Moisture Sources and Quantitative Contribution Analysis of the7·22Heavy Rainstorm in Gansu Province

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  • 1. Lanzhou Central Meteorological ObservatoryLanzhou 730020GansuChina
    2. Jiuquan Meteorological Bureau of Gansu ProvinceJiuquan 735000GansuChina
    3. Heavy Rain and Drought - Flood Disasters in Plateau and Basin Key Laboratory of Sichuan ProvinceChengdu 610072SichuanChina

Online published: 2025-05-08

Abstract

Based on automatic weather station observations of precipitationERA5 reanalysis data and NCEP GDAS datathrough methods such as water vapor budget analysisHYSPLIT backward trajectory tracking and water vapor transport contribution ratethis paper analyzed the water vapor transport characteristics of a severe rainstorm event that occurred in the southeastern part of Gansu Province from July 22 to 242024and quantitatively discussed its water vapor source and contribution rate. The results showed that the rainstorm area was located in the exit zone of the upper-level jet streamwhere the airflow divergence enhanced the vertical transport of low-level water vaporcausing the moist layer deeper. The continuous synergic influence of Typhoon " Prapiroon" and the subtropical high transported water vapor over the South China Sea and the Bay of Bengal to the rain‐ storm areaproviding sufficient water vaporand the rainstorm area maintained a significant near-surface wet area and high precipitable water. The results of water vapor budget and tracking analysis showed that the inflow of water vapor mainly occurred at the southern boundary of 800~500 hPawith a maximum inflow of 1237 kg·m-·1 s-1. Before the rainstormthe water vapor mainly originated from the South China Sea and the Bay of Bengaland the water vapor channels accounted for 48% and 42% of all tracks respectivelyand the water vapor transport contribution rate was 51. 45% and 43. 31% respectively. When the rainstorm occurredwater vapor mainly originated from the South China Seaits water vapor channels accounted for 53% of all the tracksand the contribution rate of water vapor transport was 57. 98%. In additionthe water vapor transport in the Western Pacific and Northwest Passage also contributed to the rainstorm. This would be conducive to understanding the formation mechanism of the extraordinary rainstorm in Northwest Chinaand provided certain references for the future forecast of extraordinary rainstorm in Gansu Province.

Cite this article

HUANG Yuxia, FAN Qiwei, WANG Yong, GUO Runxia, LI Wenyao . Moisture Sources and Quantitative Contribution Analysis of the7·22Heavy Rainstorm in Gansu Province[J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00053

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