This paper analyzes three long duration heavy precipitation events in Liaoning Province using NCEP 1 °× 1° grid reanalysis data,FY-2E infrared 0.1 °×0.1° TBB data and automatic weather station data.The relationship between TBB and precipitation and the characteristics and maintenance mechanism of mesoscale environmental field are studied.The conceptual forecasting model of long duration heavy precipitation in Liaoning is initially established.The results demonstrate that:When the pattern,location and intensity of subtropical high are conducive to heavy precipitation occurring in Liaoning,a favorable environmental background for the occurrence and maintenance of heavy precipitation is provided by the long-time interaction between the moist warm air transferred by low-level jet on the west side of subtropical high and the arid cold air on upper levels.There must be a continuous and stable water vapor transport before the occurrence of heavy rainfall,and there is no significant change in the intensity of water vapor transport and the thickness of wet layer in the process of heavy rainfall.The time length of strong vertical movement has good correspondence with the duration of heavy rainfall,and it is generally weak unstable stratification or neutral stratification on upper levels during heavy precipitation.The heavy precipitation can occur not only in the inner or edge of the cool cloud area of strong convective cloud but also in the warm cloud area where TBB value is small.TBB value is not necessarily related to precipitation intensity,but the rapid decrease of TBB value indicates imminent heavy rainfall.It is necessary to pay attention to water vapor transport,convergence and upward motion below 900 hPa in order to forecast location and intensity of precipitation in the warm cloud with low center of mass.These conclusions are helpful to deepen the understanding of the cause of long duration heavy precipitation in Liaoning area and provide clues for forecasting.%利用NCEP 1°×1°格点再分析、FY-2E相当黑体亮温TBB和地面加密自动气象站等资料,分析了辽宁3次典型长历时强降水TBB值与降水强度的关系、中尺度环境场特征及维持机制,并初步建立了辽宁长历时强降水概念预报模型.结果表明:在副热带高压的形态、位置和强度有利于辽宁产生强降水的大尺度形势下,副热带高压西侧低空急流持续输送的充沛暖湿空气与高空干冷空气在同一地点长时间相互作用,为强降水的发生和维持提供了有利的环境背景条件.强降水持续时间与其上空的强垂直速度持续时间有很好的对应关系,强降水持续时高空一般为弱的不稳定或中性层结.强降水不仅可出现在对流云团发展旺盛的冷云区内部或边缘,也可发生在TBB值较小的暖云区内.TBB值的大小与降水强度没有必然的关系,但TBB值的快速减小都预示强降水即将发生.这些结论有利于深化认识辽宁地区长历时强降水的成因并为预报提供线索.
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