Synoptic-scale physical mechanisms associated with the Mei-yu front: A numerical case study in 1999

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°E. To further understand the synopticscale physical mechanisms associated with the Mei-yu front system, the present study proposes another insight into the physical significance 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 dewpoint 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 Meiyu 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.

This is a preview of subscription content, log in to check access.

References

  1. Bluestein, H. B., 1993: Synoptic-dynamic meteorology in midlatitudes, Vol.2, Oxford University Press, 594 pp.

  2. Chang, C.-P., L. Yi, and G. T.-J. Chen, 2000: A numerical simulation of vortex development during the 1992 East Asian summer monsoon onset using the Navy’s regional model. Mon. Wea. Rev., 128, 1604–1631.

    Article  Google Scholar 

  3. Chen, G. T.-J., and C.-P. Chang, 1980: The structure and vorticity budget of an early summer monsoon trough (Mei-Yu) over southeastern China and Japan. Mon. Wea. Rev., 108, 942–953.

    Article  Google Scholar 

  4. —, C.-C. Wang, and S.-W. Chang, 2008: A diagnostic case study of Mei-yu frontogenesis and development of wavelike frontal disturbances in the subtropical environment. Mon. Wea. Rev., 136, 41–61.

    Article  Google Scholar 

  5. —, —, and L.-F. Lin, 2006: A diagnostic study of a retreating Mei-yu front and the accompanying low-level jet formation and intensification. Mon. Wea. Rev., 134, 874–896.

    Article  Google Scholar 

  6. —, —, and S.C-S. Liu, 2003: Potential vorticity diagnostics of a Mei-yu front case. Mon. Wea. Rev., 131, 2680–2696.

    Article  Google Scholar 

  7. Chen, G. T.-J., C.-C. Wang, and A.-S. Wang, 2007: A case study of subtropical frontogenesis during a blocking event. Mon. Wea. Rev., 135, 2588–2609.

    Article  Google Scholar 

  8. Chien, F.-C., Y.-H. Kuo, and M.-J. Yang, 2002: Precipitation forecast of MM5 in the Taiwan area during the 1998 Mei-yu season. Wea. Forecasting, 17, 739–754.

    Article  Google Scholar 

  9. Cho, H.-R., and G. T.-J. Chen, 1995: Mei-yu frontogenesis. J. Atmos. Sci., 52, 2109–2120.

    Article  Google Scholar 

  10. Cotton, W. R., and Coauthors, 2003: RAMS 2001: Current status and future directions. Meteor. Atmos. Phys., 82, 5–29.

    Article  Google Scholar 

  11. Davies-Jones, R., 1991: The frontogenetical forcing of secondary circulations. Part I: The duality and generalization of the Q vector. J. Atmos. Sci., 48, 497–509.

    Article  Google Scholar 

  12. Ding, Y., and J. C. L. Chan, 2005: The East Asian summer monsoon: An overview. Meteor. Atmos. Phys., 89, 117–142.

    Article  Google Scholar 

  13. Holton, J. R., 2004: An introduction to dynamic meteorology. 4th Edition. Academic Press, 535 pp.

  14. Jung, J.-H., and A. Arakawa, 2008: A three-dimensional anelastic model based on the vorticity equation. Mon. Wea. Rev., 136, 276–294.

    Article  Google Scholar 

  15. Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77, 437–471.

    Article  Google Scholar 

  16. Kawatani, Y., and M. Takahashi, 2003: Simulation of the Baiu front in a High Resolution AGCM. J. Meteor. Soc. Japan, 81, 113–126.

    Article  Google Scholar 

  17. Lau, K.-M., G. J. Yang, and S.H. Shen, 1988: Seasonal and intraseasonal climatology of summer monsoon rainfall over East Asia. Mon. Wea. Rev., 116, 18–37.

    Article  Google Scholar 

  18. Ninomiya, K., and Y. Shibagaki, 2007: Multi-scale features of the Meiyu-Baiu front and associated precipitation systems. J. Meteor. Soc. Japan, 85, 103–122.

    Article  Google Scholar 

  19. Pielke Sr., R. A., 2002: Mesoscale Meteorological Modeling (2 nd edition). Academic Press. 676 pp.

  20. —, and Coauthors, 1992: A comprehensive meteorological modeling system RAMS. Meteor. Atmos. Phys., 49, 69–91.

    Article  Google Scholar 

  21. Qian, J.-H., W.-K. Tao, and K.-M. Lau, 2004: Mechanisms for torrential rain associated with the Mei-yu development during SCSMEX 1998. Mon. Wea. Rev., 132, 3–27.

    Article  Google Scholar 

  22. Reynolds, R. W., N. A. Rayner, T. M. Smith, D. C. Stokes, and W. Wang, 2002: An improved in situ and satellite SST analysis for climate. J. Climate, 15, 1609–1625.

    Article  Google Scholar 

  23. Sampe, T., and S-P. Xie, 2010: Large-scale dynamics of the Meiyu-Baiu rainband: Environmental forcing by the westerly jet. J. Climate, 23, 113–134.

    Article  Google Scholar 

  24. Shen, X., M. Kimoto, A. Sumi, A. Numaguti, and J. Matsumoto, 2001: Simulation of the 1998 East Asian summer monsoon by the CCSR/NIES AGCM. J. Meteor. Soc. Japan, 79, 741–757.

    Article  Google Scholar 

  25. Shibagaki, Y., and K. Ninomiya, 2005: Multi-scale interaction processes associated with development of a sub-synoptic-scale depression on the Meiyu-Baiu frontal zone. J. Meteor. Soc. Japan, 83, 219–236.

    Article  Google Scholar 

  26. Stonitsch, J. R., and P. M. Markowski, 2007: Unusually long duration, multiple-Doppler radar observations of a front in a convective boundary layer. Mon. Wea. Rev., 135, 93–117.

    Article  Google Scholar 

  27. Truong, N. M., T. T. Tien, R. A. Pielke Sr., C. L. Castro, and G. Leoncini, 2009: A modified Kain-Fritsch scheme and its application for simulation of an extreme precipitation event in Vietnam. Mon. Wea. Rev., 137, 766–789.

    Article  Google Scholar 

  28. Walko, R. L., W. R. Cotton, M. P. Meyers, and J. Y. Harrington, 1995: New RAMS cloud microphysics parameterization. Part I: The single moment scheme. Atmos. Res., 38, 29–62.

    Article  Google Scholar 

  29. Wang, B., 1987: The development mechanism for Tibetan Plateau warm vortices. J. Atmos. Sci., 44, 2978–2994.

    Article  Google Scholar 

  30. Wang, Y., O. L. Sen, and B. Wang, 2003: A highly resolved regional climate model (IPRC-RegCM) and its simulation of the 1998 severe precipitation event over China. Part I: Model description and verification of simulation. J. Climate, 16, 1721–1738.

    Article  Google Scholar 

  31. Yanai, M., and G-X. Wu, 2006: Effects of the Tibetan plateau. The Asian monsoon, Springer. Praxis Publishing, 513–549.

  32. Yasunari, T., and T. Miwa, 2006: Convective cloud systems over the Tibetan Plateau and their impact on meso-scale disturbances in the Meiyu/Baiu frontal zone: A case study in 1998. J. Meteor. Soc. Japan, 84, 783–803.

    Article  Google Scholar 

  33. Yoshikane, T., F. Kimura, and S. Emori, 2001: Numerical study on the Baiu front genesis by heating contrast between land and ocean. J. Meteor. Soc. Japan, 79, 671–686.

    Article  Google Scholar 

  34. Zhang, Q.-H., K.-H. Lau, Y.-H. Kuo, and S.-J. Chen, 2003: A numerical study of a mesoscale convective system over the Taiwan strait. Mon. Wea. Rev., 131, 1150–1170.

    Article  Google Scholar 

  35. Zhou, Y., S. Gao, and S. S. P Shen, 2004: A diagnostic study of formation and structures of the Meiyu front system over East Asia. J. Meteor. Soc. Japan, 82, 1565–1576.

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Nguyen Minh Truong.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Truong, N.M., Hang, V.T., Pielke, R.A. et al. Synoptic-scale physical mechanisms associated with the Mei-yu front: A numerical case study in 1999. Asia-Pacific J Atmos Sci 48, 433–448 (2012). https://doi.org/10.1007/s13143-012-0039-x

Download citation

Key words

  • Mei-yu frontogenesis
  • frontolysis
  • twisting effect
  • atmospheric buoyancy
  • ageostrophic twisting effect