加利福尼亚附近的海温强迫及其与北太平洋年代际振荡的可能联系

SST Forcing off California Coast and Its Relationship to the Decadal Variation of North Pacific

本文利用1958~2018年期间海表面温度(SST)异常和湍流热通量异常变化的关系,探讨了其与北太平洋年代际振荡(PDO)相关的年际和年代际时间尺度上在不同海域的海气相互作用特征。结果表明:在年际尺度上,黑潮—亲潮延伸区(KOE)表现为显著大气强迫海洋,赤道中东太平洋表现为显著海洋强迫大气;在年代际尺度上,PDO北中心表现为大气强迫海洋,加利福尼亚附近则表现为显著海洋强迫大气。进一步分析表明:加利福尼亚附近区域是北太平洋准12年振荡的关键区域之一,与PDO准十年的周期类似,加利福尼亚附近的冷(暖)海温对应其上有反气旋(气旋)型环流,赤道中太平洋海水上翻和北太平洋东部副热带区域经向风应力的变化是北太平洋准12年振荡的另外两个重要环节。

This study explores the characteristics of interannual and interdecadal air–sea interactions related to the Pacific Decadal Oscillation(PDO) over the different regions of the North Pacific based on the relationship between turbulent heat flux and sea surface temperature(SST) anomalies during 1958–2018. The results show that the atmosphere directly drives SST anomalies over the Kuroshio–Oyashio Extension and the SST anomalies force atmospheric circulation over the equatorial central and eastern Pacific on the interannual scale. On the interdecadal scale, SST anomalies are mainly driven via atmospheric circulation over the north center of PDO. However, the ocean is very important in forming SST anomalies off the California coast. Further analysis shows that the area off the California coast is one of the key areas of quasi-12-year oscillation in the North Pacific. The period is similar to the decadal oscillation of PDO. The anticyclone(cyclone) circulation off the California coast may be forced via the cold(warm) SST anomalies off the California coast.The other two important parts in the quasi-12-year oscillation in the North Pacific are the upwelling of the equatorial central Pacific and meridional wind stress anomalies in the subtropical eastern North Pacific.