- JpGU-AGU Joint Meeting 2017
Drastic deepening of the barrier layer off the western coast of Sumatra(4°S, 102°E, 800 m depth) due to the MJO passage observed duringDecember 2015 is investigated. The Research Vessel Mirai observationcaptured the drastic increase of isothermal depth from 20 m to 100 mfor only 4 days due to the westerly burst (5-9 m/s) associated withthe MJO. While, the mixed layer was deepened from 10 m to 40 m becauseof the strong stratification of the salinity in the ocean surfacelayer. As a result, the barrier layer depth was deepened from 10 m to80 m. This drastic deepening of the barrier layer was associated withthe increase of turbulent energy dissipation rate. Because the currentspeed in the surface layer off the western coast of Sumatra was veryslower (less than 20 cm/s) than that over the open ocean (more than 50cm/s), the vertical mixing due to the westerly burst could be a mainfactor for the barrier layer deepening.