|
Statistical Characteristics and Early Warning Indicators of Short-term Heavy Rainfall in the Loess Plateau of Qingyang
CHENG Peng, LUO Han, CHEN Peixuan, CAO Yanchao, LI Baozi, CHEN Qi
Journal of Arid Meteorology
2020, 38 (2):
319-328.
DOI: 10.11755/j.issn.1006-7639(2020)-02-0319
Based on the hourly precipitation from automatic weather stations, radar data at Xifeng station and radiosonde data at Pingliang station from 2008 to 2018, the temporal and spatial distribution, physical quantities and radar echo characteristics of short-term heavy rainfall in the Loess Plateau of Qingyang were analyzed statistically. The results are as follows: (1) The short-term heavy rainfall was easily to occur in the north and southeast of the Loess Plateau of Qingyang, and the business forecast should focus in Huan county and Zhengning county. (2) The earliest and latest short-term heavy rainfall occurred in mid-April and mid-October in the Loess Plateau of Qingyang from 2008 to 2018, respectively, and it occurred mostly in July and August, the peaks were in mid-July and mid-August. The diurnal variation of short-term heavy rainfall appeared typical double peaks pattern, the major and minor peaks occurred at about 17:00 BST and 09:00 BST, respectively, and the frequency of short-term heavy rainfall with different levels was higher from 16:00 BST to 18:00 BST. (3) The early warning indicators of water vapor condition of short-term heavy rainfall were 700 hPa specific humidity equal to or more than 7 g·kg-1 and temperature dew-point difference equal to or less than 4 ℃ in the Loess Plateau of Qingyang, as to energy condition, CAPE was equal to or more than 100 J·kg-1 and CIN was equal to or less than 120 J·kg-1, and for instability condition, △T7-5 was equal to or more than 15 ℃ and SI was equal to or less than 1 ℃. In addition, the early warning indicators of -20 ℃ and 0 ℃ layers height averaged 8.6 km and 5.1 km, and the thickness of frozen layer averaged 3.4 km. (4) The radar echo intensity of short-term heavy rainfall exceeded 38 dBZ, the height of echo top and the strongest echo center were more than 7.0 km and 3.6 km, respectively, and the VIL was more than 20 kg·m-2, which could be used for early warning indicators of short-term heavy rainfall. Upon inspection, these early warning indicators could provide some useful references for potential forecast and nowcasting of short-term heavy rainfall in the Loess Plateau of Qingyang.
Related Articles |
Metrics
|
|