Variation of the Horizontal Force near the Magnetic Equator

Abstract

SINCE November 1955 a magnetic observatory has been in operation at University College, Ibadan (lat. 7° 26′ N., long. 3° 54′ E.), 2° 34′ south of the magnetic equator. Between November 25, 1956, and January 22, 1957, photographic recordings of the variation of the horizontal component H of the Earth's magnetic field were made for a period of a week at each of nine field stations between lat. 6° 36′ N. and 13° N.; that is, between about 3° north and 3° south of the magnetic equator. Records were taken with a simple temperature-compensated variometer, and were supplemented by frequent QHM readings. The whole period was relatively quiet magnetically, and the records at all stations included a number of quiet days.