基于小波的雷暴强放电前地面电场的多重分形分析

根据远离平衡的复杂系统演化的雪崩性和自相似倍增串级性，强调了多重分形工具的重要；利用青藏高原中部地区雷暴放电的地面电场仪资料，基于多重分形谱的小波估计方法，对强放电前雷电活动的多重分形特征进行了分析，发现多重分形谱可用推广的多重分形二项倍增串级模式描述，强放电前放电过程具有强烈的奇异性和明显的多重分形性，谱宽度Δα＞1.6，最小标度指数α_min＜-0.3；随着放电的活跃，Δα表现出明显的增加，而强的放电则发生在随后Δα的高值区或下降区，并对相关的原因进行了讨论. 关键词： 多重分形 雪崩 倍增串级 小波 闪电放电

Wavelet-based multifractal analysis of ground electric field before occurrence of strong discharge in thunderstorm

It is considered that complex systems far from equilibrium are evolved in avalanche and self similar multiplicative cascade way, and have characteristics of multifractality. By using the ground electric field data obtained in the middle of Qinghai-Xizang plateau region, multifractal behavior of lightning discharges in thunderstorm is investigated with wavelet-based multifractal method. It is found that strong singularity and multfractality are involved in the strong lightning discharges, the minimum exponent α_min is less than -0.3, and the width of spectrum Δα is greater than 1.6, and the scaling behavior is consistent with the modified version of the binomial multiplicative cascade multifractal model. It is also shown that Δα increases with the enhancing of the discharge activity, and strong lightning happens in regions where Δα is high or is decreasing, the related reason is discussed.