【摘要】 2003年4月17~18日山东春季大暴雨过程与暖切变、850 hPa中尺度低涡的发生发展、高温和丰沛的水汽密切相关。利用中尺度有限区域模式MM5对大暴雨过程进行了数值模拟,在数值模拟比较准确的基础上,利用模式输出的细网格资料,根据螺旋度(Helicity)理论结合稳定度条件,对这次暴雨演变过程中的螺旋度进行了诊断分析。结果表明,强对流和暴雨发生在不稳定大气中,正螺旋度大值中心出现的高度与对流发展强弱有关;500 hPa螺旋度正值区长轴与造成强对流的暖区弱切变和雷达带状回波走向一致;大暴雨产生在850 hPa螺旋度中心附近,螺旋度的强度变化对强对流系统的移动、发展及暴雨的发生有一定的指示意义。更多还原

【Abstract】 The heavy storm rainfall process in Shandong Province on 17~18 April 2003 is closely related to the warm shear,the occurring and developing of microscale low vortex on 850 hPa,high temperature and abandant moisture.The microscale limited-area model MM5 is used to simulate the heavy storm rainfall process.On the basis of better accurate simulation and using the fine-mesh data of model output, the helicity during the evolution process of heavy storm rainfall is diagnostically analyzed based on the helicity theory and stability condition.The results show that the hight occurred miximum value centre of positive helicity is related to the intensity and weakness of convective development when the severe convective storm occurs in the unstable atmosphere;the long axis in positive value area of 500 hPa helicity is consistent with the causing severe convective warm area′s weak shear and moving towards of radar band echo;the variation of helicity intensity has centain indication to the predictions of severe convective moving and developing,as well as heavy strom rainfall′s occurring when the heavy strom rainfall occurs near 850 hPa helicity centre.更多还原