Impacts of Regional Mixing on Circulations

Impacts of Regional Mixing on Circulations
in the Subtropical and Tropical Pacific Ocean
R. Furue1, Y. Jia1, J.P. McCreary1, K.J. Richards1, N. Schneider1, P. Müller2,
B.D. Cornuelle3, N. Martinez Avellaneda3, and D. Stammer4
1IPRC, 2U.
Figure 1. The model domain and each
subregion, in which diapycnal diffusivity is
separately increased from a background
value of 0.1 × 10-4 to 0.5 × 10-4 m2/s.
Hawaii, 3SIO, 4U. Hamburg
Figure 2. Salinity anomaly (shading, PSU) arising from Experiment
SE compared to the control run (CTL) and Montgomery
streamfunction from CTL on the 24.6 σθ surface at year 20.
An eddy-permitting model of the tropical and subtropical Pacific (Figure 1) is spun up under
climatological forcing. In separate experiments, the background diapycnal diffusivity within spatially
distinct subregions in Figure 1 is then increased. The impacts of those changes are assessed and the
processes to account for them diagnosed.
Figure 2 shows the salinity anomaly of Experiment SE (Figure 1) on a shallow isopycnal that intersects
the core of the Equatorial Undercurrent. Although the dynamical anomaly (such as density) is weak
outside the latitude band of SE (not shown), the salinity anomaly on isopycnals (“spiciness”), being a
passive tracer, is advected to the equator and upwells in the eastern equatorial Pacific, affecting seasurface temperature there.