京津冀及周边一般性降水与短时强降水特征对比

Comparison of Characteristics of Light Precipitation and Short-time Heavy Precipitation over Beijing, Tianjin, Hebei and Neighbouring Areas

  • 摘要: 京津冀及周边地区为我国北方强降水的多发区域。基于1966—2021年87个国家级气象站逐小时降水资料对比分析暖季5—9月一般性降水和短时强降水的空间分布及年际变化,并基于1980—2021年298个气象站分析日变化等特征。结果表明:京津冀及周边地区的渤海西侧平原区域存在短时强降水强度极端性显著区域。渤海西侧平原以外区域两类降水平均小时降水量、强度和降水时次百分比均呈增长趋势,但短时强降水的增幅更高,而渤海西侧平原区域趋势则均不明显。渤海西侧平原区域和渤海西侧平原以外区域的一般性降水平均小时降水量和降水时次百分比日变化幅度显著弱于短时强降水;7—9月渤海西侧平原区域降水夜发性更明显,且相比另一区域半峰持续时间多出约2 h。2005年后渤海西侧平原区域和渤海西侧平原以外区域短时强降水平均小时降水量和降水时次百分比下午时段均明显减弱,但午夜后至清晨明显增加。

     

    Abstract: Beijing, Tianjin, Hebei and neighbouring areas (34°-43°N, 113°-123°E) are located at the north edge of the East Asian summer monsoon, and they are also the main heavy-rain areas in northern China. The hourly precipitation data of 87 national meteorological stations from 1966 to 2021 are used for the analysis of spatial distribution and interannual variations, while the data of 298 stations from 1980 to 2021 are used to statistically analyze the diurnal variations and interannual variations of light precipitation (0.1-20 mm·h-1) and short-time heavy precipitation (no less than 20 mm·h-1) for the warm season (May-September) over the region. The results show that the annual average light precipitation and frequency in Beijing, Tianjin, Hebei and neighbouring areas during the warm season are much higher than those of short-time heavy precipitation. However, there is an area in the west of the Bohai Sea Region (37°-41°N, 115°-119.5°E) with high short-time heavy rainfall intensity but weak rainfall amount and frequency, which means the convective characteristics of short-time precipitation over this area are more extreme and significant. The interannual variations of two kinds of precipitation amount, frequency, and intensity in Beijing, Tianjin, Hebei and neighbouring areas excluding the west of Bohai Sea Region both present an overall growing trend in the warm season, in which the increasing trend of short-time heavy precipitation is more obvious, but the trend in the west of the Bohai Sea Region is not obvious. The diurnal variation amplitudes of light precipitation amount and frequency in Beijing, Tianjin, Hebei and neighbouring areas excluding the west of the Bohai Sea Region are significantly weaker than those of short-time heavy precipitation, but the peak durations are significantly longer. Compared to Beijing, Tianjin, Hebei and neighbouring areas excluding the west of the Bohai Sea Region, two types of precipitation in the west of the Bohai Sea Region from July to September are more frequent and the rainfall peak durations are longer. The interannual variations of precipitation in different periods of the whole day show that the light precipitation in two regions both decrease in the afternoon, while the short-time heavy precipitation has weakened significantly in the afternoon since 2005, but increased significantly from midnight to early morning.

     

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