Bulk mass exchange between an interface-emitting or -absorbing gas and a turbulent flow — represented by a gas transfer velocity — is commonly described as an empirical function of a mean velocity at some reference height. Such a representation, while of practical significance and continued use in large-scale climate models, misses the most important ingredient to the transfer process itself: turbulent eddies. The connection between energy content in eddies (a microscopic state) and gas transfer velocities (a macroscopic outcome) may be viewed as analogous to a fluctuation-dissipation relation, except for turbulent flows.
Bulk mass exchange between an interface-emitting or -absorbing gas and a turbulent flow — represented by a gas transfer velocity — is commonly described as an empirical function of a mean velocity at some reference height. Such a representation, while of practical significance and continued use in large-scale climate models, misses the most important ingredient to the transfer process itself: turbulent eddies. The connection between energy content in eddies (a microscopic state) and gas transfer velocities (a macroscopic outcome) may be viewed as analogous to a fluctuation-dissipation relation, except for turbulent flows.
