Diagnostic Analysis of the Helicity During a Heavy Dust Storm Weather Process in Hexi Corridor

Based on the reanalysis data of NCEP,a regional storng dust storm in Hexi corridor was analyzed from the horizontal and vertical distribution characteristics of the total helicity and helicity.The results showed that the dust storm occurred in the intensive isoline or the zeroline of the negative helicity area.There was the negative helicity at 300 hPa and the positive helicity at 700 hPa over duststorm area.The negative center of the helicity was growing obviously with the outbreak of the duststorm.The vertical helicity distribution characteristic was negative at the high level and positive at the low level.The helicity indicated the outbreak area of dust storm very well.