摘要
本文从理论上研究了局地风场对夏季长江冲淡水路径变化的效应,主要结果如下:(1)对于长江冲淡水路径变化来说,夏季本区平均风场的效应与底形效应相比可以忽略。(2)当平均风涡度场的效应与底形效应相当时,所得的近似解表明,底形效应将使长江冲淡水的路径向左转向,而局地风场效应只对该路径作微小的订正。
Historical data show that the general distribution of residual currents and the axis of salt tongue in the summertime Changjiang Diluted Water (CDW) is shifted to the northeast, which is to say, the main body of the CDW moves towards the northeast, instead of the southeast. In the first part of this paper, the behavior of the path of CDW is explained by means of properties of certain topographic waves in shallow sea with vaiable depth. The path equation used in part I, however, does'nt involve the effect of local wind. The corresponding path equation with the wind effect is established and analyzed here in order to see the effect of local wind on the CDW path. (1) In comparison with the effect of topography, the effect of the wind vorticity averaged over the CDW area (WVA) on the path of CDW can be neglected, which bears out again that the effect of topography is the main factor responsible for the diversion of the main body of CDW, as pointed out in part 1. (2) Under certain synoptic situations, the order of magnitude of WVA can be comparable to thu of the topography effect, thus, an approximate solution for the path equation involving both topography effect and wind vorticity terms shows that the effect of topography will drive the path of CDW to diverse left and the local wind will modify somewhat. (3) In the case of constant depth, if the WVA is five times as much as the magnitude of averaged wind vorticity all over the world ocean area, the path will be chaotic, which may imply that the CDW has mixed up with its surrounding water and become eddies.
出处
《海洋与湖沼》
CAS
CSCD
北大核心
1989年第2期139-148,共10页
Oceanologia Et Limnologia Sinica
