NOVELTY - The method involves determining (S10) mean profile of the marine flow and selecting (S11) eddy type representative of the turbulence. The eddy type is comprised of eddy size parameter and eddy strength parameter. The velocity signature and/or turbulent intensity signature, is determined (S12) for each selected eddy type. The determined signature is used to perform (S13) deconvolution of the mean profile, in order to determine probability density function as a function of the size parameter and/or strength parameter for each selected eddy type.    USE - Method for approximating quantity representative of turbulence in marine flow for marine or wind turbine.    ADVANTAGE - The use of simplified eddy profiles can improve the computational efficiency. The approximation process is less vulnerable to noise in the measurement data. The simulation of turbulence in geographic flow can be enabled with an acceptable computational effort. The convergence of turbulent spectra can be provided at the large scales, without being affected by haystacking. The approximation process can be applied in the field of wind and tidal power engineering for assessment of available resource, energy yield and structural loading characteristics. The process can be applied to computational simulation of aerodynamic and hydrodynamic loading on structures and/or devices present in a turbulent flow. The process can be integrated to many measurement data in order to provide net improvement in accuracy, robustness or representation of physical behavior in post-processed results. The peak loadings in normal usage can be ascertained even under extreme environmental loading scenarios. The predictions of energy yield of potential and existing turbine arrays can be provided.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) unit for approximating quantity representative of turbulence in marine flow; and    (2) computer readable storage media storing computer program for approximating quantity representative of turbulence in marine flow.    DESCRIPTION OF DRAWING(S) - The drawing shows a block flow diagram explaining the process for approximating quantity representative of turbulence in marine flow.    Step for determining mean profile of marine flow (S10)    Step for selecting eddy type representative of turbulence (S11)    Step for determining velocity signature and/or turbulent intensity signature for each selected eddy type (S12)    Step for performing deconvolution of mean profile (S13)    Step for performing convolution of probability density function with eddy signature for eddies of unit parameter value (S14)