Convection initiation over central–eastern China: Statistics show higher frequencies over mountains with less stringent atmospheric conditions and more heterogeneous surface characteristics

IF 4.4 2区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Research Pub Date : 2025-08-20 DOI:10.1016/j.atmosres.2025.108438

Qian Wei , Jianhua Sun , Xianhong Meng , Yuanchun Zhang , Linlin Zheng , Zheng Ma

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引用次数: 0

Abstract

A total of 11,646 convection initiation (CI) events (CIEs) were identified during the warm seasons (May to September) from 2016 to 2020 in the middle reaches of the Yangtze River Basin (MR-YRB), using a CI identification method and composite reflectivity (CR) data. CI occurs more frequently in July and August, accounting for 62.7 % of the total CIEs, and predominantly between 11:00 to 16:00 Beijing Time (BJT), representing 62.2 % of the total CIEs. These events are distributed across different terrains, including mountains (elevations exceeding 400 m), foothills (elevations ranging from 100 to 400 m), and plains (elevations ranging from 0 to 100 m). The spatial distribution of high-frequency CIE regions is closely associated with mountains within the MR-YRB. Mountains experience twice as many CIEs as plains, even under conditions of weaker instability and vertical wind shear, although these events tend to be smaller and short-lived. In contrast, foothill CIEs exhibit the largest convective areas. A single peak in CI frequency occurs at noon (12:00–13:00 BJT) across all terrain types, coincides with the highest initiation elevations (400–600 m) and largest convective areas under conditions of maximum thermal instability. Heterogeneity in soil moisture (SM, 0–5 cm) and surface heat fluxes (SHF) has potential to play a crucial role in the triggering of noontime CIEs. Mountain CIEs exhibit the highest degree of heterogeneity. They typically occur in regions with higher SM than surrounding areas and proximity to areas with enhanced SHF. Higher SM may provide favorable conditions for CI by increasing low-level moisture and moist static energy at mountain CI sites. Pronounced SM heterogeneity may further promote CI by facilitating either latent or sensible heating processes, which can generate mesoscale thermal circulations in the vicinity of pronounced SM gradients.

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中国中东部地区的对流开始：统计数据显示，在大气条件不太严格和地表特征不均匀的山区，对流发生的频率更高

利用对流起始（CI）识别方法和复合反射率（CR）数据，对2016 - 2020年暖季（5 - 9月）长江中游地区共11646个对流起始（CI）事件进行了识别。CI多发于7、8月，占总CIEs的62.7 %，主要发生在北京时间11:00 - 16:00，占总CIEs的62.2 %。这些事件分布在不同的地形上，包括山地（海拔高度超过400 m）、山麓（海拔高度在100 - 400 m之间）和平原（海拔高度在0 - 100 m之间）。高频率CIE区域的空间分布与MR-YRB内的山脉密切相关。即使在不稳定和垂直风切变较弱的条件下，山区经历的CIEs也是平原的两倍，尽管这些事件往往较小且持续时间较短。相比之下，山麓地区的对流面积最大。所有地形类型的CI频率均在中午（12:00-13:00 BJT）出现单峰，与最大热不稳定条件下的最高起始海拔（400-600 m）和最大对流面积一致。土壤水分（SM, 0-5 cm）和地表热通量（SHF）的非均质性可能在午间CIEs的触发中发挥关键作用。山地CIEs表现出最高程度的异质性。它们通常发生在SM比周围地区高的地区和靠近SHF增强的地区。较高的SM可能通过增加山地CI站点的低层水分和湿静态能为CI提供有利条件。明显的SM非均质性可能通过促进潜热或感热过程进一步促进CI，潜热或感热过程可以在明显的SM梯度附近产生中尺度热环流。

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来源期刊

Atmospheric Research 地学-气象与大气科学

CiteScore

9.40

自引率

10.90%

发文量

460

审稿时长

47 days

期刊介绍： The journal publishes scientific papers (research papers, review articles, letters and notes) dealing with the part of the atmosphere where meteorological events occur. Attention is given to all processes extending from the earth surface to the tropopause, but special emphasis continues to be devoted to the physics of clouds, mesoscale meteorology and air pollution, i.e. atmospheric aerosols; microphysical processes; cloud dynamics and thermodynamics; numerical simulation, climatology, climate change and weather modification.