Mechanisms controlling mixed-layer temperature variability in the eastern tropical Pacific on the intraseasonal timescale

Its impacts on ocean mixed-layer temperatures (MLT) in the eastern tropical Pacific Ocean (ETPO) are not well-understood. A previous study of mooring data at (110°W, EQ) implies vertical advection forced by MJO-generated Kelvin waves is important to ETPO intraseasonal MLT; another, based on model output over (120-100°W, 3°S-3°N), indicates meridional advection dominates.

We analyze an ocean state estimate at (110°W, EQ) and find combined subsurface processes, including a notable vertical advection component like that expected from MJO-forced Kelvin waves, dominate. However, when averaged over (120-100°W, 3°S-3°N), subsurface processes and horizontal advection are both important, and effects of thermocline forcing (e.g., Kelvin waves) are small compared to those by local wind driven mixing and horizontal advection.