A Laboratory Experiment on the Dynamics of the Land and Sea Breeze

Shigeki Mitsumoto National Institute for Environmental Studies, Tsukuba, Ibaraki 305, Japan

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Hiromasa Ueda National Institute for Environmental Studies, Tsukuba, Ibaraki 305, Japan

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Hiroyuki Ozoe School of Engineering, Okayama University, Okayama 700. Japan

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Abstract

The land and sea breeze (LSB) circulation was simulated in a laboratory using a temperature controlled water tank. Flow visualization by tellurium and phenolphthalein and velocity measurement by laser-Doppler velocimeter were carried out in addition to temperature measurements. from similarity considerations, the simulated flow pattern was shown to have good correspondence with that in the atmosphere. It was shown that the overall features of the LSB flow pattern consist of a closed circulating motion caused by the periodically changing horizontal temperature difference between the land and the sea, and several kinds of small-scale motions induced by the periodic variation of the land surface temperature itself. The most important small-scale motion is the cellular convection which occurs all over the land surface due to unsteady heating from below in the morning calm. Other small-scale motions such as longitudinal vortex rows which are formed inland throughout the sea breeze layer, and gravity currents, were also investigated and shown to contribute significantly to the dynamics of the LSB and the transport of a pollutant within it.

Abstract

The land and sea breeze (LSB) circulation was simulated in a laboratory using a temperature controlled water tank. Flow visualization by tellurium and phenolphthalein and velocity measurement by laser-Doppler velocimeter were carried out in addition to temperature measurements. from similarity considerations, the simulated flow pattern was shown to have good correspondence with that in the atmosphere. It was shown that the overall features of the LSB flow pattern consist of a closed circulating motion caused by the periodically changing horizontal temperature difference between the land and the sea, and several kinds of small-scale motions induced by the periodic variation of the land surface temperature itself. The most important small-scale motion is the cellular convection which occurs all over the land surface due to unsteady heating from below in the morning calm. Other small-scale motions such as longitudinal vortex rows which are formed inland throughout the sea breeze layer, and gravity currents, were also investigated and shown to contribute significantly to the dynamics of the LSB and the transport of a pollutant within it.

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