大气科学学报2025，Vol.48Issue(1)：37-48,12.DOI:10.13878/j.cnki.dqkxxb.20241001001
北美-东亚冬季极端低温空间复合事件及其与高空急流的联系
Wintertime concurrent cold extremes between North America and East Asia:dynamics and linkage with jet streams variability
摘要
Abstract
In recent decades,the Northern Hemisphere has experienced frequent temperature extremes that have significantly influenced human well-being,socioeconomic stability,and ecological systems.Among these,concurrent cold extremes have concurrently occurred across multiple regions and have drawn increasing attention,often linked to variations in jet stream dynamics.Despite growing interest,most studies have focused on individual events,leaving a limited understanding of the mechanisms driving concurrent temperature extremes across regions.This study focused on the characteristics and possible mechanisms of concurrent cold extremes in East Asia and North America during winter from 1979 to 2021,using the Climate Prediction Center minimum surface air tem-perature dataset and the NCEP/NCAR reanalysis dataset.Cold extremes were defined as daily minimum tempera-tures falling below the 10th percentile at each grid point,and their frequencies were analyzed across different time scales.The East Asia(73°—145°E,4°—53°N)and North America(160°—12°W,25°—75°N)were selected as the dominant study regions.The results show that concurrent cold extremes between East Asia and North America predominantly occurred on a pentad time scale.While the frequency of such events has shown a decreasing trend since 2000,significant concurrent cold extremes continue to occur on smaller time scales.Synchronicity between the two regions was confirmed through lead-lag correlation coefficients analysis,highlighting a robust connection.Further analysis of the atmospheric circulations and thermodynamic conditions during concurrent cold extremes i-dentified key mechanisms.Zonal circulation patterns showed enhanced jet streams over the western Pacific Ocean and the West Atlantic Ocean,accompanied by negative geopotential height anomalies.These anomalies formed a Rossby wave-4 pattern,facilitating cold air advection from high latitudes to low latitudes.Meridional circulation a-nalysis supported this,demonstrating the role of jet stream variations in transporting cold air masses.From a ther-modynamic perspective,meridional temperature advection and non-adiabatic cooling emerged as the two most sig-nificant contributors to concurrent cold extremes in East Asia and North America.These findings provide new in-sights into the dynamics of concurrent cold extremes in the Northern Hemisphere and highlight the critical role of jet stream variability.Regional differences in temperature impacts between East Asia and North America were not-ed and need further investigation.Additionally,the resemblance of geopotential height anomalies to a Rossby wave-4 pattern suggests a need for further exploration of the underlying wave dynamics.This study advances the understanding of concurrent temperature extremes and their linkage to atmospheric circulation,offering a founda-tion for future research and prediction efforts.关键词
极端低温空间复合事件/高空急流/环流特征/热力学方程/合成分析Key words
spatially compound cold extremes/upper-level jet streams/circulation characteristics/thermodynamic equation/composite analysis引用本文复制引用
周王楚,黄丹青,姚素香..北美-东亚冬季极端低温空间复合事件及其与高空急流的联系[J].大气科学学报,2025,48(1):37-48,12.基金项目
国家重点研发计划项目(2022YFF0801601) （2022YFF0801601）
国家自然科学基金重点项目(42430605) （42430605）
