Abstract
General features of storm surge caused on the coasts of the Kanto and Tokai districts are investigated by use of hourly reading s of tidal records for the ten years from 1953 to 1962. Storm surges on these coasts are mainly caused by two mechanisms: one is the sea level rise in response to atmospheric pressure fall, and the other is the so-called ‘wind set-up’. In the previous paper (Isozmu,1969), it was shown statistically that there exist sea level variations travelling from east to west along the Pacific coast of West Japan in the variation of daily mean sea level. But they are not seen to accompany the storm surges analyzed here.
In the heads of Ise Bay and Tokyo Bay which are shallow in depth, the effect of ‘wind set-up’ superposed on sea level rise caused by atmospheric pressure fall is remarkable, and sometimes extraordinary destructive surges develop there.
On the coasts facing Surug a Bay, Sagami Bay or the open ocean the rise of sea level caused by wind set-up is relatively small comp ared with that due to atmospheric pressure fall because there are only narrow strip of shallow waters between these coasts and the deep ocean.
In addition, the surge height is affected also by wind waves and swell, i.e. the so-called ‘wave set-up’. This effect is most predominant in the storm surge at Maisaka. For example, in the storm surge that accompanied the Typhoon ‘Wilda’, Sept.25,1964, the sea levelrise contributed by the effect of wave set-up was about twice as large as the rise due to atmospheric pressure fall.
Storm surges at Okada Harbor, Oshima Island are mainly caused by deep atmospheric pressure fail accompanying the pas sage of a typhoon and the effect of wind set-up is of course rather weak. These surges also contain interesting sea level changes which are represented qualitatively by KAJIURA (1956), who maintained that there exist sea level changes related to the distribution of wind stress curl in the area of a typhoon moving with a circular wind system.
