Deep-reaching thermocline mixing in the equatorial pacific cold tongue

作者：Liu, Chuanyu^*; Kohl, Armin; Liu, Zhiyu; Wang, Fan; Stammer, Detlef

来源：Nature Communications, 2016, 7(1): 11576.

DOI：10.1038/ncomms11576

• TROPICAL INSTABILITY WAVES
• UPPER-OCEAN
• SHEAR INSTABILITY
• SURFACE-LAYER
• SCALE SHEAR
• FINE-SCALE
• TURBULENCE
• OSCILLATIONS
• CYCLE
• FLOW

Vertical mixing is an important factor in determining the temperature, sharpness and depth of the equatorial Pacific thermocline, which are critical to the development of El Nino and Southern Oscillation (ENSO). Yet, properties, dynamical causes and large-scale impacts of vertical mixing in the thermocline are much less understood than that nearer the surface. Here, based on Argo float and the Tropical Ocean and Atmosphere (TAO) mooring measurements, we identify a large number of thermocline mixing events occurring down to the lower half of the thermocline and the lower flank of the Equatorial Undercurrent (EUC), in particular in summer to winter. The deep-reaching mixing events occur more often and much deeper during periods with tropical instability waves (TIWs) than those without and under La Nina than under El Nino conditions. We demonstrate that the mixing events are caused by lower Richardson numbers resulting from shear of both TIWs and the EUC.

• 出版日期2016-5
• 单位近海海洋环境科学国家重点实验室; 厦门大学; 中国科学院海洋研究所