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Title: Synoptic-Scale Physical Mechanisms Associated with the Mei-yu Front: A Numerical Case Study in 1999
Authors: Nguyen Minh Truong
Vu Thanh Hang
Roger A. Pielke Sr.
Christopher L. Castro
Koji Dairaku
Keywords: Mei-yu frontogenesis;frontolysis;twisting effect;atmospheric buoyancy;ageostrophic twisting effect
Issue Date: 2012
Abstract: The Mei-yu front system occurring from 23 to 27 June 1999 consists of the Mei-yu front and the dewpoint front, which confine a warm core extending from the eastern flank of the Tibetan Plateau to the west of 145 o E. To further understand the synoptic-scale physical mechanisms associated with the Mei-yu front system, the present study proposes another insight into the physical signifi-cance of the x-component relative vorticity (XRV) whose vertical circulation is expected to tilt isentropic surfaces. The XRV equation diagnoses exhibit that the twisting effect of the planetary vorticity (TEPV) is positive along the Mei-yu front and negative in the dew-point front region, and tilts isentropic surfaces from south to north in the Mei-yu frontal zone. Conversely, the meridional gradient of the atmospheric buoyancy (MGAB) tilts isentropic surfaces in the opposite direction and maintains negative in the regions where the TEPV is positive and vice versa. Thus, the TEPV plays the role of the Mei-yu frontogenesis, whereas the MGAB demonstrates the Mei-yu frontolysis factor. Both terms control the evolution of the cross-front circulation. The other terms show much minor contributions in this case study. The present simulations also indicate that the weakening of the upper-level jet evidently induces the weakening of the Mei-yu front and reduces the amplitude of the East Asia cold trough. Furthermore, the impact can also penetrate into the lower troposphere in terms of mesoscale disturbances and precipitation, proving that the upper-level jet imposes a noticeable top-down influence on the Mei-yu front system.
Description: TNS06795; ASIA-PACIFIC JOURNAL OF ATMOSPHERIC SCIENCES Volume: 48 Issue: 4 Pages: 433-448 Published: NOV 2012
ISSN: ISSN: 1976-7633
Appears in Collections:Bài báo của ĐHQGHN trong Web of Science

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