Bian G.,Dalian Naval Academy |
Bian G.,Wuhan Naval University of Engineering |
Bian G.,Key Laboratory of Hydrography and Cartography of PLA |
Xia W.,Dalian Naval Academy |
And 13 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica)
The geomagnetic diurnal variation is the main influence in marine magnetic survey, especially in offshore and large areas. The multi-station method is the main technique to deal with the geomagnetic diurnal variation correction. However, to diminish the difference between the magnetic field data wand multi-station data, the correctional datum of the secondary station must be reduced to the main station. In marine surveys, the least squares fitting method has been applied in the interploation of the height of the tide. Considering the similarity of the influence mechanism of the tidal variation and the geomagneitc diural variation, the the least squares fitting method has been introduced in the datum reduction. The datum of the secondary station can be corrected, which is decieded by the expansion and contraction of the amplitude, the translation of the time (phase) of the diurnal variation of the main station, and the the residual error of the diurnal variation correction of the main and secondary station is minimum with the least square method. The validity of the method has been testified by the observed synchronous data of the multi-station. The results show that the least squares fitting method can be applied when the characteristics of the diurnal geomagnetic variations of the stations are similar, which requires a short synchronous observation period. Otherwise the synchronous correction method should be qualified. The conclusion shows that the least squares fitting method can be effectively applied in the datum reduciton with multi-station diurnal variation correction, therefore the differenceof the magneitc field which is caused by datum can be diminished and the geomagnetic diurnal variation correciton precision can be improved in magneitc surveys in offshore and large areas. Moreover the reduciton methd must be adjusted to the need of the practice. In addition, the least squares fitting method can be applied in the determination of the time difference and the correction value interpolation. ©, 2015, Science Press. All right reserved. Source