Journal of Arid Meteorology ›› 2020, Vol. 38 ›› Issue (2): 319-328.DOI: 10.11755/j.issn.1006-7639(2020)-02-0319

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Statistical Characteristics and Early Warning Indicators of Short-term Heavy Rainfall in the Loess Plateau of Qingyang

CHENG Peng1, LUO Han1, CHEN Peixuan2, CAO Yanchao3,LI Baozi1, CHEN Qi1   

  1. 1. Gansu Weather Modification Office, Lanzhou 730020, China;
    2. Lanzhou Regional Climate Center, Lanzhou 730020, China;
    3. Qingyang Meterological Bureau of Gansu Province, Lanzhou 745000, Gansu, China
  • Online:2020-04-28 Published:2020-04-28

庆阳黄土高原短时强降水统计特征及预警指标

程鹏1,罗汉1,陈佩璇2,曹彦超3,李宝梓1,陈祺1   

  1. 1.甘肃省人工影响天气办公室,甘肃 兰州 730020;
    2.兰州区域气候中心,甘肃 兰州 730020;
    3.甘肃省庆阳市气象局,甘肃 西峰 745000
  • 作者简介:程鹏(1981— ),男,甘肃临泽人,高级工程师,主要从事灾害性天气及人工影响天气研究. E-mail:tfreefish@163.com。
  • 基金资助:
    西北区域人影科学试验研究项目(RYSY201901)和甘肃省气象局气象科研项目(Ms2019-19)共同资助

Abstract: 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.

Key words: short-term heavy rainfall, physical quantity characters, early warning indicators, Loess Plateau

摘要: 利用2008—2018年自动气象站逐时降水量及雷达、探空资料,统计分析庆阳黄土高原地区短时强降水的时空分布、环境物理量及雷达回波特征。结果表明:(1)庆阳黄土高原北部和东南部是短时强降水高发区,北部环县和东南部正宁县是业务预报关注的重点区域。(2)短时强降水最早始于4月中旬,最晚止于10月中旬,集中发生在7—8月,7月中旬和8月中旬是两个高发时段,且“双峰型”日变化特征明显,主峰在17:00前后,次峰在09:00前后,16:00—18:00是不同量级短时强降水的高发时段。(3)短时强降水的水汽条件预警指标为700 hPa比湿不小于7 g·kg-1且T-Td≤4 ℃,能量条件预警指标为CAPE≥100 J·kg-1且CIN≤120 J·kg-1,不稳定条件预警指标为△T7-5≥15 ℃且SI≤1 ℃,特殊高度层预警指标为-20 ℃和0 ℃层高度平均分别为8.6 km和5.1 km,冻结层厚度△H平均为3.4 km。(4)雷达特征量预警指标为回波强度超过38 dBZ,回波顶高和最强回波中心高度分别超过7.0、3.6 km,VIL高于20 kg·m-2。经检验,这些预警指标可为庆阳黄土高原短时强降水的潜势预报和临近预警提供参考。

关键词: 短时强降水, 物理量特征, 预警指标, 黄土高原

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