【摘要】 根据实测资料(1986-1990年),分析了热带西太平洋(165°E,10°N～10°S)浮力频率的垂直分布和经向变化,讨论了浮力频率与海水稳定度和海洋内波位能的关系。分析结果表明,赤道海域浮力频率的垂直分布和经向变化具有明显的年际变化。其垂直分布的特点是:浮力频率的垂直变化与位温梯度dθdz的垂直变化相似。在ENSO前期或初期,浮力频率在垂直方向上的极大值达到最大,此时跃层最强,但其厚度最薄;在LaNi na期间,垂直方向的极大值明显小于ENSO前期和初期,此时跃层较厚,跃层强度次之;在ENSO末期,垂直方向上的极值介于上述两者之间。此时跃层厚度最为深厚,跃层强度最弱。浮力频率的经向变化是:在ENSO前期和初期,赤道海域的垂向极大值明显高于赤道外海洋;在LaNi na期间,它明显低于赤道外海洋;而在ENSO末期,则与赤道外海洋无显著差异;在8°N,有一个近乎定常的浮力频率峰值,几乎与ENSO或LaNi na的年际变化无关。更多还原

【Abstract】 Based on the observed data during 1986-1990,the longitudinal variabilities and vertical distributions of buoyancy frequency in the western tropical Pacific Ocean are analyzed to expound the relation of buoyancy frequency to seawater stability and potential energy of oceanic internal wave. It is shown from the analysis results that the longitudinal variabilities and vertical distributions of buoyancy frequency in the area have obvious interannual variabilities. Its vertical distribution features are that the vertical variations of buoyancy frequency are similar to those of potential temperature gradient dθ dz ; the maxima of buoyancy frequency in the vertical direction came to their multi-year maxima in the onset or earlier periods of an ENSO event when the thermocline became the thinnest and strongest; the maxima in the vertical direction during a La Nia event were significantly less than those in the onset and earlier periods of an ENSO event, and the thermocline at that time became thicker and less strong; the maxima in the vertical direction at the end of an ENSO event were in between the abovementioned two, and the thermocline at that time became the thickest and weakest. Its longitudinal variabilities are that the maxima in the vertial direction were significantly higher in the equatorial ocean than in the extraequatorial ocean in the onset and earlier periods of an ENSO event; those were significantly lower in the equatorial ocean than in the extraequatorial ocean during a La Nia event; there were no significant difference between the maxima in the vertical direction in the equatorial ocean and the extraequatorial ocean at the end of an ENSO event; an almost steady peak of buoyancy frequency was located at 8 °N and is almost independent of the interannual variabilities of ENSO or La Nia.更多还原