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Archive > Volume 48 Issue 12 > 2022,48(12):1550-1564. DOI:10.7519/j.issn.10000526.2022.033101 Prev Next

Comparison of Two Rainstorms Related to Distant Typhoons Affecting Jiangsu Province During Meiyu Period

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    Abstract:
    A comparison of two rainstorms that ocurred in June 2001 and July 1986 (hereafter “01·6” and “86·7”) related to distant typhoons affecting Jiangsu 〖JP2〗Province during Meiyu period shows that for “01·6”,〖JP〗 the precipitation duration is shorter, the precipitation area is not changed, and the rainfall intensity is stronger, while for “86·7”, the precipitation duration is longer, the precipitation area moves from north to south, and the rainfall intensity is weaker. In terms of atmospheric circulations, during the “01·6” process, the subtropical high extends significantly to the north, the northward extending inverted trough of typhoon and the lowlevel jet jointly form the lowlevel convergence and transport the warm and moist air together, the lowpressure troughs at middle and upperlevel are stable, and the influence of upperlevel cold air is weaker. Comparatively during the “86·7” process, the northward extension and impact of typhoon’s inverted trough are weaker， the convergence of lowlevel wind and the transportation of warm and humid air flow rely more on lowlevel jet than on the inverted trough of typhoon, the lowpressure troughs at middle and upper level both move eastward and southward quickly, and the influence of upperlevel cold air is strong. In terms of dynamical analysis, the highlevel divergence and lowlevel convergence of the “01·6” process are more intense, the coupling of positive vorticity at lower level and negative vorticity at upper level is more stable and deep, the nongeostrophic wet 〖WTHX〗Q〖WT5BZ〗 vector convergence is stronger, and all these dynamic processes stay over the southeastern part of Jiangsu. However, for “86·7”, the dynamic processes are weaker, the coupling of divergence and vertical vorticity move from northcentral Jiangsu to the southeastern part of Jiangsu, and the nongeostrophic 〖WTHX〗Q〖WT5BZ〗 vector convergence zone covers eastern part of Jiangsu. Compared with “86·7”, the lowlevel water vapor flux convergence of “01·6” is stronger, the air over the rainstorm area of “01·6” is more saturated, and the deep saturated layer “01·6” is formed earlier and maintain longer. In terms of thermodynamical analysis, the convective instability of middle and lowerlevel atmosphere is stronger, but the E index and its increment of “01·6” are greater, which demonstrates that the middle 〖JP2〗and lowlevel atmosphere contains more energy and more water vapor.

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