我国南方林区云地闪特征和落区预估研究

Cloud-to-Ground (CG) lightning is the main trigger of the forest lightning disasteres.Because of its instantaneous and strong thermo-electric effects, the destruction to ecosystem is serious.Now the research in this aspect maybe has some limitations.As far as study fields are concerned, southern forest regions do not have much attention, and for methods of the research, surface layer observations statistics is common,but the way about the combination of thunderstorm cloud-CG lightning-forest surface conditions remains rare. The major aim of this study is to break down these limitations.Based on multi-source remote sensing data,combined with macroscopical and microscopic methods, such as statistics, numerical simulation, forest land surface and geological characteristics,data assimilation, electrification intra-cloud, this study will extend new ideas on the research of southern Chinese forest CG lightning and corresponding disasters. The desired south experimental forest multi-source material should be collected, to get CG lightning statistical characteristics and its disaster patterns.The remote sensing detection material of different temporal-spatial scales should be fused for south experimental forest thunderstorm meteorological environment accurate simulation，which is done by weather numerical model ARPS-ADAS，according to time cycling scheme. Then, using statistics and coupling method，from a macroscopic view，the 1st estimated lightning falling locations is obtained by coupling CG lightning statistical model and mesoscale assimilation modle. Meanwhile, from a microscopic view，using integral prediction method，the 2nd estimated lightning falling zones comes from a growth rate model of vertical atmosphere electric intensity and assimilations.After that, these two estimated method and value will be revised by auxiliary criterion, finally get the forest CG lightning characteristics and the dynamic distributions in south China.This study would have significant meaning on the research of forest lightning disasters and ecological protection.

森林雷电灾害的根本是云对大地的云地闪。由于其瞬时强热电效应，造成的生态系统破坏也很严重。目前这方面研究或有局限。从区域来说，对南方林区关注不多，研究方法也主要是近地层实测数据统计，对雷暴云-云地闪-地表状况联合考虑甚少。本研究旨在突破该局限，基于多源遥感探测数据，联合统计、数值模拟、林区地质地表特征研究、资料同化、云中起电等宏观微观方法，扩展新思路关注南方林区云地闪及灾害。收集实验林区多源资料，获取云地闪统计特点及灾害规律，由气象模式ARPS-ADAS以时间循环方案融合同化多源遥感信息，得到雷暴环境的精确模拟。从宏观角度，把云地闪统计模型与中尺度同化模型相耦合，得到统计耦合法预估的闪电落区1，从微观角度，把同化模拟与垂直大气电场增长率模型相结合，得到积分预测法预估的闪电落区2，由各约束判据对其反馈修订，最终得到南方林区云地闪特征及动态分布。该研究将对林区雷电灾害研究和生态保护产生重大意义。

森林雷电灾害的根本是云对大地的云地闪击。由于其瞬时强热电效应，造成的森林灾害主要体现在树木损毁和森林雷击火灾。目前这方面研究或有局限。从区域来说，对南方林区关注不多，研究方法也主要是近地层实测数据统计，对雷暴云-云地闪-地表状况联合考虑甚少。随着华南气候干暖化，森林雷击灾害正在华南天然林区逐步增加。. 本项目选取同一纬度带上的我国南方两处天然林区为实验区，分别是江西武夷山地区（铅山）和四川木里地区。. 本研究从宏观和微观角度对林区云地闪进行了全方位分析。借助闪电定位仪网LLS资料和世界范围闪电定位网WWLLN资料实验区云地闪时空分布特征、云地闪重要影响因子等进行探索；借助RegCM3区域气候模型，研究森林植被条件下区域气候变化趋势；借助ARPS-ADAS数据同化系统关注林区近地层雷暴云三维结构特征、云中微物理过程、云中起电粒子模拟等；同时联合云中电场增长模型，设定电场击穿阈值，借助ARPS-ADAS得到云地闪落区预估范围。得到结论：1、华南地区云地闪频次呈现逐年递增趋势。2、雷击灾害重点频发时段表现在18:00-19:00；常发于低海拔地区。闪击电流绝对值在20-60KA之间的负地闪是雷击灾害主要云地闪类型。3、3月、10月云地闪变化与当月最低温呈现较强正相关、降水量呈较弱负相关，在气候干暖化背景下，最低温与降水量可以作为森林雷击灾害的指示性参数。4、森林植被对于气候变化的作用突出表现在降低地表附近风速、增加湿度、减少日照时数等。虽然增加植被面积未必能促使降温，但可以抑制增温趋势。5、使用ARPS-ADAS进行RS资料同化获得雷暴云三维结构，需要使用“时间循环同化”，对应的参数化详见结题报告。6、雷暴云电场击穿阈值设定为250KV/m。. 该研究可以把南方林区云地闪从高空到地表动态监控，将对华南林区雷电灾害研究和生态保护产生重大意义。