The streamwise Kolmogoroff constant

Observations over grassland of the turbulent kinetic energy in a band of frequencies in the inertial subrange of the spectrum of the streamwise wind component are related to the stress indicated by the wind profiles. The object is to determine the effective Kolmogoroff constant, _UB , which accords with the assumption of balance between turbulent energy production and dissipation. The mean from 60 half-hour runs made under stability conditions ranging from neutral to moderate instability is _UB = 0.62.This result is compared with those from other studies; four over grassland and six over the sea or a lake. There is no significant difference between the means of the land and sea values, but the latter are more scattered, partly because of difficulties in securing suitable exposure of the instruments for the stress measurements. The mean value from all ten sets of observations is _UB = 0.59 ± 0.025. So the dissipation method should be capable of giving the drag coefficient of the sea in strong winds with an uncertainty of no more than about 10%.