2017 年 29 巻 1 号 p. P3-P18
We present the comparison of two leveling methods proposed by Wessel (2010) and Ishihara (2015) using the geomagnetic data in the Gulf of Aden. The data used in this study were obtained in the cruises from 1961 to 2001. The data collected over a long period of time may result in large crossover errors. The reduction of crossover errors is one of the most important and imperative issues to make magnetic anomaly contour maps. The method proposed by Wessel (2010) reduces crossover errors at intersections among tracks by an appropriate linear model. That proposed by Ishihara (2015) consists of adjusting each measurement using the weighted spatial average of its neighboring data and subsequent temporal filtering. We compared the two methods for three areas in the Gulf of Aden; one area of the dense data coverage around the spreading center and two areas of the sparse data coverage off the spreading center. Our study concluded that the method proposed by Ishihara (2015) reduced crossover errors more effectively than that by Wessel (2010).