low-frequency cold temperatures in the NE-N region lags the low-frequency NECV by about 3-5 days.

     

/

返回文章
返回