冬季乌拉尔山阻塞高压（以下简称乌山阻高）是导致我国出现大范围寒潮天气的重要影响系统， 探究其建立和维持过程与位势高度季节内振荡的联系能够为我国延伸期天气预报及短期气候预测提供参考因子。本文基于欧洲中期天气预报中心（European Centre for Medium-Range Weather Forecasts， ECMWF）提供的1979/1980 -2019/2020年ERA5逐日再分析数据， 采用主、 客观相结合的方法， 筛选得到114次冬季乌山阻高事件， 累计阻高日数591天。利用功率谱分析、 相关分析、 合成分析等统计方法， 分析乌山阻高与500 hPa位势高度季节内振荡之间的可能联系。结果表明： （1）近41年冬季乌拉尔山地区位势高度存在10~20天、 30天及45天左右的显著周期。通过多尺度分析发现， 在乌山阻高建立与维持期间位势高度的不同时间尺度分量贡献不同， 其中对乌山阻高建立贡献最大的是10~20天的准双周位势高度正异常， 阻高维持则决定于20~80天的季节内尺度位势高度正异常。在阻高建立和维持过程中， 准双周位势高度异常具有自西向东的传播特征， 季节内尺度位势高度异常无明显传播。（2）根据两次阻高事件发生的时间间隔长短将阻高事件分为连续阻高事件和其他阻高事件， 通过多个例合成分析和典型个例分析， 发现对于连续阻高事件而言， 位势高度异常的20~80天振荡对其建立和维持贡献最大， 但无明显传播特征， 准双周尺度位势高度异常表现出向西传播的信号， 而其他非连续阻高事件与不同时间尺度大气环流的联系则与所有阻高事件合成的结果相似。

The Ural blocking high （UB） in winter is an important influence system leading to widespread cold snap in China.Exploring exploring the connections between its establishment and maintenance processes and intra-seasonal oscillations of geopotential height can provide reference factors for extended range forecasting and short-term climate prediction.By using the ERA5 daily reanalysis data provided by European Centre for Medium-Range Weather Forecasts （ECMWF） from 1979/1980 to 2019/2020， 114 winter UB events were selected by using a combined subjective and objective method， in which the cumulative number of blocking high days reached 591.The connections between the Ural blockings and the intra-seasonal oscillations of the 500 hPa geopotential height were analyzed by using power spectrum analysis， correlation analysis， synthesis analysis and other statistical methods.The results show that： （1） Geopotential height over the Ural Mountains has significant periods of 10~20 days， 30 days and 45 days during the last 41a winter.Through multi-scale analysis， we find that different time scale components of the geopotential height contribute differently during the establishment and maintenance processes of the Ural blockings， where the largest contribution to the establishment of Ural blocking highs is the quasi-biweekly geopotential height anomaly （10~20 days）， and the maintenance of blocking high events is determined by intra-seasonal oscillations with a scale of 20~80 days.During the establishment and maintenance processes of blockings， the quasi-biweekly geopotential height anomaly propagates from west to east， while the intra-seasonal oscillations of the geopotential height anomaly have no significant propagation.（2） According to the time intervals between the occurrences of two events， blockings are classified into continuous blocking high events and other blocking high events.Through multiple case synthesis analysis and typical individual case analysis， we find that for continuous blocking high events， the intra-seasonal oscillations of the geopotential height anomaly contribute most to their establishment and maintenance processes， but have no significant propagation.The geopotential height anomaly shows a westward propagating signal on the quasi-biweekly scale.The connections between other non-continuous blockings and atmospheric circulation at different time scales are similar to the results of all blocking high events.