北太平洋波浪输运和西边界流的季节变化

西边界流输运可以用Sverdrup理论推算出来.本文首先利用ECMWF再分析风场数据,计算了44年的月平均的风应力旋度及Sverdrup体积输运,在北太平洋3条纬度上对Sverdrup体积输运进行积分,得到Sverdrup体积输运的季节变化,从中发现,在向赤道流动的方向上,Sverdrup体积输运在冬季存在最大值,夏季存在最小值;同样利用ECMWF再分析波浪数据,计算了44a的月平均的Stokes体积输运,在相同纬度上对Stokes体积输运进行积分,得到Stokes体积输运的季节变化,从结果中发现,在向赤道流动的方向上,Stokes输运在冬季存在最大值,在夏季存在最小值.在本文中设定R=T_(st)/T_(sv)×100%,T_(st)为Stokes体积输运,T_(sv)为Sverdrup体积输运,发现Stokes输运和Sverdrup输运存在同位相的季节变化,并且(-R)冬季平均值在5%以上,年平均值在2%～3%左右,从而推断出波浪诱导的输运对Sverdrup输运,既对西边界流有不可忽视的贡献.

THE SEASONAL VARIATIONS OF THE NORTHERN PACIFIC WAVE TRANSPORT AND WESTERN BOUNDARY CURRENT

The volume transport of the western boundary current can be inferred by use of the Sverdrup balance. By employing 44 years reanalysis wind stress data and surface wave data from European Centre for Medium-Range Weather Forecasts (ECWMF), the averaged seasonal variations in three Sverdrup transports across 32.5°N, 30°N, and 27.5°N are estimated. It is found that three Sverdrup transports have almost similar seasonal variation with a maximum in winter and a minimum in summer. In addition, the averaged seasonal variations in three Stokes volume transports are also calculated based on the ECWMF surface wave data, it shows a similar tendency of the annual change in overall Sverdrup transports. The annual averaged ratios of Stokes transport to Sverdrup transports are about 2 to 3 percent. From these results, it can be inferred that wave transports make a great contribution to Sverdrup transports.