THE ANNUAL VELOCITY VARIATION OF GEOMAGNETIC FIELD WITHIN HEBEI PROVINCE IN RECENT YEARS

Based on the z component's absolute value data of 8 geomagnetic observatory in Hebei province,the characters and law of geomagnetic field variation in recent years are analyzed.The results show:1.the z component of geomagnetic field increased annually with power series from 1970s,and is increasing at present;2.The annual velocity experienced a process of from increasing annually to decreasing annually,and it reached the hump during 1993 1994;3.The annual velocity variation has a decreasing tendency from southeast to northwest in space.