Abstract: Since Deardorff (1966) derived the counter-gradient term contribution, a good representation has been searched for this term. An inverse problem methodology is be used to identify this property. The inverse analysis is performed minimizing an objective function: the square difference between experimental and model data added to a regularization function. Two regularization functions are used, second-order maximum entropy and Tikhonov regularization of second-order. The scheme is tested with synthetic noise data. A new formulation for the counter-gradient is also presented.