Stepped Inversion Of 2D Magnetic Data

Step magnetic inversion procedure in which invariant quantities with respect to source parameters are inverted sequentially to give(1) shape cross section, (2)magnetization intensity, and(3)magnetization direction for a 2D (elongated) magnetic source. The adveantage of this mothod is that it invariance with both magnetization intensity and direction, as such, it can be used in shape reconstruction with arbitrary magnetization (intensity and direction), then, its magnetization intensity is estimated by fitting the total gradient of the magnetic anomaly, and the magnetization direction is determined by fitting the magnetic anomaly.The original is based on the previous research works (Soraya, 2007) , and conducts more detailed analysis and research to the step magnetic inversion. Fistly, during the frequency domain processing, using the method of upward continuation solve the problem of high-frequency interference. Secondly, we solve the issue of zero frequency when we obtain the magnetic component in the Fourier domain. Thirdly, we detailed research the general characters of the shape function S, and sovle the effect of regional background in calculating S by adding a constant to the magnetic components respectively. Forthly, improving the objective function by changing the magnitude and unit of shape function to enhance the effect of S, which improving both the speed and accuracy of inversion. Fifthly, we apply the improved controlled random search(ICRS) for shape reconstruction. Then we use Fortran90 to program the homologous programs, and try to calculate a lot of modles, and obtain comparatively satisfactory result. Finally, stepped inversion is used to model a ariborne magnetic anomaly from South China Sea, and obtain the consistent result with the other mothed.