Trends in the Secular Variation of the Earth's Magnetic Field

P231 TRENDS IN THE SECULAR VARIATION OF THE EARTH'S MAGNETIC FIELD DANIEL MARTINI 1 and ALPAR KORMENDI 2 1 Summary 1 A world-wide network has been continuously monitoring the secular change of the Earth’s magnetic field. More than 70 countries operate about 200 observatories throughout the world nowadays. The database which has been collected by the observatories gives us a chance to make a study of the temporal behaviour of the Earth’s magnetic field and to understand the features of these and related phenomena. Precise removal of the temporal variations is fundamental in any high-accuracy magnetic survey and magnetic map