ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 49 Issue 7 > 2023,49(7):790-804. DOI:10.7519/j.issn.1000-0526.2023.032801 Prev Next
Doppler Radar Characteristics of Wide-Range Damaging Thunderstorm Gales in Shandong Province
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Abstract:
Based on multi-source observation data, the radar-echo characteristics of wide-range damaging thunderstorm gale events and the associated convective systems in Shandong Province and surrounding areas from 2005 to 2021 are analyzed. The results show that there were 41 wide-range damaging thunderstorm gale events in the 17 years, with an annual average frequency of 2.4 times, and they mainly occurred in June. Before the occurrence of damaging thunderstorm gale, there tends to be remarkable conditional instability and moderate-to-slight humidity condition in the middle and lower troposphere. Meanwhile, there is a prominent dry layer in the middle level, and the vertical wind shear is moderate-to-slightly strong. The convective systems that lead to wide-range damaging thunderstorm gales can be divided into four categories: type Ⅰ squall line (cell resolvable type), type Ⅱ squall line (banded-echo type), multicell storm cluster and weak echo squall line. The rear inflow jet carries dry-cold air into the squall line and enhances the negative buoyancy through evaporative cooling effect, which is an important formation mechanism of damaging thunderstorm gale generated by type Ⅰ and type Ⅱ squall lines. The backward (or rightward) propagating multicell storm clusters all contain supercells, whose gust front can both produce damaging thunderstorm gale and trigger new storms. Due to the fast moving speed of the severe storm and the possibly-existing rear inflow jet, as well as the downward transport of momentum from high levels caused by the downdraft in the precipitation, the asymmetric downburst can occur, which increases the possibility of extreme thunderstorm gales.The damaging thunderstorm gales generated by the weak echo squall lines are most likely to be ignored. The convective subsystems that directly cause damaging gales can be classified into five categories, namely bow echo, strong single cell storm, supercell storm, gust front and mixed type, accounting for 30%, 26%, 6%, 23% and 16%, respectively. The average values of the maximum wind speed caused by bow echo and supercell are the largest, reaching 28.2 m·s-1 and 29.9 m·s-1 respectively. The formation of bow echo can be predicted about 20 minutes in advance according to strong rear inflow jet and remarkable mid altitude radial convergence (MARC). The damaging thunderstorm gale mainly occurs in the central and left parts of the bow echo relative to its moving direction. Extreme thunderstorm gales with wind speed over 32.6 m·s-1 are generated by the line-echo wave pattern embedded with bow echoes, the combination of bow echo and mesoscale vortex, and supercells. Thunderstorm gales at the speed about 30 m·s-1 can be produced by the strong single cell storms with deep MARC, the gust fronts in strongly developed squall lines, and the superposition of surface cold front and gust front which is often accompanied by downward momentum transportation.
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P446,P458
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