伊犁河谷复杂地形影响下地闪活动特征

Characteristics of cloud-to-ground lightning activities under influence of complex terrain over Ili River Valley

摘要:

基于2015—2023年伊犁河谷ADTD闪电定位资料、DEM高程及土地利用类型数据，研究了伊犁河谷地闪活动的时空变化特征及其与地形、土地利用类型的关系。结果表明：伊犁河谷地闪主要发生在暖季（4—9月），6月最多，日变化为单峰型，最活跃时段为17—22时，亦是一天中地闪强度最弱时段；地闪多发生在山区或平原与山地过渡区，三个高发区域分别位于特克斯南部山脉、乌孙山南坡和北坡、霍城县至伊宁县北部山区；伊犁河谷51.2%区域的地闪最活跃月份为6月，43.8%区域为7月；地闪频次日峰值时间自西向东明显推迟，且平原区域峰值时间晚于山区；地闪频次和密度随海拔升高呈先增后减的特征，在1500—2500 m高度层频次多且密度大；地闪密度随坡度增加呈先增后减的特征，在18～21°最大，而地闪频数、强度与坡度呈显著负相关；伊犁河谷坡向北地闪频次最多，坡向东地闪密度最大；就土地利用类型而言，草地地闪频次最多，林地地闪密度最大。

Abstract:

Based on the ADTD lightning location data (2015-2023), DEM terrain elevation data and land use type data in the Ili River Valley, the temporal and spatial distribution characteristics of cloud-to-ground (CG) lightning activities and their correlation with topography and land use type were studied. The results showed that: CG lightning in the Ili River Valley mainly occurred in the warm season (April-September), with the highest frequency in June. The diurnal variation of CG lightning frequency demonstrated a unimodal pattern, with the most active period between 17:00 and 22:00, which simultaneously corresponded to the weakest CG lightning intensity observed within a day. The CG lightning activities in the Ili River Valley predominantly occurred in mountainous terrain or transitional zones between plains and mountains, with three high-frequency regions located in the southern mountains of Tekes County, the southern and northern slopes of Wusun Mountain, and the northern mountainous region from Huocheng County to Yining County. June constituted the most active month for CG lightning in 51.2% of the study area, while July predominated in 43.8% of the territory. The diurnal peak occurrence time of CG lightning frequency exhibited a pronounced eastward delay, with plains regions demonstrating later peak times than mountainous regions. The frequency and density of CG lightning initially increased then decreased with rising elevation, reaching maximum values at 1500-2500 m. Regarding slope effects, CG lightning density followed a unimodal pattern peaking at 18-21°, while CG lightning frequency and intensity demonstrated statistically significant negative correlations with increasing slope angles. North-facing slopes exhibited the highest frequency of CG lightning, while east-facing slopes showed the greatest density. Among land use types, grasslands recorded the highest CG lightning frequency, whereas forested areas demonstrated the maximum density.