Unusually High Mean Sea Level in September 1971 Along the South Coast of Japan

A few typical cases of unusual high or low mean sea level are selected from the tidal data for Tokyo Bay by the following ways: (1) Unusual days are selected at each station under the condition that the magnitude of daily mean tidal residual be more than twice its standard deviation. (2) We take up those cases in which more than three consecutive unusual days occur simultaneously in the whole area of Tokyo Bay. Both meteorological and oceanographic factors are considered in connection with the occurrence of unusual high or low sea level, which takes place once a year or so. At such times the weather condition is rather gentle in general, and the oceanic condition seems to be responsible for the unusual rise or fall. Warmer sea surface temperature is likely to be associated with the rising of the sea level and colder temperature with the falling. In the inner part of the bay, the land and sea breezes are related to these variations, so that the former (southerly wind) I serves to raise up warmer water, and the latter (northerly wind) to drive out colder water.