Response

摘要

In my perspective (11 MAY, P. 838), I pointed out that even in well-developed, isotropic turbulence, mixing efficiency is not a global constant. It depends critically on the length scale at which turbulent energy is imparted to the flow compared with the buoyancy length scale. In most physical oceano-graphic applications, this scale dependence goes unnoticed because these length scales are generally commensurate and mixing efficiency is near its maximum. This is not true for biomixing, and studies that ignore mixing efficiency (1-3) in all likelihood overstate the case for the biosphere's role in mixing the world's oceans.