【摘要】 利用NCEP再分析资料、ERA5再分析资料和自动站逐小时观测资料对2014年7月19日影响黑龙江省西部中尺度对流过程的天气尺度、中尺度环流背景及地面要素演变特点进行分析。结果表明:此次强降水过程是在台风与西风带系统远距离作用的背景下,由高空急流、冷涡、低层切变线与冷锋相互配合产生的。过程持续时间短、强度大、局地性强。副高外围偏南风引导远距离台风携带的暖湿气流向东北地区输送,与高空冷涡后部干冷空气配合,形成低层暖湿高层干冷的不稳定层结,为中尺度对流系统的发生发展提供了有利的环境条件。冷锋和喇叭口地形的辐合抬升相互配合,使暖湿气流抬升,冲破中层抑制,触发对流,使前期累积的不稳定能量释放。高空急流的辐散和通风作用使上升运动和不稳定层结维持,降水持续,且强度增强。受干冷空气卷入和强降水粒子蒸发的影响,系统后部出现较强冷池,使强降水同时伴有雷暴大风。随着系统后部冷池及冷空气主体的抬升,暖湿空气抬离地面,过程结束。更多还原

【Abstract】 Based on the global reanalysis from FNL(NCEP final operational global analysis) and ERA5(fifth version of the European Centre for medium-range weather forecasts reanalysis model)and hourly observation at the automatic meteorological station, the mesoscale and synoptic characteristics as well as the development features of land-surface meteorological variables that affected the heavy rain in western Heilongjiang on July 19 th, 2014 were analyzed. It shows that, first, this heavy precipitation event was caused by the combined function of the high-altitude jet stream, cold vortex,low-level shear line and cold front under the background of the long-distance effect of the typhoon and the westerly belt system.Furthermore, the characteristics of short duration, high intensity and strong localization caused by β-α mesoscale system has been shown clearly in this case study.Unstable stratification caused by the warm and humid airflow carried by southern wind from the west of the subtropical high to the northeast region with the dry and cold air carried by the cold vortex at the upper layer, which provided favorable environmental conditions for the occurrence and development of the mesoscale convection system.Meanwhile, the cold front triggered convection to release the unstable energy. Finally, the convective was triggered by the cooperation of both cold wave and convergenceuplift function of trumpet topography, which induced the upward movement of warm and wet air stream and further ditroy the middle-layer confinement and released the unstable energy accumulated earlier.The process was maintained by the divergence and ventilation of the upper jet with the precipitation sustained and the intensity enhanced. In this stage, due to the influence of dry and cold air entrainment and evaporation of heavy precipitation particles, a strong cold pool appeared at the rear of the system, which made the heavy precipitation accompanied by thunderstorm wind. After this stage,with the general uplift of the cold pool and the main body of cold air, the warm and humid air was lifted off the ground, and the process ended.更多还原