源区黑潮季节变异及其动力机制的数值研究

SEASONAL VARIATION AND DYNAMIC MECHANISM OF THE ORIGINATION OF THE KUROSHIO

应用POM2K模式对中国海黑潮区气候态平均环流进行了数值模拟。采用正交曲线网格,模式区域为太平洋海盆,特别的在中国海区域进行加密并较好的拟合了岸线;垂向分为21层,并在海表9层以上采用对数网格分布;采用COADS气候态月平均的风应力,并将模式的温度结果和MODIS月平均的SST数据进行同化,然后将模式模拟出的流量、海表高度异常同实测数据和卫星观测数据进行了对比验证,结果均显示模拟结果可信度较高。接着本文探讨了北赤道流分岔位置季节性的变化对源区黑潮流量的影响,结果表明,秋冬季节北赤道流分岔位置较靠北,源区黑潮流量较大,而春夏季节北赤道流分岔位置较靠南,黑潮流量较小。在此基础上,针对源区黑潮的动力机制进行了数值实验。实验中主要考虑了以下动力因子对源区黑潮季节性变化的影响:(1)风应力;(2)非线性;(3)黑潮的斜压敏感性,然后通过与控制实验的对比,讨论了不同的动力因素对吕宋海峡净流量和吕宋海峡上层环流场的影响。

Princeton Ocean Model in an orthogonal curvilinear coordinate was employed to simulate the circulation of Kuroshio. The model had 21 sigma levels in vertical direction includes the whole north Pacific, in high precision for well-fitting the coastline in East China Sea. Climatory monthly wind stress data from COADS were used as the sea surface boundary condition and the satellite sea surface temperature （SST） data are assimilated into the model. In addition, the simulated results of discharge and sea surface height were compared with the measured data and satellite observation data, respectively. The results show high credibility of the model. Moreover, the relationship between seasonal variation of the location of North Equatorial Current （NEC） bifurcation and the discharge from the Kuroshio origination area was studied. The results confide us that the discharge would be bigger when the location of NEC bifurcation is more northern in autumn and winter, or the opposite in spring and summer. On this basis, four sensitive experiments were employed to study the dynamics of the Kuroshio generation, in which the following factors were concerned： （1） wind stress （2） nonlinearity （3） sensitivity of the baroclinicity in origination area of the Kuroshio, for understanding the influence of different factors on the net discharge of LuzonStrait.