资源环境科技发展态势分析平台

Prominent intraseasonal variability (ISV) of ocean currents was detected by two subsurface moorings deployed at 140 degrees E, 2 degrees N, and 4.7 degrees N during 2014-2018 and shown to be largely induced by westerly wind bursts (WWBs) associated with passages of Madden-Julian oscillations (MJOs). The North Equatorial Countercurrent between 60 and 200 m is enhanced (attenuated) by 6-8 cm/s prior (subsequent) to the WWB. Current anomalies below 300 m are as large as 2-3 cm/s, close in magnitude to the mean velocities of the North Equatorial Subsurface Current and North Subsurface Countercurrent. The ISV in the upper 600 m shows a vertical dipole structure at 2 degrees N and vertically coherent anomalies at 4.7 degrees N. Further analysis combining satellite data reveals local recirculation structures generated by wind-forced Rossby waves. Ocean model experiments confirm the importance of the MJO's wind forcing in causing these subsurface ocean ISVs.