Numerical investigation of development processes of Baiu frontal depressions part I: Case studies

Eigo Tochimoto, Tetsuya Kawano

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Abstract

This work investigates the development processes of Baiu frontal depressions (BFDs) using a numerical model. To investigate the effects of upper-level disturbances, latent heating, and baroclinicity on the development of BFDs, case-study numerical simulations are performed. In the present study, two typical cases were selected from BFDs that appeared in June and July, 2000-2007-a BFD that developed in the western part of the Baiu frontal zone (W-BFD) from 26 to 27 June, 2003, and a BFD that had formed in the eastern part of the Baiu frontal zone (E-BFD) from 1 to 3 July, 2003. An available potential energy diagnosis shows that the effect of latent heating is dominant during the W-BFD development, while baroclinicity as well as latent heating is important to the E-BFD development. A sensitivity experiment excluding upper-level potential vorticity (PV) anomalies shows that upperlevel disturbances are important contributors to the development of E-BFDs. The low-level PV and its production associated with latent heating suggest that the W-BFD has a development mechanism driven by latent heating. In the early developmental stage, PV near the W-BFD center is enhanced. This feature is consistent with the nonlinear conditional instability of the second kind mechanism. In the later developmental stage, PV is produced in front of the W-BFD center, in which low-level baroclinicity is large. This process is consistent with a diabatic Rossby vortex. In contrast, the E-BFD develops through a baroclinic instability- like mechanism in the moist atmosphere.

Original languageEnglish
Pages (from-to)91-109
Number of pages19
JournalJournal of the Meteorological Society of Japan
Volume95
Issue number2
DOIs
Publication statusPublished - Jan 1 2017

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potential vorticity
heating
developmental stage
disturbance
baroclinic instability
potential energy
vortex
anomaly
atmosphere
simulation
experiment
effect

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

Numerical investigation of development processes of Baiu frontal depressions part I : Case studies. / Tochimoto, Eigo; Kawano, Tetsuya.

In: Journal of the Meteorological Society of Japan, Vol. 95, No. 2, 01.01.2017, p. 91-109.

Research output: Contribution to journalArticle

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