兰州周边地区地闪闪区统计特征Ⅰ:环境风场及稳定度特征

Statistical Characteristic of Cloud-to-ground Discharge Area around Lanzhou PartⅠ:Characteristic of Environmental Wind Field and Stability

统计分析了兰州周边地区6h内地闪闪区分布特征与200hPa高空急流、垂直风切变、高低空辐合辐散等环境风场以及K指数、条件对流性稳定度指数的关系,得到了地闪闪区与通气管指数分布的5种主要类别以及与高低空辐合辐散、稳定度指数分布的结构模型;指出了目前研究地闪频次与气象参数关系中存在的问题,通过分析不同时间或空间范围内的地闪频数与K指数的相关关系证实了这些问题的存在,建议在分析地闪频次和气象参数的关系时考虑选取有益的统计地闪次数的时间或空间范围。

By analyzing the distribution characteristic of cloud-to-ground discharge area during 6 hours,upper level jet stream at 200 hPa,vertical wind shear,convergence and divergence of upper or lower level,K index and Icondi-Conve index,the five main distribution types of cloud-to-ground discharge area and vent pipe index,the structural models of convergence and divergence of upper or lower level and stability parameters are found.The problems existing in recent researches on the relationship between cloud-to-ground discharge frequency and meteorological parameters are pointed out.The existence of these problems is confirmed by analyzing the relationship between cloud-to-ground discharge frequency and K index with varied time and area.The conclusion suggests that appropriate time and area should be selected in order to get more accurate result.