Study on the Characteristics of Low-level Jets in Short-term Heavy Rainfall under the Influence of Northeast Cold Vortex in Shenyang Based on Wind Profile Radar

DOI: https://doi.org/10.62517/jike.202404219

Author(s)

Weilong Ban, Xuan Zhao*, Yutong Wu, Shan Jiang

Affiliation(s)

Shenyang Meteorological Bureau, Shenyang, Liaoning, China *Corresponding Author.

Abstract

To enhance the understanding of the mechanisms behind heavy rainstorms influenced by the northeast cold vortex in Shenyang, we analyzed the intensity, height, and index of low-level jets during short-term heavy rainfall events from May to September between 2017 and 2021. The findings are as follows: (1) The maximum wind speed below 2 km generally follows a normal distribution, with low-level jets already present prior to approximately 30% of the heavy rainfall events. The maximum wind speed at corresponding percentiles shows a slight increase as the rainstorm approaches. However, the frequency of low-level jets decreases, and wind speeds significantly drop during the rainstorm. (2) The height distribution of low-level jets increases with altitude, reaching its lowest point 2 to 3 hours before the onset of heavy rainfall. At this time, low-level jets exhibit their strongest and most vigorous development. Combined with the warm, moist air from the southwest providing moisture and thermal energy, these conditions can trigger the onset of heavy rainstorms. (3) The hourly distribution of the low-level jet index (I) remains relatively consistent leading up to a rainstorm. As the rainstorm nears, wind speeds decrease, and the minimum height of low-level jets rises, resulting in a decrease in the low-level jet index (I).

Keywords

Northeast Cold Vortex; Wind Profile Radar; Short-term Heavy Rainfall; Threshold Selection; Low-level Jet

References

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