TY - JOUR
T1 - Numerical investigation of development processes of Baiu frontal depressions. Part II
T2 - An idealized study
AU - Tochimoto, Eigo
AU - Kawano, Tetsuya
N1 - Funding Information:
We would like to thank Profs. H. Itoh and R. Kawamura of Kyushu University, Prof. H. Niino and Dr. W. Yanase of the Atmosphere and Ocean Research Institute, the University of Tokyo, and Dr. A. Yamazaki of Japan Agency for Marine-Earth Science and Technology for their useful comments. We are grateful to Dr. T. Kato and two anonymous reviewers for their constructive comments. This work was supported by JSPS KAKENHI Grant Number 25400466.
PY - 2017
Y1 - 2017
N2 - In Part I of this study, the development processes of Baiu frontal depressions (BFDs) have been examined through case-study numerical experiments. The numerical simulations revealed that latent heating is dominant for the development of BFDs in the western part of the Baiu frontal zone (W-BFDs), west of approximately 140°E, while both latent heating and baroclinicity are important for the development of BFDs in the eastern part of the zone (E-BFDs), east of approximately 140°E. In this study, idealized numerical simulations with zonally homogeneous basic fields are conducted to obtain a more generalized perspective of the development processes of BFDs. The basic fields for the idealized simulations are made from the composites of the environments under which 28 W-BFDs and 43 E-BFDs developed. The idealized simulations successfully reproduce a realistic W-BFD and E-BFD. The W-BFD has a slightly westward-tilted vertical structure, modulated by latent heating at low levels of the atmosphere. In contrast, the E-BFD has a westward-tilted structure through the troposphere, similar to the well-known baroclinic wave structure. Results of available potential energy diagnosis for the effects of latent heating and baroclinicity on the BFD development are consistent with those in Part I. The W-BFD has a mechanism mainly driven by latent heating yielding strong convection, while the E-BFD develops through baroclinic instability in moist atmosphere.
AB - In Part I of this study, the development processes of Baiu frontal depressions (BFDs) have been examined through case-study numerical experiments. The numerical simulations revealed that latent heating is dominant for the development of BFDs in the western part of the Baiu frontal zone (W-BFDs), west of approximately 140°E, while both latent heating and baroclinicity are important for the development of BFDs in the eastern part of the zone (E-BFDs), east of approximately 140°E. In this study, idealized numerical simulations with zonally homogeneous basic fields are conducted to obtain a more generalized perspective of the development processes of BFDs. The basic fields for the idealized simulations are made from the composites of the environments under which 28 W-BFDs and 43 E-BFDs developed. The idealized simulations successfully reproduce a realistic W-BFD and E-BFD. The W-BFD has a slightly westward-tilted vertical structure, modulated by latent heating at low levels of the atmosphere. In contrast, the E-BFD has a westward-tilted structure through the troposphere, similar to the well-known baroclinic wave structure. Results of available potential energy diagnosis for the effects of latent heating and baroclinicity on the BFD development are consistent with those in Part I. The W-BFD has a mechanism mainly driven by latent heating yielding strong convection, while the E-BFD develops through baroclinic instability in moist atmosphere.
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U2 - 10.2151/jmsj.2017-012
DO - 10.2151/jmsj.2017-012
M3 - Article
AN - SCOPUS:85022191010
SN - 0026-1165
VL - 95
SP - 217
EP - 237
JO - Journal of the Meteorological Society of Japan
JF - Journal of the Meteorological Society of Japan
IS - 4
ER -