From AMS Glossary
Transport of a variable per unit area per unit time (i.e., a dynamic flux), but divided by the average air density (or in the case of heat flux, divided by the product of air density times specific heat of air at constant pressure).
The resulting kinematic flux has the same units as velocity times the variable being transported. For example, a vertical turbulent heat flux is
, while a vertical heat flux associated with mean wind is
, where w is vertical velocity, θ is potential temperature, an overbar denotes an average, and a prime denotes a deviation from the average. Kinematic fluxes are more closely related to meteorological variables that can be easily measured (such as temperature and wind) than are the associated dynamic fluxes (such as J m-2s-1). Statistically, kinematic fluxes are covariances.