The Role of Offshore Convergence on Coastal Rainfall during TAMEX IOP 3

Hsi-Chyi Yeh Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii

Search for other papers by Hsi-Chyi Yeh in
Current site
Google Scholar
PubMed
Close
and
Yi-Leng Chen Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii

Search for other papers by Yi-Leng Chen in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The role of offshore convergence on the coastal rainfall maximum along the northwestern coast of Taiwan is analyzed based on TAMEX (Taiwan Area Mesoscale Experiment) data and numerical experiments using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5).

From a case study during TAMEX IOP 3, moderate rainfalls (∼40 mm h–1) are observed along the northwestern coast of Taiwan associated with the arrival of three rainbands in succession during 1000–1600 LST. These rainbands form over the Taiwan Strait with northeast–southwest or north–south orientation. They intensify off the northwestern coast. There is a tendency for the most intense echoes to align in a northeast–southwest orientation off the northwestern coast. An orographically enhanced convergence zone with a northeast–southwest orientation occurs in the area where the deflected southerly flow converges with the prevailing southwesterly flow that is modified by the storm-induced westerlies immediately behind the convective line.

From the numerical experiment with synoptic-scale forcing but without the island topography over Taiwan, a large-scale cloud band is simulated within the Taiwan Strait without the localized rainfall maximum along the northwestern coast. The coastal rainfall maximum is simulated when the influences of the orographic effects are included. The results from the radar analyses and numerical simulations indicate that the convergence off the northwestern coast is a combination of the synoptic-scale forcing, orographic effects, and the feedback of the convection. The offshore convergence is important for the production of the rainfall maximum along the northwestern coast of Taiwan.

Current affiliation: School of General Education, Aletheia University, Tamshui, Taipei, Taiwan

Corresponding author address: Dr. Yi-Leng Chen, Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822. Email: dave@soest.hawaii.edu

Abstract

The role of offshore convergence on the coastal rainfall maximum along the northwestern coast of Taiwan is analyzed based on TAMEX (Taiwan Area Mesoscale Experiment) data and numerical experiments using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5).

From a case study during TAMEX IOP 3, moderate rainfalls (∼40 mm h–1) are observed along the northwestern coast of Taiwan associated with the arrival of three rainbands in succession during 1000–1600 LST. These rainbands form over the Taiwan Strait with northeast–southwest or north–south orientation. They intensify off the northwestern coast. There is a tendency for the most intense echoes to align in a northeast–southwest orientation off the northwestern coast. An orographically enhanced convergence zone with a northeast–southwest orientation occurs in the area where the deflected southerly flow converges with the prevailing southwesterly flow that is modified by the storm-induced westerlies immediately behind the convective line.

From the numerical experiment with synoptic-scale forcing but without the island topography over Taiwan, a large-scale cloud band is simulated within the Taiwan Strait without the localized rainfall maximum along the northwestern coast. The coastal rainfall maximum is simulated when the influences of the orographic effects are included. The results from the radar analyses and numerical simulations indicate that the convergence off the northwestern coast is a combination of the synoptic-scale forcing, orographic effects, and the feedback of the convection. The offshore convergence is important for the production of the rainfall maximum along the northwestern coast of Taiwan.

Current affiliation: School of General Education, Aletheia University, Tamshui, Taipei, Taiwan

Corresponding author address: Dr. Yi-Leng Chen, Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822. Email: dave@soest.hawaii.edu

Save
  • Akaeda, K., J. Reisner, and D. Parsons, 1995: The role of mesoscale and topographically induced circulations initiating a flash flood observed during the TAMEX project. Mon. Wea. Rev., 123 , 17201739.

    • Search Google Scholar
    • Export Citation
  • Arakawa, A., 1972: Design of the UCLA general circulation model. Numerical simulation of weather and climate. Tech. Rep. 7, Department of Meteorology, University of California, Los Angeles, CA, 116 pp.

    • Search Google Scholar
    • Export Citation
  • Atlas, D., R. C. Srivastava, and R. S. Sekhon, 1973: Doppler radar characteristics of precipitation at vertical incidence. Rev. Geophys. Space Phys., 11 , 135.

    • Search Google Scholar
    • Export Citation
  • Banta, R. M., 1990: The role of mountain flows in making clouds. Atmospheric Processes over Complex Terrain, Meteor. Monogr., No. 45, Amer. Meteor. Soc., 229–284.

    • Search Google Scholar
    • Export Citation
  • Blackadar, A. K., 1979: High resolution models of the planetary boundary layer. Advances in Environmental Science and Engineering, Vol. 1, J. R. Pfafflin and E. N. Ziegler, Eds., Gordon and Breach Science, 50–85.

    • Search Google Scholar
    • Export Citation
  • Blumen, W., Ed.,. . 1990: Atmospheric Processes over Complex Terrain. Meteor. Monogr., No. 45, Amer. Meteor. Soc., 323 pp.

  • Bougeault, P., 1983: A non-reflective upper boundary condition for limited-height hydrostatic models. Mon. Wea. Rev., 111 , 420429.

  • Braun, S. A., and R. A. Houze Jr.,, 1994: The transition zone and secondary maximum of radar reflectivity behind a midlatitude squall line: Results retrieved from Doppler radar data. J. Atmos. Sci., 51 , 27332751.

    • Search Google Scholar
    • Export Citation
  • Byers, H. R., and R. R. Braham Jr.,, 1949: The Thunderstorm. Superintendent of Documents, Government Printing Office, Washington DC, 287 pp.

    • Search Google Scholar
    • Export Citation
  • Chen, C-S., W-S. Chen, and Z-S. Deng, 1991: A study of a mountain-generated precipitation system in northern Taiwan during TAMEX IOP 8. Mon. Wea. Rev., 119 , 25742606.

    • Search Google Scholar
    • Export Citation
  • Chen, G. T-J., and C-C. Yu, 1988: Study of low-level jet and extremely heavy rainfall over northern Taiwan in the Mei-Yu season. Mon. Wea. Rev., 116 , 884891.

    • Search Google Scholar
    • Export Citation
  • Chen, S-J., Y-H. Kuo, W. Wang, Z-Y. Tao, and B. Cui, 1998: A modeling case study of heavy rainstorms along the Mei-yu front. Mon. Wea. Rev., 126 , 23302351.

    • Search Google Scholar
    • Export Citation
  • Chen, Y-L., and N. B-F. Hui, 1990: Analysis of a shallow front during the Taiwan area mesoscale experiment. Mon. Wea. Rev., 118 , 26492667.

    • Search Google Scholar
    • Export Citation
  • Chen, Y-L., . 1992: Analysis of a relative dry front during the Taiwan area mesoscale experiment. Mon. Wea. Rev., 120 , 24422468.

  • Chen, Y-L., and A. J. Nash, 1994: Diurnal variation of surface airflow and rainfall frequencies on the island of Hawaii. Mon. Wea. Rev., 122 , 3456.

    • Search Google Scholar
    • Export Citation
  • Chen, Y-L., and J. Li, 1995a: Characteristic of surface airflow and pressure patterns over the island of Taiwan during TAMEX. Mon. Wea. Rev., 123 , 695716.

    • Search Google Scholar
    • Export Citation
  • Chen, Y-L., and J. Li, 1995b: Large-scale conditions favorable for the development of heavy rainfall during TAMEX IOP 3. Mon. Wea. Rev., 123 , 29783002.

    • Search Google Scholar
    • Export Citation
  • Chen, Y-L., and J. Feng, 2001: Numerical simulations of airflow and cloud distributions over the windward side of the island of Hawaii. Part I: The effects of trade-wind inversion. Mon. Wea. Rev., 129 , 11171134.

    • Search Google Scholar
    • Export Citation
  • Chen, Y-L., Y-X. Zhang, and N. B-F. Hui, 1989: Analysis of a surface front during the early summer rainy season over Taiwan. Mon. Wea. Rev., 117 , 909931.

    • Search Google Scholar
    • Export Citation
  • Doviak, R. J., P. S. Ray, R. G. Strauch, and L. J. Miller, 1976: Error estimation in wind fields derived from dual-Doppler radar measurements. J. Appl. Meteor., 15 , 868878.

    • Search Google Scholar
    • Export Citation
  • Drazin, P. G., 1961: On the steady flow of fluid of variable density past an obstacle. Tellus, 13 , 239251.

  • Dudhia, J., 1989: Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model. J. Atmos. Sci., 46 , 30773107.

    • Search Google Scholar
    • Export Citation
  • Dudhia, J., . 1993: A nonhydrostatic version of the Penn State–NCAR Mesoscale Model: Validation tests and simulation of an Atlantic cyclone and cold front. Mon. Wea. Rev., 121 , 14931513.

    • Search Google Scholar
    • Export Citation
  • Garrett, A. J., 1980: Orographic cloud over the eastern slopes of Mauna Loa Volcano, Hawaii, related to insolation and wind. Mon. Wea. Rev., 108 , 931941.

    • Search Google Scholar
    • Export Citation
  • Giambelluca, T. W., M. A. Nullet, and T. A. Schroeder, 1986: Rainfall atlas of Hawaii. Rep. R76, Hawaii Department of Land and Natural Resources, Honolulu, HI, 267 pp.

    • Search Google Scholar
    • Export Citation
  • Grell, G. A., 1993: Prognostic evaluation of assumptions used by cumulus parameterization. Mon. Wea. Rev., 121 , 764787.

  • Grell, G. A., J. Dudhia, and D. R. Stauffer, 1994: A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5). NCAR Tech. Note NCAR/TN-397+IA, 113 pp.

    • Search Google Scholar
    • Export Citation
  • Houze Jr.,, R. A., S. A. Rutledge, M. I. Biggerstaff, and B. F. Smull, 1989: Interpretation of Doppler weather radar displays of midlatitude mesoscale convective systems. Bull. Amer. Meteor. Soc., 70 , 608619.

    • Search Google Scholar
    • Export Citation
  • Kain, J. S., and J. M. Fritsch, 1993: Convective parameterization for mesoscale models: The Kain–Fritsch scheme. Representation of Cumulus Convection in Numerical Models, Meteor. Monogr., No. 46, Amer. Meteor. Soc., 165–170.

    • Search Google Scholar
    • Export Citation
  • Klemp, J. B., and D. R. Durran, 1983: An upper boundary condition permitting internal gravity wave radiation in numerical mesoscale models. Mon. Wea. Rev., 111 , 430444.

    • Search Google Scholar
    • Export Citation
  • Kuo, Y-H., and G. T-J. Chen, 1990: The Taiwan Area Mesoscale Experiments: An overview. Bull. Amer. Meteor. Soc., 71 , 488503.

  • Leary, C. A., and R. A. Houze Jr.,, 1979: The structure and evolution of convection in a tropical cloud cluster. J. Atmos. Sci., 36 , 437457.

    • Search Google Scholar
    • Export Citation
  • Lee, W-C., R. E. Carbone, and R. M. Wakimoto, 1992: The evolution and structure of a “bow-echo–microburst” event. Part I: The Microburst. Mon. Wea. Rev., 120 , 21882210.

    • Search Google Scholar
    • Export Citation
  • Leopold, L. B., 1949: The interaction of trade wind and sea breeze, Hawaii. J. Meteor., 6 , 312320.

  • Li, J., and Y-L. Chen, 1998: Barrier jets during TAMEX. Mon. Wea. Rev., 126 , 959971.

  • Li, J., and W-C. Lee, 1997: Analysis of a heavy rainfall event during TAMEX. Mon. Wea. Rev., 125 , 10601081.

  • Mohr, C. G., L. J. Miller, and H. W. Frank, 1986: The merger of mesoscale datasets into a common Cartesian format for efficient and systematic analysis. J. Atmos. Oceanic Technol., 3 , 144161.

    • Search Google Scholar
    • Export Citation
  • O'Brien, J. J., 1970: Alternative solutions to the classical vertical velocity problem. J. Appl. Meteor., 9 , 197203.

  • Overland, J. E., and N. A. Bond, 1993: The influence of coastal orography: The Yakutat storm. Mon. Wea. Rev., 121 , 13881397.

  • Overland, J. E., . 1995: Observations and scale analysis of coastal wind jets. Mon. Wea. Rev., 123 , 29342941.

  • Oye, R., and R. E. Carbone, 1981: Interactive Doppler editing software. Preprints, 20th Conf. on Radar Meteorology, Boston, MA, Amer. Meteor. Soc., 683–689.

    • Search Google Scholar
    • Export Citation
  • Parsons, D. B., and S. B. Trier, 1990: Taiwan Area Mesoscale Experiment: Doppler radar operations summary. NCAR Tech. Note NCAR/TN-315+STR, 59 pp. [Available from Information Services Office, NCAR, P.O. Box 3000, Boulder, CO 80307.].

    • Search Google Scholar
    • Export Citation
  • Rasmussen, R. M., P. R. Smolarkiewicz, and J. Warner, 1989: On the dynamics of Hawaiian cloud bands: Comparison of model results with observations and island climatology. J. Atmos. Sci., 46 , 15891608.

    • Search Google Scholar
    • Export Citation
  • Rotunno, R., J. B. Klemp, and M. L. Weisman, 1988: A theory for strong, long-lived squall line. J. Atmos. Sci., 45 , 463485.

  • Smith, R. B., 1979: The influence of mountains on the atmosphere. Advances in Geophysics, Vol. 21, Academic Press, 87–230.

  • Smith, R. B., . 1982: Synoptic observations and theory of orographically disturbed wind and pressure. J. Atmos. Sci., 39 , 348364.

  • Smolarkiewicz, P. R., R. M. Rasmussen, and T. L. Clark, 1988: On the dynamics of Hawaiian cloud bands: Island forcing. J. Atmos. Sci., 45 , 18721905.

    • Search Google Scholar
    • Export Citation
  • Smull, B. F., and R. A. Houze Jr.,, 1987: Dual-Doppler radar analysis of a mid-latitude squall line with a trailing region of stratiform rain. J. Atmos. Sci., 44 , 21282148.

    • Search Google Scholar
    • Export Citation
  • Stephens, G. L., 1984: The parameterization of radiation for numerical weather prediction and cloud models. Mon. Wea. Rev., 112 , 826867.

    • Search Google Scholar
    • Export Citation
  • Sun, W-Y., C. C. Wu, and W. R. Hsu, 1991: Numerical simulation of mesoscale circulation in Taiwan and surrounding area. Mon. Wea. Rev., 119 , 25582573.

    • Search Google Scholar
    • Export Citation
  • Tao, S., and L. Chen, 1987: A review of recent research on the east Asia summer monsoon in China. Monsoon Meteorology, C.-P. Chang and T. N. Krishnamurti, Eds., Oxford University Press, 60–92.

    • Search Google Scholar
    • Export Citation
  • Trier, S. B., D. B. Parsons, and T. J. Matejka, 1990: Observations of a subtropical cold front in a region of complex terrain. Mon. Wea. Rev., 118 , 24492470.

    • Search Google Scholar
    • Export Citation
  • Wang, S-T., 1986: Observational analysis of the interaction between fronts and the orography in Taiwan during the late winter monsoon season. Proc. Int. Conf. on Monsoon and Mesoscale Meteorology, Taipei, Taiwan, The Meteorological Society of the Republic of China, 123–135.

    • Search Google Scholar
    • Export Citation
  • Wilson, J. W., R. D. Roberts, C. Kessinger, and J. McCarthy, 1984: Microburst wind structure and evolution of Doppler radar for airport wind shear detection. J. Climate Appl. Meteor., 23 , 898915.

    • Search Google Scholar
    • Export Citation
  • Yeh, H-C., and Y-L. Chen, 1998: Characteristics of rainfall distribution over Taiwan during TAMEX. J. Appl. Meteor., 37 , 14571469.

  • Zhang, D., and R. A. Anthes, 1982: A high-resolution model of the planetary boundary layer—Sensitivity tests and comparisons with SESAME-79 data. J. Appl. Meteor., 21 , 15941609.

    • Search Google Scholar
    • Export Citation
  • Zipser, E. J., 1977: Mesoscale and convective-scale downdrafts as distinct components of squall-line circulation. Mon. Wea. Rev., 105 , 15681589.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 315 129 10
PDF Downloads 158 35 3