[A-AS05] Large-scale moisture and organized cloud systems

[AAS05-09] Structure and life cycle of the mesoscale convective system in the
Baiu Frontal Zone over the East China Sea observed on June 19, 2022

*ATSUYOSHI MANDA¹, Yoshihiro Tachibana¹, Hirohiko Nakamura², Tetsutaro Takikawa³, Ayako Nishina², Qoosaku Moteki⁴, Satoshi Iizuka⁵ (1.Mie University, 2.Kagoshima University, 3.Nagasaki University, 4.JAMSTEC, 5.NIED)

Keywords:water vapor flux, In-situ observation, entrainment

The present study investigates the development of the mesoscale
convective system (MCS) that occurred in the Baiu frontal zone near
the northern edge of the Kuroshio (30-31N, 128-129E) on June 19, 2022.
A combination of the multi-vessel high-frequency atmospheric soundings
and objective analysis data was used to analyze the MCS. The intense
precipitation exceeding 100 mm/3-hr persisted for approximately 6
hours from 00 to 06 UTC on 19 June in the MCS. On 18 June before the
precipitation intensified, the water vapor flux convergence zones at
the surface and at 850 hPa level were separated meridionally by
approximately 200 km. A weak precipitation area (< 10 mm/3-hr) was
broadly distributed north of the surface front. Due to the rapid
northward migration of the surface front, the northern edge of the
convectively unstable southerly winds overlapped the 850-hPa water
vapor flux convergence region. The precipitation intensified
accordingly. The precipitation weakened after 06 UTC on June 19 when
the northeastward migration of the water vapor flux convergence zone
at 850 hPa level became faster than that of the surface front. It is
suggested that convectively unstable southerly winds near the surface
and water vapor flux convergence associated with southwesterly winds
near 850 hPa level were important for the rapid development of the
observed MCS.