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High Temporal‐Spatial Resolution Observation of Tornadogenesis in a Shallow Supercell Associated With Typhoon Hagibis (2019) Using Phased Array Weather Radar
Author(s) -
Adachi Toru,
Mashiko Wataru
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl089635
Subject(s) - mesocyclone , supercell , vortex , typhoon , geology , tornado , clockwise , meteorology , outflow , climatology , physics , doppler radar , oceanography , doppler effect , amplitude , astronomy , quantum mechanics
This paper reports finely resolved radar signatures of tornadogenesis associated with a typhoon and elucidates how a small‐scale tornadic vortex emerged on the ground in relation to the parent storm structure. Approximately 5 min before producing JEF‐2 damage, a counterrotating vortex pair appeared above the rear‐flank outflow region. The vortex pair developed upward, and its counterclockwise vortex approached a preexisting mesocyclone located aloft. At their closest approach, an abrupt intensification of the counterclockwise vortex occurred in the upper part and propagated downward. Meanwhile, significant vortex shrinking occurred at low levels. As a result, a small‐scale tornadic vortex emerged over the damaged area. We suggest that coupling of the vortex pair with a mesocyclone and near‐surface vorticity stretching played crucial roles in tornadogenesis. Since the coupling occurred on a minute scale and was affected by subtle spatial change on a scale of hundreds of meters, the tornado occurred in highly sensitive conditions.