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)东北冷涡强降水(小时降水量≥5 mm)日变化特征,选取一天4个时次多个典型个例进行合成,用于消除单个个例系统生消过程引发强度变化的影响,分析产生强降水日变化特征的原因。结果表明:(1)暖季强降水集中出现在6-8月,又以7月最多,降水极值6月和8月最大。强降水的高频区位于冷涡东南象限,其次是东北象限。(2)与大范围强降水对应的冷涡中心位置和强度有明显的日变化特征:夜间冷涡偏强,位置偏北偏西;白天冷涡偏弱,位置偏南偏东。大范围强降水与高低空急流耦合相伴出现:强降水区位于高空急流核右后侧或左前侧、低空急流前侧和左前侧。高低空急流分布具有显著的日变化特征:下午全天最强,动力条件最好;夜间高空急流最弱,相应的高层辐散条件最弱。夜间以偏南气流水汽输送为主;白天西南气流水汽输送作用显著增强,到下午以西南气流水汽输送为主。(3)大范围强降水与较强气旋相对应,各时次气旋中心位置相差不大。气旋强度和地面露点温度均有显著的日变化特征。强降水高频区一般出现在气旋中心及其北侧或东侧的气压梯度大值区内,与较大的露点温度相对应。(4)高频次强降水与局地地形分布相关。夜间中小尺度垂直环流对冷涡东侧强降水的量级及高频区分布作用更突出。夜间冷空气更活跃,降水空间梯度大,强降水局地性更强、受地形影响更显著;白天地形对降水的增幅作用不明显。山脉背风坡降水量普遍大于迎风坡。
Using the hourly precipitation data of 80 national stations in Heilongjiang Province,the NCEP/NCAR and the EC-ERA5 reanalysis data,the diurnal variation characteristics of heavy precipitation(hourly precipitation≥5 mm)by Northeast Cold Vortex(NECV)during the warm season(from May to September)from 1981 to 2022 were analyzed.Multiple typical cases at four times a day were selected for synthesis,which was used to eliminate the influence of intensity change caused by the generation and extinction process of a single case system,and analyze the reasons for the diurnal variation characteristics of heavy precipitation.The results showed that:(1)the heavy rainfall in the warm season was concentrated in June to August,and the heavy rainfall occurred mostly in July,and the maximum precipitation was the heaviest in June and August.The high frequency region of heavy precipitation was located in the southeast quadrant of NECV,the lower frequency could be found in the northeast quadrant.(2)The central position and intensity of NECV corresponding to the largescale heavy precipitation had obvious diurnal variation characteristics:NECV was stronger at night,and its location was north and west.During the day,NECV was weak,and its position was south to east.The large range of heavy rainfall coupled with the high and low air jet stream appeared:the strong rainfall area was located in the upper jet stream core right back or left front side,the lower jet stream front and left front side.The distribution of the high and low air jet showed significant diurnal variation:the strongest in the afternoon and the best dynamic conditions;the upper level jet stream is weakest at night,and the corresponding upper level divergence conditions are weakest.The southerly air vapor transport was the main at night;During the day,the water vapor transport of the southwest air stream was significantly enhanced,and in the afternoon,the water vapor transport of the southwest air stream was mainly.(3)The wide range of heavy precipitation was corresponded to strong cyclonic activities,and there was little difference in the central positions of cyclones among different times.Both the cyclone intensity and the surface dew point temperature had significant diurnal variation characteristics.The high frequency area of heavy precipitation generally appeared in the large pressure gradient area of the cyclone center and its north or east side,corresponding to the larger dew point temperature.(4)The high frequency of heavy precipitation was related to the distribution of local topography.The mesoscale vertical circulation at night played a more prominent role in the magnitude and high frequency distribution of heavy precipitation on the east side of NECV.The cold air at night was more active,the spatial gradient of nighttime precipitation was larger,and the heavy precipitation was more localized and affected by terrain more significantly.The effect of topography on increased precipitation in daytime was not obvious.The amount of water on the leeward slope was generally greater than that on the windward slope.
作者
任丽
刘颖
REN Li;LIU Ying(Institute of Atmospheric Environment of China Meteorological Administration,Shenyang 110166,Liaoning,China;Meteorological Observatory of Heilongjiang Province,Harbin 150030,Heilongjiang,China;State Key Laboratory of Climate System Prediction and Risk Management/China Meteorological Administration Climate Studies Key Laboratory,National Climate Centre,China Meteorological Administration,Beijing 100081,China)
出处
《高原气象》
北大核心
2025年第4期961-973,共13页
Plateau Meteorology
基金
中国气象局沈阳大气环境研究所联合开放基金课题(2024SYIAEKFZD04)
中国气象局创新发展专项(CXFZ2023J011)
中国气象局“揭榜挂帅”项目(CMAJBGS202313)
黑龙江省自然科学基金联合引导项目(LH2024D023)。
关键词
东北冷涡
日变化
空间分布
地形
强降水
Northeast Cold Vortex(NECV)
daily variation
spatial distribution
terrain
heavy precipitation
