六套海洋模式模拟热带西太平洋深层环流结果的对比分析

借助于六套海洋模式资料,本文初步分析了热带西太平洋深层环流的基本特征。与气候态数据集WOA13相比,水深3000m层除HYCOM以正温度偏差为主外,其余模式均为负温度偏差,且随着深度增加偏差幅度变大。盐度偏差方面,HYCOM和OFES以正偏差为主,其余模式以负偏差为主。温盐偏差在各个深海海盆中的时间变化趋势不尽相同,且与实际观测结果存在较大差异。水深1000—3000m以纬向东西向交替变化的射流为主。3000—5000m的纬向流速减小,形成海盆内环流,不同海盆之间可通过深水通道进行海水交换。3000m以深的关键深海通道的输运通量存在明显的季节变化,甚至不同季节流向也不一致,而海盆内的环流形态受制于位涡收支积分约束方程,进而也表征出季节变化的特征,即不同季节海盆内的环流主要旋转形态不同。在分析了初始温盐场、潮汐及其他要素对深海环流的影响后,本文为日后构建适合热带西太平洋深海环流研究的模式提供了建议。

DEEP-LAYER CIRCULATIONS IN TROPICAL WESTERN PACIFIC OCEAN BASED ON SIX OCEAN MODELS OUTPUTS

We conducted a preliminary analysis on deep-layer circulation in the tropical western Pacific using six ocean models outputs. In comparison with WOA13, the HYCOM''s deep temperature deviation at 3000 m is mainly positive, while other five models'' are negative. The deep temperature deviations increase with depth. The deep salinity deviations of HYCOM and OFES are mainly positive, while other models'' are mainly negative. Both the temporal trends of mean temperature and salinity deviations are different from the observations. The currents between 1000 and 3000m are dominated by alternating westward and eastward zonal jets. The zonal velocity decreases quickly below 3000m, and the circulations are separated by different basins between 3000 and 5000m, but the seawater exchange can take place through deep-layer passages among basins. The transport in deep-layer passages shows seasonal variability; moreover, the direction of current in some deep layers could be opposite in different seasons. The pattern of circulation is controlled by potential vorticity constraint equation, and thus also shows seasonal variation, indicating temporal difference in the form of major rotations in these basins. In addition, we discussed the impacts of T/S initial value, tide, and other factors on the deep circulations, and proposed suggestions for future improvement in the modeling.