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陈媛, 颜玲, 周玉淑, 等. 2022. 大渡河流域一次暴雪过程的天气环流特征及关键环境要素特征[J]. 气候与环境研究, 27(6): 778−786. doi: 10.3878/j.issn.1006-9585.2021.21177
引用本文: 陈媛, 颜玲, 周玉淑, 等. 2022. 大渡河流域一次暴雪过程的天气环流特征及关键环境要素特征[J]. 气候与环境研究, 27(6): 778−786. doi: 10.3878/j.issn.1006-9585.2021.21177
CHEN Yuan, YAN Ling, ZHOU Yushu, et al. 2022. Analysis on the Meteorological Causes and Environmental Characteristics of a Snowstorm Event in the Dadu River Basin [J]. Climatic and Environmental Research (in Chinese), 27 (6): 778−786. doi: 10.3878/j.issn.1006-9585.2021.21177
Citation: CHEN Yuan, YAN Ling, ZHOU Yushu, et al. 2022. Analysis on the Meteorological Causes and Environmental Characteristics of a Snowstorm Event in the Dadu River Basin [J]. Climatic and Environmental Research (in Chinese), 27 (6): 778−786. doi: 10.3878/j.issn.1006-9585.2021.21177

大渡河流域一次暴雪过程的天气环流特征及关键环境要素特征

Analysis on the Meteorological Causes and Environmental Characteristics of a Snowstorm Event in the Dadu River Basin

  • 摘要: 对2016年2月下旬大渡河流域的一次大到暴雪天气过程进行分析,通过天气环流特征分析和环境气象参数提炼,指出西路强冷空气爆发是大渡河流域上游大雪至暴雪的先导信号,这种信号可提前2~3 d。大雪的产生除了冷空气条件,也要有暖空气配合,对大渡河流域而言,最主要的暖湿空气来源有两条路径,一条是中层南支槽前暖湿气流北上在流域上游与冷空气相遇,形成高原切变线,是导致流域上游大到暴雪的主要中层天气系统。另一支暖湿气流沿横断山以东从低层进入四川盆地西北部地区,为流域降雪提供充足水汽条件。冷空气爆发后的适宜温度场,利于水汽升华变成雪花的过程。此次过程中,流域降大雪的温度条件可归纳为:700 hPa上气温不高于−5℃,500 hPa上气温不高于−9°C,地表温度低于0°C。在湿度指标上,环境大气相对湿度在70%以上,且空气中的水汽含量达到4 g kg1以上。

     

    Abstract: A heavy snowstorm process in the reaches of the Dadu River basin in late February 2016 was analyzed. Through synoptic diagnosis and environmental meteorological parameter refinement, it was revealed that a strong cold air outbreak is a precursor of heavy snowfall in the upper reaches of the Dadu River basin, which can be predicted 2–3 days in advance. The occurrence of a blizzard requires the cooperation of cold air with warm air. For the Dadu River basin, the primary moisture sources come from two paths: 1) The plateau shear line formed by a meeting of cold air with warm and wet air in front of the south trough, which is the dominant synoptic system at the middle level in the upper reaches of the Dadu River basin. 2) The warm and humid air stream that enters the northwestern part of the Sichuan Basin at a low level along the east of the Hengduan Mountains, providing sufficient water vapor conditions for snowfall in the region. The ascending motion driven by the dynamical configuration with convergence at the low level and divergence at the high level lifts the water vapor from the low level to the upper level. The water vapor then directly sublimates into snowflakes because of the cold environment, falling in the upper reaches of the Dadu River basin. The temperature and humidity conditions during this heavy snowstorm process can be summarized as follows: The temperature at 700 hPa is not higher than −5°C, the temperature at 500 hPa is not higher than −9°C, and the surface temperature is not higher than 0°C. The relative humidity of the ambient atmosphere is higher than 70%, and the moisture content in the air reaches above 4 g kg−1.

     

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