def stressBulk(u,S,rhoa=1.2,Cd=1.1e-3):
    """
    Calculate the wind stress component using the bulk exchange formulation
    
    Inputs:
        u - wind velocity x/y component [m s-1]
        S - wind speed magnitude [m s-1]
        Cd - drag coefficient
        rhoa - air density [kg m-3]
    """
    return rhoa*Cd*S*u