基于HYCOM的风生大洋环流模拟及季节变化分析

基于垂向混合坐标系统的海洋模式HYCOM建立了全球大洋气候态环流场.在此基础上与前人研究工作进行对比,分析和讨论了全球风生大洋环流场的季节变化情况.从模拟结果看该模式具有较好的模拟能力,可以合理地模拟南极绕极流、赤道流系、黑潮和湾流等世界各主要大洋流系.从断面温度场、流函数分布和断面流量场等分析显示:南极绕极流堪称世界最强流,湾流整体强于黑潮,3者都具有夏季增强、冬季减弱的特点.HYCOM模式在国外的研究方兴未艾,而在国内的应用尚处在起步阶段.本文通过对该模式的介绍和结果分析,向读者推荐使用该模式.     

胶州湾及其邻近海域潮流和污染物扩散的数值模拟

采用曲线网格技术，将ECOMSED模式应用于胶州湾的潮流和污染物COD的稀释扩散研究，建主了一个三维保守污染物COD输运的对流扩散数值模型，对胶州湾M2分潮和COD污染状况进行了模拟。结果表明，胶州湾及其附近海域存在许多大小、强弱和旋转方向不同的余流涡；湾内COD浓度东部比西部高，湾口外的COD浓度等值线成舌状分布，向东伸展；余流和COD浓度垂向分布差异并不显。模拟结果与胶州湾的实测资料符合较好。     

Seasonal variation of the barrier layer in the PN section

In this paper, we use the conductivity-temperature-depth (CTD) observation data and a three-dimensional ocean model in a seasonally-varying forcing field to study the barrier layer (BL) in the PN section in the East China Sea (ECS). The BL can be found along the PN section with obviously seasonal variability. In winter, spring and autumn, the BL occurs around the slope where the cold shelf water meets with the warm Kuroshio water. In summer, the BL can also be found in the shelf area near salinity front of the Changjiang (Yangtze) River Dilution Water (YRDW). Seasonal variations of BL in the PN section are caused by local hydrological characteristics and seasonal variations of atmospheric forcing. Strong vertical convection caused by sea surface cooling thickens the BL in winter and spring in the slope area. Due to the large discharge of Changjiang River in summer, the BL occurs extensively in the shelf region where the fresh YRDW and the salty bottom water meet and form a strong halocline above the seasonal thermocline. The formation mechanism of BL in the PN section can be explained by the vertical shear of different water masses, which is called the advection mechanism. The interannual variation of BL in summer is greatly affected by the YRDW. In the larger YRDW year (such as 1998), a shallow but much thicker BL existed on the shelf area. Supported by National Basic Research Program of China (973 Program, No. 2005CB422303 and 2007CB411804), the Key Project of the International Science and Technology Cooperation Program of China (No. 2006DFB21250), the “111 Project” of the Ministry of Education (No. B07036), the Program for New Century Excellent Talents in University, China (No. NECT-07-0781)     

The observed currents in summer in the Bohai Sea

A harmonic method was used to analyze the tidal currents observed in summer at 11 stations made from 1996 to 2001 in the Bohai Sea, China. Data was compared among different instruments and intervals. Elliptic elements were calculated based on harmonic constants, of which vertical distributions of the maximum speed and rotation direction were discussed for understanding the characteristics of diurnal and semi-diurnal tidal current components. The results indicate that the maximum speed of M2 tidal current component is much larger than that of K1; the rotation direction of M2 tidal current constituent is clockwise in the central part of the Bohai Sea and in the Laizhou Bay, but anticlockwise in the Liaodong Bay and Bohai Bay. For K1 tidal current constituent, it is clockwise in the central Bohai Sea but anti-clockwise in the Laizhou Bay and Liaodong Bay. The tidal currents in most stations in the Bohai Sea were regular semidiurnal except for those in the central Bohai Sea, being irregular semidiurnal.