螺旋度技术在辽宁3月4日大暴雪中的应用

Application of Helicity in the Snowstorm on March 4

利用辽宁2007年3月3日-4日的暴雪资料和NCEP资料,应用螺旋度技术分析了此次大暴雪天气过程。结果表明,暴雪发生前后,暴雪区的螺旋度分布特征明显;垂直分布上,暴雪发生时雪区上空大致为上负下正分布,中上层有较强的负螺旋度;水平分布上,暴雪中心位于低层螺旋度中心北侧的500 hPa正值中心与东北侧负值中心的连线之间。

By use of the big snowstorm data and NCEP data on March 4,2007,the helicity technology was applied to analyze the process of the big snowstorm.The results showed that before and after it was occurred,the helicity distribution of big snowstorm was obvious.In the vertical distribution,there was a negative minimum centre of the helicity near the upper and a positive maximum centre of the helicity near the lower over the heavy rain area.In the horizontal distribution,the big snowstorm centre was at the connection line between 500 hpa positive value of north centre and negative value of the northeastern center in the lower helicity center