Bifactor weight determination method based on direction and distance in geomagnetic data assimilation

In the geomagnetic data assimilation, we analyze the weight determination weakness of the direct average method, reverse distance weighting average method and latitude difference weighting average method which are widely used in the previous work. Considering the geomagnetic field strength has a close relationship with the changing of latitude, we propose a bifactor weight determination method based on the direction and distance. Concretely, it not only utilizes the distances among the geomagnetic observatories but also takes into account the changes from the latitude and longitude directions simultaneously, which assigns the different weights to the above three factors to improve the precision of geomagnetic data assimilation and obtain the more precise diurnal variation correction for the satellitic, airborne and seaborne geomagnetic measurement data. Furthermore, we use the geomagnetic observatory data supplied by Intermagnet website to validate the proposed method. The experimental results demonstrate that the proposed method is superior to the existing methods in the accuracy of calculation result. Thus, this paper proposes a novel and reliable weight determination method which has a potential application in the diurnal variation correction of geomagnetic measurement data in the regions where the ground survey is implemented difficultly.