Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
On the Upheaving Effect of Stationary and Non-stationary Winds upon Sea Level (Continued) An Investigation on Meteorological Tides in the Neighboring Seas of Japan-3rd Paper
S. Unoki
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1951 Volume 29 Issue 10 Pages 336-346

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Abstract

Assuming a simple harmonic variation of wind, the author discussd the phase-relation between non-stationary wind and the corresponding elevation of sea level, the effects of variation of wind direction and Coriolis'force on sea level, which had scarcely been investigated, by using the concept of mass transport as well as the results of his preceding paper. Moreover, he showed a method to obtain the elevation by Fourier's integral, in case of arbitrary change of wind velocity and direction with respect to place and time.
Even when wind direction varies, the phase-difference is not generally recognized. But on the other hand, when the wind velocity varies, its direction being constant, the phase-difference is closely connected with the latidude of the place, the angle between the wind direction and coastal line, and the rate of variation of wind velocity. It seems to him that the effect of Coriolis' force on the upheaval of water surface caused by wind is unexpectedly large. For example, on account of Coriolis'force, the elevation at the shore caused by wind, whose velocity changes very slowly, is larger when the wind blows parallel to the coastal line than when it blows perpendicular to it. Moreover, the phase-difference vanishes as long as Coriolis'force is neglected.
It is also concluded that the elevation of surface is considerably larger when the wind direction rotates clockwise than when it rotates counter-clockwise, even when the absolute value of wind velocity and the rate of variation of wind direction are equal for the two cases. Accordingly, a larger elevation occurs when a cyclone passes towards north through the west side of a bay than when it passes the east side of it.
As an cxample, where atmospheric surface pressure and wind act simultaneously on water surface, the elevation caused by the surface pressure and the corresponding wind according to Brunt-Douglas' formula were obtained, by considering that, when the field of one of these two factors is given, the other field will be decided naturally.

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