A study on the surface mixed layer based on the frontal Ekman theory

Research Summary

　In the upper ocean, a mixed layer with almost uniform density exists (Figure 1). Since heat, freshwater, and momentum are exchanged between the ocean and the atmosphere, the mixed layer plays an important role in ocean-atmosphere interactions. The principal investigator have revealed that changes in sensitivity to surface heat fluxes associated with changes in the mixed layer thickness plays a key role in generation of sea surface temperature anomalies. This mixed layer depth is determined by a complex interplay between surface heat fluxes, wind-induced turbulence, stratification at the bottom of the mixed layer, and Ekman currents/pumping (Figure 2). In this study, we examine the role of Ekman pumping in decadal climate variations in the North Pacific and nutrient supply, taking account of horizontal density gradient.

Fig 1: Schematic diagram of the mixed layer.

Fig 2: January climatology of the Ekman pumping in the northwestern Pacific (in 10-6 m/s).

Principal investigator:

Tomoki Tozuka 　Associate Professor, Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Physical Oceanography/Climate Dynamics
http://www-aos.eps.s.u-tokyo.ac.jp/~tozuka/indexe.html