Analysis of Causes and Circulation Anomaly of the Continuous Rain in Wheat Harvest Season 2023
The continuous rain process in Henan Province from 25 to 30 May 2023,which had the longest duration and heavies impact in the same period since 1961,led to a significant reduction in wheat yield and quality,making some seed fields in southern,central and eastern Henan lose their planting val-ues,so this rain event is known as"rotten field rain".In this article,the large-scale circulation situation and impact system are analyzed based on the MICAPS conventional observation,NCEP reanalysis data and ECMWF numerical prediction products.The results are as follows:(1)This continuous rain event oc-curred in the background of abnormal atmospheric circulation.The western Pacific subtropical high was significantly stronger and the 5 d moving average position of the ridge line was 8 latitudes northward,crossing the 25°N line.At the same time,the Siberian High was also unusually strong and active towards the south.(2)A deep cold vortex from the Ural Mountains blocking System that maintained for a long time in the northwest of Xinjiang,China,caused the formation of a stable zonal circulation in 35°-40°N,which brought about cold air constantly splitting from the bottom of the cold vortex,moving to southeast and affecting Henan from west to east.The western Pacific subtropical high rapidly jumped to north and extended to the west as a long-distance super typhoon approached,forming a broad and deep conveyor belt of warm and humid air extending from the South China Sea to the mid-latitudes in its periphery,and finally converging into a low-level jet stream in the northwest of Henan province.With the warm and humid airflow spreading to the north,there were obvious convergence of air mass and water vapor in low-troposphere in front of the high wind speed zone,causing the developing of ascending motion,which led to the occurrence of rainstorm in many places and localized severe rainstorm.(3)The encounter of two anomalous weather systems in the north and south contributed to the stable maintenance of the mid-lati-tude energy front zone,and the frontal uplift increased and maintained precipitation in the warm section.(4)The numerical models have made accurate forecasts of the medium-and short-term circulation trends and the impact systems,but the forecast of precipitation magnitude and its distribution needs to be further refined.
continuous rainy weathercirculation anomalysuper typhoonblocking system
万方数据
维普
