The nonlinear force-free field ( NLFFF ) modeling has been extensively used as a tool to infer three-dimensional ( 3D ) magnetic field structure .
In this study , the dependency of the NLFFF calculation with respect to the initial guess of the 3D magnetic field is investigated .
While major part of the previous studies used potential field as the initial guess in the NLFFF modeling , we adopt the linear force-free fields with different constant force-free alpha as the initial guesses .
This method enables us to investigate how unique the magnetic field obtained by the NLFFF extrapolation with respect to the initial guess is .
The dependence of the initial condition of the NLFFF extrapolation is smaller in the strong magnetic field region .
Therefore , the magnetic field at the lower height ( < 10 Mm ) tends to be less affected by the initial condition ( correlation coefficient C > 0.9 with different initial condition ) , although the Lorentz force is concentrated at the lower height .