ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Analysis of the formation mechanism and radar echo character-ristics of a severe storm in Southwest Yunnan in 2023
- Article
- Figures
- Metrics
- Preview PDF
- Reference
- Related
- Cited by
- Materials
Abstract:
Based on C-band weather radar products and multi-source observations, the persistent severe storm weather process and two major rainstorm monomers in southwest Yunnan was analyzed on 13-15 March 2023, and the results were as followed. The severe storm weather process occurred in the circulation background of the eastward retreat of the cold front on the ground, the establishment and intensification of the southwesterly rapids in the low (upper) air, and the persistent intrusion of the mid-level northwesterly flow, and the storm singletons mainly developed and intensified near the angle of the intersection of the mid- and high-altitude rapids. The continuous and stable transport of the low-level warm advection and the mid-level cold advection in southwest Yunnan intensifies the unstable stratification of the ambient atmosphere. The effective potential energy of convection is 826.6-1481.6 J·kg-1, the vertical wind shear from 0 to 3 km becomes 14.4-19.9 m·s-1, and that from 0 to 6 km becomes 27.6-34.5 m·s-1, and the unstable stratification of the high-level stratification and the strong shear environment are the main reasons for the development and maintenance of the catastrophic storms.The daytime storm was triggered by the coupling of southerly wind uplift forced by warm advection with weak surface convergence lines. The significant thermal and moisture contrast on either side of the Wuliang Mountains enhanced the storm"s development. In contrast, the nighttime storm initially formed near the mid-to-low-level baroclinic frontogenesis zone and was triggered by upslope lifting during its eastward movement, intensifying under the influence of the low-level southwesterly jet.Under the influence of diurnal variations and diverse topographic forcing, the radar echo characteristics of the storm cells exhibited distinct features. (1) Storm monomer No. 1 displayed radar echo morphologies such as an inflow notch, a bounded weak echo region (BWER), and a "V" notch, with radial velocity indicating a mesocyclone structure. During the hailfall period, the average composite reflectivity was 60.5 dBz, the average vertically integrated liquid (VIL) was 36.1 kg·m?2, and the average VIL density (VILD) was 4.0 g·m?3. In contrast, Storm monomer No. 2 exhibited a prominent rear-inflow jet (RIJ) and a forward-flank inflow notch (FIN), with more pronounced topographic responses in its echo, after crossing the Lancang River, the strong echo area, VIL, and VILD increased abruptly, with VILD rising from 1.7 g·m?3 to 4.5 g·m?3. (2) The life cycles and surface severe weather manifestations of the storm cells differed significantly. Cell 1 had a lifespan of 6 hours, accompanied by continuous hailfall during its influence period, with thunderstorm winds observed before and after its passage. The precipitation phase transitioned to a mix of hail and short-term heavy rainfall exceeding 20 mm·h?1 in the later stage. Cell 2 had a lifespan of 3 hours, with hailfall occurring only in the later stage of its development, and other types of convective weather were less intense.
Keywords:
Project Supported:
Clc Number:
Mobile website
