Gaisberg塔的上行闪电：起始机制、闪电类型及大气影响
Upward Lightning at the Gaisberg Tower: Initiation Mechanism and Flash Type and the Atmospheric Influence
AI总结：
本研究利用随机森林模型结合Gaisberg塔测量与ERA5数据，发现-10°C等温线高度等大气变量能有效解释自发起始及不可探测上行闪电的发生条件。
摘要：
上行闪电比下行闪电罕见得多，需要高大（100+米）的结构才能触发。它可能由其他闪电放电触发，也可能是完全自发起始的。虽然常规闪电定位系统能可靠探测到下行闪电，但它们会漏掉仅由连续电流组成的特定上行闪电类型。在全球范围内，只有少数配备专门仪器的塔能够探测到这种闪电类型。风力涡轮机的普及加上上行闪电造成的巨大损失，使得有必要增进对自发起始和未被探测到的上行闪电亚型在何种条件下发生的了解。为了寻找有利于自发起始和不可探测的上行闪电的较大尺度气象条件，本研究使用了随机森林机器学习模型。它将奥地利Gaisberg山配备专门仪器的塔的直接测量数据与来自较大尺度大气再分析数据（ERA5）的解释变量相结合。大气变量能够可靠地解释上行闪电是由塔自发起始的还是由其他闪电放电触发的。最重要的变量是高大结构上方-10°C等温线的高度：它越近，自发起始上行闪电的概率就越高。两米温度和CAPE的量值也很重要。对于闪电定位系统无法探测到的上行闪电的发生，本研究发现其与附近没有闪电存在强相关性。
英文摘要：
Upward lightning is much rarer than downward lightning and requires tall ($100+$~m) structures to initiate. It may be either triggered by other lightning discharges or completely self-initiated. While conventional lightning location systems reliably detect downward lightning, they miss a specific flash type of upward lightning that consists only of a continuous current. Globally, only few specially instrumented towers can detect this flash type. The proliferation of wind turbines in combination with large damage from upward lightning necessitates an improved understanding under which conditions the self-initiated and the undetected subtype of upward lightning occur. To find larger-scale meteorological conditions favorable for self-initiated and undetectable upward lightning, this study uses a random forest machine learning model. It combines direct measurements at the specially instrumented tower at Gaisberg mountain in Austria with explanatory variables from larger-scale atmospheric reanalysis data (ERA5). Atmospheric variables reliably explain whether upward lightning is self-initiated by the tower or triggered by other lightning discharges. The most important variable is the height of the $-10~^\circ$C isotherm above the tall structure: the closer it is the higher is the probability of self-initiated upward lightning. Two-meter temperature and the amount of CAPE are also important. For the occurrence of upward lightning undetectable by lightning location systems, this study finds a strong relationship to the absence of lightning in the vicinity.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
