Figure 4 . Histogram of mixing efficiency (or correlation coefficient between meridional velocity and temperature) from the cross-slope mooring section in 113°E. “Down-gradient” denotes the correlation by southward velocity, and “up-gradient” means the correlation by northward velocity. Since the downgradient velocity must direct southward (shoreward), “up-gradient” possibly reflects transient events irrelevant to the climatological eddy condition. Hence, in addition to the whole mean (black line) and the previous estimate (dashed line; 0.16), the mean value only for the “down-gradient” is also presented (gray line).