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基于2012年4月15日至23日在长江口北槽中段获得的枯季水文泥沙定点观测资料,运用通量机制分解法探讨了测点处从小潮到大潮连续16个潮周期的输盐输沙特征。结果表明,从小潮到大潮,测点处向海输盐中,欧拉余流输移项贡献最大;向陆输盐中,小潮时以“潮泵效应”输移项为主,中潮和大潮以斯托克斯漂移输移项为主,垂向净环流输移项次之。在向海输沙中,欧拉余流输移项贡献最大;在向陆输沙中,以斯托克斯漂移输移项为主,垂向净环流输移项次之。由于盐水楔的出现,北槽存在重力环流,这对北槽泥沙输运过程具有重要影响。小潮时水体垂向混合弱于大潮,盐水楔主要出现在近底部水层,这是导致垂向净环流输沙项对向陆输沙的贡献率从小潮向大潮不断减小的一个重要原因。
Based on the observed data of dry-season hydrologic sediment obtained in the middle section of the north channel of the Yangtze River estuary from April 15 to April 23, 2012, the mechanism of flux mechanism decomposition was used to investigate the salt transport from small tide to tidal continuous 16 tide cycles Sediment transport characteristics. The results show that from the tide to the tide, the contribution of the Euclidean residual current is the largest in the salt transport to the sea at the measuring point. In the salt transport to the land, the “tidal pump effect” And the tide to Stokes drift transfer-based, vertical net circulation transfer followed. In the process of sediment transport to the sea, the Eurasian residual current has made the largest contribution to the transport. In the case of inland silt transport, the Stokes drift and transference are the main items, followed by the vertical net circulation. Due to the occurrence of salt wedges, there is a gravity circulation in the north trough, which has an important influence on sediment transport in the north trough. The vertical mixing of water body is weaker than the tide during the tide, and the wedge of salt water mainly appears in the bottom bottom water layer. This is an important reason that the contribution rate of vertical net circulation to the onshore transportation decreases from small tide to tidal tide.