关键词: 典型强降雨, 大气可降水量, 演变特征, 对比分析

Abstract:

Based on conventional ground observations and high-altitude radiosonde, hourly precipitation data of 123 automatic meteorological stations in Shandong Province and atmospheric precipitable water monitored by 25 ground-based GPS, the variation characteristics of atmospheric precipitable water vapor (PWV) during typical heavy rain processes under different weather systems were analyzed. The results are as follows: (1) The time length of water vapor accumulation before the rain was closely related to the spatio-temporal scale of weather systems. Usually, the larger the weather system scale is, the longer the accumulation time is. The water vapor accumulation time before heavy rain for cold-front and trough type was about 26 hours and it was only 5-6 hours before the beginning of heavy rain on the edge of Western Pacific Subtropical High (WPSH). (2) The growth rate of PWV was also closely related to weather system scale. The rate was less than 2.0 mm·h-1 in front of cold-front heavy rain case and about 3.1 mm·h-1  for the heavy rain on the edge of WPSH. (3) The water vapor accumulation time before the heavy rain was inversely related to the water vapor growth rate. When water vapor growth rate was more than 2.0 mm·h-1, it took only 5-6 hours for water vapor accumulation before the heavy rain. (4) The beginning of heavy rain usually coincided with peak period of PWV. The heavy rain on the edge of WPSH was associated with increasing of the water vapor accumulation, which was similar to the first stage of the heavy rain caused by cold shear line. The PWV often decreases sharply after the rain. However, it increased after the rain on the edge of WPSH and during the first stage of the cold shear line type. After the second stage of the cold shear line heavy rain, the PWV decreased slightly. Moreover, the PWV increased a few hours after the rain again.

Key words: typical severe rainfall, precipitable water vapor, evolution characteristics, contrast analysis