中国沿岸海域月平均潮差变化规律

SEASONAL CHANGES OF THE MEAN TIDAL RANGE ALONG THE CHINESE COASTS

本文根据中国沿岸月平均潮差(MMTR)分布变化的特点,把它区分为单峰及双峰两种主要的不同类型,并从天文因素及地理条件角度分析其成因,特别对河口水域由于径流、地形作用而产生的潮波变形及由此而引起的潮差变化作了较详细的论述,得出有实用意义的结论。

This paper describes the characteristics of the monthly-mean tidal range (MMTR) along the Chinese coasts. The seasonal variation of tidal ranges can be divided into two types: double-peaked and single-peaked. The former is situated in the coastal regions and the latter is located in the estuarine regions. In the coastal regions, the variation of MMTR is closely related with the tidal properties of the local areas. Generally, in diurnal tidal waters, the maximum MMTR occurs in June and December, the minimum takes place in March and September; in semidiurnal tidal waters, the maximum occurs in March and September, and the minimum takes place in June and December.The runoff and topography are the main factors affecting the variation of MMTR in estuarine regions. Commonly, in nearly estuarine reach the tidal range is small during the flood seasons and large during the dry seasons; On the contrary, the tidal range in the estuarine reach is large during the flood seasons and small during the dry seasons. During the flood seasons, the mean water level was raised due to flood water, thus enabling the flood wave from the upstream to interact with the tidal wave from the downstream in the estuarine reach and deforming the tidal wave severely. So the features of the tidal wave are changed, among which the phase of the tidal current and tidal level increased greatly as compared with that during the dry seasons, and the tidal wave becomes more or less like a standing wave. This results in the increasing of the tidal ranges. In the offshore areas, the seasonal variation of the tidal range is related with the tidal properties which are controlled by the tidal wave from the sea.