Observational Facts of Sustained Departure Plateau Vortexes

By using the observed atmosphere data twice a day for 15 years(1998~2012), the rainfall data and Tropical Rainfall Measure Mission(TRMM) data as well as the yearbook of Plateau Vortex and Shear Line, the characteristics of Sustained Departure Plateau Vortexes (SDPV) are analyzed based on the principles of both the synoptic meteorology and the statistics. Some new useful observations are revealed about the characteristics of the SDPV activities, as well as some new understandings on it. The investigations show the following facts: 1) T he active period of SDPVs are in June, July and August( most in July), unlike unsustained Departure Plateau Vortexes (DPVs) with undifferentiated frequency in 3 months; 2) The SDPVs, generated mainly in the Qumalai neighborhood, move eastward or northeastward situated in a sheared surrounding, while the DPVs are mainly led by trough and, move eastward or southeastward; 3) The SDPVs influence widely in China, even far to Korean Peninsula, Japan and Vietnam; 4) The SDPVs change their intensities and properties on the way to the east. Most of them become stronger in intensity and produce downpour or sustained regional rainstorm to the south of Yellow River; 5)The longer the SDPV remains, the more baroclinity it is; 6) When a SDPV moved to the sea, its center geopotential height descends and rainfall increases in all probability; 7)A SDPV might spin in the bend of Yellow River as a tropical cyclone existing in the East China Sea. It could also move oppositely to a landed tropical low pressure coming from the sea to the east of Taiwan or from the South China Sea.