【摘要】 使用黑龙江省80个国家站小时降水量资料、NCEP/NCAR和EC-ERA5再分析资料，统计1981～2022年暖季（5～9月）所有东北冷涡暴雨过程强降水和低空急流特征及强降水日变化特征。选取一天4个时次多个典型个例进行合成，分析产生强降水频次日变化的原因。结果表明：1）暖季80%以上的东北冷涡暴雨个例与低空急流相伴出现。850 hPa急流出现的频率最高、持续时间最长，对强降水和降水极值的预报具有指示意义。2）下午偏南风低空急流最强，其他时段东南风低空急流最强。两处急流均在850 hPa具有明显的垂直风切变。3）强降水频次的日变化峰值出现在下午，日变化谷值出现在后半夜。强降水高频区在冷涡东南象限，次高频区在东北象限。4）夜间降水量分布不均匀、空间梯度大，强降水与中层干冷空气活动有关，对流不稳定更有利于强降水发生。下午至前半夜，强降水发生在低空急流左侧水平风速切变最大的区域。复杂地形造成的小尺度垂直环流可以加强降水。更多还原

【Abstract】 Using the hourly precipitation data of 80 national stations in Heilongjiang Province, the NCEP/NCAR and the EC-ERA5 reanalysis data, the characteristics of heavy precipitation and low-level jet during the Northeast Cold Vortex(NECV) rainstorm process and the diurnal variation of heavy precipitation in the warm season(from May to September)from 1981 to 2022 are analyzed. Several typical cases at four times a day are synthesized to analyze the causes of diurnal variation of heavy precipitation frequency. The results show that: 1) In the warm season, more than 80% of NECV rainstorm cases are accompanied by low-level jet. The 850 hPa jet stream at 850 hPa has the highest frequency and the longest duration, which is indicative for the prediction of heavy precipitation and precipitation extremes. 2) The southerly low-level jet is the strongest in the afternoon, and the southeast low-level jet is the strongest in other periods. Both jet streams have significant vertical wind shear at 850 hPa. 3) The peak of the diurnal variation of heavy precipitation frequency appear in the afternoon, and the trough of the diurnal variation appear in the late night. The highest frequency region of heavy precipitation is the southeast quadrant of NECV, followed by the northeast quadrant. 4) The distribution of precipitation at night is uneven, the spatial gradient is large, the heavy precipitation is related to the activities of the dry cold air at the middle level, and the convective instability is more conducive to the occurrence of heavy precipitation.During afternoon to early midnight, heavy precipitation occurs in the area with the largest horizontal wind edge on the left side of the low-level jet stream. Small-scale vertical circulation caused by complex terrain can enhance the precipitation.更多还原