J. Brenes et al., VARIATION OF THE GEOMAGNETIC-FIELD IN COSTA-RICA DURING THE TOTAL SOLAR ECLIPSE OF JULY 11, 1991, Earth, moon, and planets, 63(2), 1993, pp. 105-117
Ground measurements of the geomagnetic field. during the total solar e
clipse of July 11, 1991, were carried out at three sites in Costa Rica
located within the eclipse's path of totality. Near totality, there w
as a significant change in the total intensity. F. Its normal decrease
in the afternoon hours was interrupted during a period of about 45 mi
n, in which F varied very little. This was due mainly to a small varia
tion in horizontal intensity, H, during such a period. The departure o
f F from normal lasted about 100 min; its maximum departure was near 1
0 nT and occurred about 38 min after totality. The declination, D, als
o experienced a small change (about 2.3 min) during the total period o
f the eclipse. The vertical intensity, Z. and the inclination, 1, did
not show significant changes.