海南2020年4月22日出现云带持续的强降水天气，这是冷空气偏西下锋消天气过程的重要天气类型之一，深入研究其降水机理，对人们的生产生活具有重要意义。利用常规地面、高空、卫星和雷达资料，特别使用NCEP/NCAR的fnl再分析资料，对降水云带的结构及其特征进行分析研究。结果表明：1) 海南岛中下层的相对湿度变化不大，上层有水汽补充。2) 海南岛吹反气旋式，下层东风，中下层南风，中上层西南风。3) 海南岛下层有一个正涡度区；往上有一正一负涡度；中下层有一正和二负涡度，西北部海面的正涡度区向东南延伸，西部和东北部各有一个负涡度；上层有二正和二负涡度，变为鞍马型，西北部的正涡度区影响减少，东南部的正涡度区影响增加。4) 海南岛的最大风为西南风，风速在22~27 m/s之间，其温度在？65℃~？59℃之间，高度在13,280~13,947 m之间。5) 海南岛的对流风为西到西南风，风速在7~16 m/s之间，其温度在？78℃~？77℃之间，高度在16,080~17,264 m之间。6) 海南岛的对流有效位能南部在1377~1650 J/kg之间，西部在365~716 J/kg之间，北部较低，在270~284 J/kg之间。7) 海南岛的对流凝结高度在4826~4988 m之间。8) 海南岛的柱体云水为0.06 kg/m2，柱体可降水为45.9~54.1 kg/m2之间。
The process of continuous heavy precipitation occurred on April 22, 2020, which is caused by one of the important weather types: the front disappearance of cold air westward. The study of its precipitation mechanism is significant to society. The structure and characteristics of precipitation cloud are analyzed using the radiosonde data, high-altitude observation, satellite and radar data, especially the NCEP/NCAR fnl data. The results show that: 1) The relative humidity of the middle height of Hainan Island is relatively stable, and the upper height is supplemented by water vapor; 2) The dominant wind direction of Hainan Island is anti-cyclone, which is east wind in the low height, south wind in the middle height, and southwestern wind in the upper layer; 3) There is a positive vorticity area in the low height of Hainan Island; there is a positive and a negative vorticity upwards; the middle height has a positive and two negative vortices. The positive vorticity area of the northwest sea surface extends to the southeast, and there is a negative vorticity in the west and northeast. There are two positive and two negative vortices in the upper layer, which becomes saddle-shaped. The influence of the positive vorticity area in the northwest is reduced, and the influence of the positive vorticity area in the southeast is increased; 4) The maximum wind on Hainan Island is southwest wind, with wind speed between 22 and 27 m/s, temperature between ？65？C and ？59？C, and altitude range from 13,280 to 13,947 m; 5) The convective wind on Hainan Island is from west to southwest, with wind speed ranging from 7 to 16 m/s, temperature ranging from ？78？C to ？77？C, and height ranging from 16,080 to 17,264 m; 6) The CAPE of Hainan Island is between 1377~1650 J/kg in the south, 365~716 J/kg in the west, and lower in the north, between 270~284 J/kg; 7) The convective condensation height of Hainan
