Author(s)

Shuai Meng

Corresponding Author

Shuai Meng

ABSTRACT

In the North Pacific Ocean, the North Equatorial Current (NEC) driven by the trade wind flows from the east to the west and bifurcates into the northward Kuroshio Current (KC) and southward Mindanao Current (MC) near the Philippine coast, comprising the NEC-MC-KC (NMK) current system, which is one of the regions with complex circulation system in the world ocean, and plays an important role in the variability of the global and regional ocean and climate. In this paper, the influence of El Nino on the interannual variations of NEC was investigated by utilizing the SLA (Sea Level Anomaly) data, SST (Sea Surface Temperature) data and sea surface wind field data fused by satellite. Firstly, 1.5-layer gravity reduction model can well express that the anomaly of the Northern Equatorial Current was related to the sea surface height anomaly, while the variations of El Nino can be described by nino3 index in first SST mode. The SLA difference value and nino3 index are respectively processed with a least square filter method. By comparing the trend of the two variables above and calculating the lead lag coefficient, it was concluded that there was a significantly positive lead and lag correlation between SLA and Nino3 index: the maximum correlation coefficient for Nino3 index lagging behind SLA difference at (135 ° E, 7° N) and (135 ° E, 10° N) is 0.9083; Lagging behind SLA difference at (170 ° E, 7° N) and (170 ° E, 10° N) is 0.818. This analysis strongly suggests that the transport of the northern equatorial current increases in strong El Nino years. Finally, further analysis found that the sea surface height anomaly, Ekman transport and west wind anomaly are closely related to the mechanism and results of El Nino affecting Northern Equatorial Current through the data of sea surface wind field and temperature.

KEYWORDS

Northern Equatorial Current transport, El Nino, Nino3 index, Least squares filtering, Lead lag coefficient, Ekman transport