Causes analysis of the"21·7"extreme rainstorm in Henan and construction of a three-dimensional conceptual model
By analyzing the topographic effect,atmospheric circulation and water vapor transport channels at different heights of the"21·7"extreme rainstorm event in Henan Province,the main conclusions were shown as follows:(1)the southeast airflow formed by Typhoon"In-Fa"and the subtropical high infiltrates the trumpet-shaped terrain of Henan at the bottom layer.Under the combined effect of terrain thermal uplift and dynamic blocking uplift,it is conducive to the formation of precipitation in front of the mountains.(2)In the middle layer of 500 hPa,the Zhengzhou vortex is located within the"saddle shaped fields"between two high pressure,and this circulation configuration leads to the interaction of Typhoon"In-Fa","Cempaka",and tropical low pressure to form three streams of airflow directly reaching Henan.At the 200 hPa upper level,the divergent flow in the rainstorm area sinks eastward into the upper cold vortex in the East China Sea at the same latitude,and its secondary circulation further strengthens the strength of the Henan cloud cluster.(3)Typhoon"In-Fa"and"Cempaka"transported abundant water vapor to the central and western parts of Henan,but were obstructed by the terrain of Taihang Mountains and Funiu Mountains,forming strong water vapor convergence in front of the mountains.(4)The conceptual model of extreme rainstorm in Henan organically links the circulation,typhoon,low pressure system,trumpet-shaped topography and other precipitation factors through the water vapor transport channel and secondary circulation,and then puts them into the same framework.Understanding the operation mechanism and interaction of these factors from a macro perspective can deepen the understanding of the causes of the extremely heavy rainstorm.
rainstorm genesistopographic effectstyphoonwater vapor transport channelconceptual model
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