The Recognition of Oceanic Kelvin Waves According to Westerly Wind Bursts

Abstract Based on the criteria of oceanic Kelvin wave events in the equatorial Pacific on the pentad-monthly timescale, this study analyzed the optimal statistical relationship between westerly wind bursts (WWBs) and oceanic Kelvin waves in the equatorial Pacific through lead-lag analysis. Under the influence of sustained westerly wind anomaly (WWA) (60-day mean), it can effectively cause the positive sea temperature anomaly (60-day mean) in the upper equatorial Pacific Ocean after 20 days. However, under the influence of continuous easterly wind anomaly (EWA) (30-day mean), the negative sea temperature anomaly (30-day mean) in the upper ocean can be effectively caused after 30 days. In addition, WWBs near the international dateline (150 °E-170 °W) corresponds well to the 20°C isotherm depth anomaly in the equatorial Mid-Eastern Pacific (160 °W-100 °W). WWAs in the western Pacific (west to 170 °E) can lead to thermocline change at 150°W and stimulate the propagation of the Kelvin wave eastward to the equatorial eastern Pacific from March to August. During the mature period of El Niño–Southern Oscillation (ENSO) (September to February in the following year), Bjerknes positive feedback is formed near the international dateline with the coupling effect of WWBs, sea surface temperature (SST) and thermocline in the equatorial Eastern Pacific. The contemporaneous correlation reaches peak between the WWA in the equatorial western Pacific (near 170 °E) and the 20°C isotherm depth anomaly in the equatorial eastern Pacific (near 110 °W).