def Udrift(amp,gAbs,c,d):
    """Calculates the 2nd order Stokes drift for a linear mode 

    Parameters
    ----------
    amp : float
        Description: Wave amplitude
    gAbs : float
        Magnitude of gravitational acceleration
    c : float
        Wave celerity
    d : float
        Water depth


    Returns
    --------
    float
        Magnitude of the mean velocity drift
    """
    return 0.5*gAbs*amp*amp/c/d