三种垂向混合方案对HYCOM模拟北太平洋西边界流系的影响研究

Effects of three vertical mixing schemes on HYCOM simulations of the north Pacific western boundary current system

基于HYCOM(Hybrid Coordinate Oceanic Circulation Model),以OFES(OGCM for the Earth Simulator)资料为参考,分析了KPP、MY2.5、KT三种不同混合方案对北太平洋西边界流系的模拟结果的影响。结果表明:三种不同混合方案模拟的上层海洋平均流场与OFES资料相似,但在流向和流幅上略有差异,其中KPP方案模拟的流速与OFES资料最为接近,MY2.5方案次之,KT方案与其差别最大。通过代表性断面上流速的对比分析,对模式就北赤道流、棉兰老流、棉兰老潜流、黑潮的模拟效果进行比较,KPP方案模拟的效果同前人的观测和研究最为接近。分析了北赤道流,棉兰老流,棉兰老潜流,黑潮的流量的季节变化特征,其中KPP方案与OFES资料计算的棉兰老流和棉兰老潜流的季节变化特征与前人描述比较一致,表现为春强秋弱。KPP方案和OFES资料的计算结果表明,北赤道流和棉兰老流大致上是同向变化的,而在冬季棉兰老流同黑潮的变化基本上是一致的。

Based on the OGCM for the Earth Simulator （OFES） and simulations of the north Pacific western boundary current system via HYCOM （Hybrid Coordinate Oceanic Circulation Model）, a comparison is conducted of the performances of three different kinds of vertical mixing schemes： the K-Profile Parameterization （KPP） scheme, the Kraus and Turner （KT） scheme, and the Mellor-Yamada level 2.5 （MY2.5） scheme. Results of all schemes for simulated flow distributions of upper ocean are similar to those of OFES in the North Pacific, but slight mismatches are found in flow directions and regions. The KPP scheme conducts the best simulation in comparison with OFES, and the KT scheme conducts the worst. A comparison in a typical section of the North Equatorial Cur- rent （NEC）, Kuroshio Current （KC）, and Mindanao Current （MC）, shows that the KPP scheme is superior and thus in agreement with previous research results. Using the three simulation results of different mixing schemes and OFES data, the seasonal volume transport of NEC, KC, MC, and MUC are estimated. Both the KPP scheme and OFES reflect the signal that the MC has maximum seasonal transport in spring （March to May） and minimum transport in fall （September to November）, and the MUC has an homologous trend. Furthermore, both the KPP scheme and OFES demonstrate the signal that the MC and NEC vary in the same phase, while the KC and MC vary in the same phase only in winter.