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云南小时极端降水时空变化特征与城市化效应

Spatiotemporal Characteristics of Hourly Extreme Precipitation and the Effects of Urbanization in Yunnan, China

  • 摘要: 基于云南省125个国家气象站1980~2022年和1135个区域气象站2010~2022年的逐小时降水观测数据以及社会经济、土地利用和夜间灯光等数据,采用99.9%分位的小时极端降水阈值来界定小时极端降水事件,研究了云南复杂地形条件下小时极端降水的时空变化特征及城市化效应。结果表明:云南小时极端降水指数分布南部边缘最高,而滇西北地区则相对较低;极端降水贡献率呈现高集中度分布特征,中东部地区的贡献率最高,超过19%;日变化呈现出双峰形态,高峰期分别出现在17:00(北京时间,下同)至20:00和02:00-05:00,谷值期出现在11:00-14:00;小时极端降水贡献率和降水频次的高值均出现在夏季,贡献率超过20%,7~8月的小时极端降水频次高达2.0次。相比于1980~2022年,2010~2022年的小时极端降水指数的日变化和月变化均增加,夏季极端降水的频次和贡献率也更加集中。对城市化进程影响小时极端降水的研究发现,在城市化缓慢发展的1980~2006年,城市站点小时极端降水指数的增加速率略高于同期郊县站点;而在快速发展的2007~2022年,城市站的小时极端降水指数增长速度是郊县站的2~3倍;快速发展阶段小时极端降水指数的日变化和月变化强度均高于缓慢发展阶段。研究成果为深入理解复杂地形区域极端降水提供了科学依据,并为高原城市气候风险防控与适应性规划提供了重要支持。

     

    Abstract: . Hourly extreme precipitation (HEP) events were defined using the 99.9% percentile threshold, and the spatiotemporal characteristics and the effects of urbanization on HEP under complex terrain conditions in Yunnan were investigated by using hourly precipitation data from 125 national meteorological observation stations for 1980–2022 and 1135 regional stations for 2010–2022 in Yunnan, along with socioeconomic, land-use, and nighttime lighting data. The results show that the distribution of the HEP index was the highest in the southern border region, whereas it was relatively low in the northwestern region in Yunnan. The highest HEP contribution rate, exceeding 19%, was observed in central and eastern Yunnan. The characteristics of HEP daily variation indicate a bimodal pattern, with peak periods at 17:00–20:00 and 02:00–05:00, and valley periods at 11:00–14:00. The high HEP contribution rate and frequency occur in summer, with a contribution rate exceeding 20%. The HEP frequency in July and August reached 2.0 times. Compared with those during 1980–2022, the daily and monthly variations of the HEP index were stronger during 2010–2022, and the frequency and contribution rate in summer were more concentrated. The analysis of the impact of urbanization on HEP revealed that during the period of slow urbanization in 1980–2006, the increase in the HEP index at urban stations was slightly higher than at suburban stations. However, during the rapidly developing period of 2007–2022, the HEP index increase rate of urban stations was 2–3 times that of suburban stations. The daily and monthly variations of the HEP index during the rapid development stage were higher than during the slow development stage. These results offer a scientific basis for a deeper understanding of how HEP characteristics change under complex terrain conditions and provide important support for climate risk prevention and adaptive planning in cities in the plateau region.

     

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