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Tropical Night (Nocturnal Thermal High) in the Mountainous Coastal City

  • Choi, Hyo (Dept of Atmospheric Environmental Sciences, Kangnung National University)
  • Published : 2004.11.01

Abstract

The investigation of driving mechanism for the formation of tropical night in the coastal region, defined as persistent high air temperature over than 25$^{\circ}C$ at night was carried out from August 14 through 15, 1995. Convective boundary layer (CBL) of a 1 km depth with big turbulent vertical diffusion coefficients is developed over the ground surface of the inland basin in the west of the mountain and near the top of the mountain, while a depth of thermal internal boundary layer (TIBL) like CBL shrunken by relatively cool sea breeze starting at 100 km off the eastern sea is less than 150 m from the coast along the eastern slope of the mountain. The TIBL extends up to the height of 1500 m parallel to upslope wind combined with valley wind and easterly sea breeze from the sea. As sensible heat flux convergences between the surface and lower atmosphere both at the top of mountain and the inland coast are much greater than on the coastal sea, sensible heat flux should be accumulated inside both the TIBL and the CBL near the mountain top and then, accumulated sensible heat flux under the influence of sea breeze circulation combined with easterly sea breeze from sea to inland and uplifted valley wind from inland to the mountain top returning down toward the eastern coastal sea surface should be transported into the coast, resulting in high air temperatures near the coastal inland. Under nighttime cooling of ground surface after sunset, mountain wind causes the daytime existed westerly wind to be an intensified westerly downslope wind and land breeze further induces it to be strong offshore wind. No sensible heat flux divergence or very small flux divergence occurs in the coast, but the flux divergences are much greater on the top of the mountain and along its eastern slope than on the coastal inland and sea surfaces. Thus, less cooling down of the coastal surface than the mountain surface and sensible heat transfer from warm pool over the coast into the coastal surface produce nocturnal high air temperature on the coastal inland surfaces, which is not much changed from daytime ones, resulting in the persistence of tropical night (nocturnal thermal high) until the early in the morning.

Keywords

Tropical night;Nocturnal thermal high;Convective boundary layer;Thermal internal boundary layer;Sensible heat flux;Valley wind;Sea breeze;Mountain wind;Land breeze;Warm pool

References

  1. Raynor, G. S., S. SethuRaman and R. M. Brown, 1979, Formation and characteristics of coastal internal boundary layer during onshore flows, Boundary Layer Meteor., 16, 4587-514
  2. Pielke, R. A., 1984, Mesoscale meteorological modeling, Academic Press, 612pp
  3. Whiteman, C. D., 1990, Observations of thermally developed wind system in mountainous terrain, Atmospheric Processes over complex terrain, Meteor. Monogr., Amer. Meteor. Soc., 40, 5-42
  4. Kuwagata, T., M. Sumioka, N. Masuko and J. Kondo, 1990, The daytime PBL heating process over complex terrain in central Japan and fair and calm wether conditions, Part 1: Meso-scale circulation and the PBL heating rate, J. Meteor. Soc, Japan, 68, 625-638
  5. Choi, H. and J. Kim, 1997, Three-dimensional numerical prediction on the evolution of nocturnal thermal high (tropical night) in a basin, Korean J. Geophy. Res., 25(1), 57-81
  6. Choi, H. and J. Kim, 1997, Three-dimensional numerical prediction on the evolution of nocturnal thermal high (tropical night) in a basin, Korean J. Geophy. Res., 25(1), 57-81
  7. Choi, H., 2003, Increase of ozone concentration in an inland basin during the period of nocturnal thermal high, Water, Air & Soil Poll: Focuss, 3, 31-52
  8. Choi, H., 2004, Persistent high concentration of ozone during windstorm conditions in southern Korea, Meteor. & Atmos. Phys., 87, 93-107
  9. Choi, H., Y. H. Zhang and S. Takahashi, 2004, Recycling of suspended particulates by the interaction of sea-land breeze circulation and complex coastal terrain, Meteor. & Atmos. Phys., 87, 109-120
  10. Takahashi, S., 1997, Manual of LAS model revised by Dr. J. Sato, Meteorological Research Institute of Japan, 50pp
  11. KlemP, J. B. and D. R. Durran, 1983, An upper condition permitting internal gravity wave radiation in numerical mesoscale models, Mon. Wea. Rev., 111, 430-440 https://doi.org/10.1175/1520-0493(1983)111<0430:AUBCPI>2.0.CO;2
  12. Orlanski, I., 1976, A simple boundary condition for unbounded hyperbolic flows, J. Comp. Phys., 21. 251-269 https://doi.org/10.1016/0021-9991(76)90023-1
  13. Yamada, T., 1983, Simulation of nocturnal drainage flows by a q2-1 turbulence closure model, J. Atmos. Sci., 40, 91-106 https://doi.org/10.1175/1520-0469(1983)040<0091:SONDFB>2.0.CO;2
  14. Yamada, T. and G. L. Mellor, 1983, A numerical simulation of the BOMEX data using a turbulence closure model coupled with ensemble cloud relations, Q. J. R. Meteor. Soc., 105, 95-944
  15. Katayama, A. 1972, A simplified scheme for computing radiative transfer in the troposphere, Technical report No. 6, Dept. of Meteor., U.C. L.A., 77pp
  16. Businger, J. A., 1973, Turbulence transfer in the atmospheric surface layer, In Workshop on micrometeorology (D. A. Haugen, ed), Amer. Meteor. Soc., 67-100pp
  17. Monin, A. S., 1970, The atmospheric boundary layer., Annual Review of Fluid Mechanics, 2, 225-250 https://doi.org/10.1146/annurev.fl.02.010170.001301
  18. Deardoff, J. W., 1978, Efficient prediction of ground surface temperature and moisture with inclusion of a layer of vegetation, Geophys. Res., 38, 659-661
  19. KMA, 1995, Observed data made by Kangnung Meteorological Administration