夏季珠江口溶解氧垂向输运数值模拟研究

Numerical study on the vertical transport of dissolved oxygen in the Zhujiang (Pearl) River Estuary in summer

通过建立一个珠江口三维水质模型,对夏季珠江口溶解氧垂向输运进行研究。结果表明:潮汐、风及上升流间歇性破坏层化,令溶解氧垂向对流及扩散通量的方向和大小随潮汐发生周期性变化。在西四口门海域,由于水体层化稳定,垂向上对流及扩散作用产生的溶解氧输运通量都较小,且相互平衡;在伶仃洋内的深槽,径流与潮汐的相互作用强烈,层化被间歇性地打破,溶解氧的垂向对流通量大于扩散通量,导致底层溶解氧浓度产生波动;在伶仃洋内的西部浅滩上,层化相对稳定,溶解氧的垂向扩散通量大于对流通量。这表明在珠江口不同区域,垂向的对流扩散作用对溶解氧垂向输运起不同作用,从而影响表底层溶解氧的浓度。

A three dimensional water quality model was developed to investigate DO vertical transport in the Zhujiang（Pearl） River Estuary（PRE） in summer.Results show that the tidal,wind,topography and upwelling breakdown pycnocline in the PRE intermittently,leading to the fluctuation of DO vertical advective and dispersive fluxes associate with tidal cycle.Outside the west outlets,DO vertical advective and dispersive fluxes are low due to the stable stratification.In the deep channel,interaction between fresh water discharge and tidal force is intensified,leading to intermittent breakdown of stratification.DO vertical advective fluxes are greater than dispersive fluxes.In the western shoal of the Lingdingyang Estuary,stratification is more stable than in deep channel area,and the DO vertical advective fluxes is lower than dispersive fluxes.These results indicate that impacts of advection and dispersion on DO vertical transport show spatial differences in the PRE,and influence the DO concentration in the water column.