关键词: 强降雨, Z-R关系, 单体演变

Abstract:

Based on the observations of automatic meteorological stations and Doppler radar data, the precipitation intensity, Z-R relationship, storm parameters and radar morphological characteristics of rainstorms with hourly rainfall more than 80 mm for 31 stations during 2014-2016 in Shandong Province were analyzed. The results show that larger convective available potential energy (CAPE>500 J·kg-1), higher K index (K≥33 ℃) and lower lifted index (LI≤-2 ℃), and larger specific humidity (q≥13 g·kg-1) at lower level were important factors resulting in hourly extreme rainfall. The evolution of heavy rainfall storms had “train effect” or slow moving characteristics. There were 15 storms with the characteristic of “train effect” and 8 storms with slow moving characteristic, 8 storms with both two features. The rainfall duration was about 57-58 minutes, the maximum rainfall of 5 minutes and 6 minutes was about 15 mm and 17 mm, respectively. Regarded the average value (17.3 mm) of 6 minutes maximum rainfall as strong precipitation intensity, the corresponding average value of reflectivity factor was 50.3 dBZ, the relationship between precipitation intensity and reflectivity factor fitted with the formula of Z=200 R1.22. In summer season, the maximum reflectivity factor of heavy rainstorms was between 50 and 59 dBZ, the vertically integrated liquid content ranged basically from 15 to 40 kg·m-2, the height of strong echo center was basically below the height of 0 ℃ layer, the top height of storm cell was above 8 km, the echo top height was above 11 km, the precipitation efficiency was higher，and Z-R relationship were approximated to Z=200 R1.22.

Key words:  heavy rain, Z-R relationship, storm evolution