吕宋海峡水交换季节和年际变化特征的数值模拟研究

利用ROMS(Regional Ocean Modeling System)建立了一套覆盖西北太平洋的涡尺度分辨率环流模型,并对吕宋海峡附近的环流进行了模拟研究。结果表明,吕宋海峡120.75°E断面净流量季节变化显著,全年均为西向输运,6月份达到最小,为0.40×106 m3/s,然后逐渐增大,在12月份达到最大,为6.14×106 m3/s,全年平均流量为3.04×106 m3/s。在500 m以浅,秋、冬季都有明显的黑潮流套存在,并伴有黑潮分支入侵南海,而春、夏季黑潮南海分支减弱或消失,黑潮入侵不明显。在500 m以深,冬、春季,吕宋海峡以东有非常明显的南向流存在,流速约10 cm/s,而到了夏、秋季该南向流出现明显的减弱,黑潮与南海的水交换主要通过吕宋海峡以北的吕宋海沟进行。在垂向结构上,120.75°E断面浅层呈多流核结构,并且流核的位置和强弱受黑潮的季节性变化影响显著,深层流的季节变化不大。在年际尺度方面,吕宋海峡年际体积输运量异常与Niño3.4滞后6个月相关系数达到41.6%,吕宋海峡水交换与ENSO现象有较为显著的正相关关系,并存在2~3 a和准8 a周期的年际变化。

Numerical study of seasonal and interannual variation of circulation and water transports in the Luzon Strait

The Northwest Pacific model, a regional (1/20)°eddy-resolving ocean general circulation model, is adapted to study the seasonal and inter-annual variation of circulation and water exchange in the Luzon Strait (LS) based on the ROMS (Regional Oceanic Model System). The LS is the main channel, through which the SCS exchange water with the West Pacific Ocean. The seasonal variation in the Luzon Strait Transport (LST) is found to be significant; and LST is westward throughout the year. The LST through the 120.75°E Section reaches the minimum in June of 0.40×10⁶ m³/s and maximum in December of 6.14×10⁶ m³/s. The mean LST is estimated to be 3.04×10⁶ m³/s. In the upper-layer (0-500 m), the Kuroshio Intrusion takes the shape of Kuroshio Loop with a South China Sea branch of Kuroshio in winter and autumn, while the Kuroshio Intrusion is non-significant with the disappearance of South China Sea branch of Kuroshio in spring and summer. In the deep-layer (>500 m), the southward current of LS is significant in winter and spring with 10 cm/s, while the current become weak in summer and fall. The Luzon Trench is the main channel through in the deep-layer. Multi-core structure is a characteristic of the vertical transport pattern in the LS, with several cores in its southern part and only one core in its northern part. The lag correlation coefficient with six months between LST and Niño 3.4 can reach to 41.6%, which is closely related to the remote influence of ENSO, and there are 2-3 years and 8 years cycle in the inter-annual variation of LST in addition.