A dual-period response of the Kuroshio Extension SST to Aleutian Low activity in the winter season

• Published in: Acta oceanologica Sinica 2017-09, Vol.36 (9), p.1-9
• Main Authors: Yu, Peilong, Zhang, Lifeng, Liu, Hu, Liu, Xing, Zhu, Juan
• Format: Article
• Language: English
• Subjects: Advection; Aleutian low; Anomalies; Climatology; Curl (vectors); Datasets; Dipoles; Earth and Environmental Science; Earth Sciences; Ecology; Engineering Fluid Dynamics; Environmental Chemistry; Heat; Low; Marine & Freshwater Sciences; North Pacific Oscillation; Ocean-atmosphere interaction; Oceanography; Periodicities; Periodicity; Sea surface; Sea surface temperature; Seasons; Surface temperature; Variability; Velocity; Wind; Wind effects; Wind stress; Wind stress curl; Winter; 冬季; 北太平洋涛动; 周期响应; 振荡偶极子; 海温异常; 速度异常; 黑潮
• ISSN: 0253-505X; 1869-1099
• DOI: 10.1007/s13131-017-1104-1

Based on our previous work, the winter sea surface temperature（SST） in the Kuroshio Extension（KE） region showed significant variability over the past century with periods of ~6 a between 1930 and 1950 and ~10 a between1980 and 2009. How the activity of the Aleutian Low（AL） induces this dual-period variability over the two different timespans is further investigated here. For the ~6 a periodicity during 1930–1950, negative wind stress curl（WSC）anomalies in the central subtropical Pacific associated with an intensified AL generate positive sea surface height（SSH） anomalies. When these wind-induced SSH anomalies propagate westwards to the east of Taiwan, China two years later, positive velocity anomalies appear around the Kuroshio to the east of Taiwan and then the mean advection via this current of velocity anomalies leads to a strengthened KE jet and thus an increase in the KE SST one year later. For the ~10 a periodicity during 1980–2009, a negative North Pacific Oscillation-like dipole takes2–3 a to develop into a significant positive North Pacific Oscillation-like dipole, and this process corresponds to the northward shift of the AL. Negative WSC anomalies associated with this AL activity in the central North Pacific are able to induce the positive SSH anomalies. These oceanic signals then propagate westward into the KE region after 2–3 a, favoring a northward shift of the KE jet, thus leading to the warming of the KE SST. The feedbacks of the KE SST anomaly on the AL forcing are both negative for these two periodicities. These results suggest that the dual-period KE SST variability can be generated by the two-way KE-SST-AL coupling.