Abstract

The geomagnetic crochets recorded at Alibag, Annamalainagar and Trivandrum by the solar flare of 12 July 1961 are examined with reference to the normal Sq, currents prevailing over these stations at the time of the solar flare. The large change in declination at Alibag and changes in horizontal intensity at Annamalainagar and Trivandrum indicate that the solar flare current system is an intensification of the normal Sq current system. Evidence in favor of this conclusion is sought for in the solar flare effects recorded at Alibag by the flares of 19 November 1949, 19 March 1948, and 14 October 1953. A plot of the amplitudes of the solar flare effects in the horizontal intensity at Alibag, Annamalainagar and Trivandrum during the period 1958–59 shows daytime enhancement of the flare effect at the latter two stations only, indicating a close connection between the crochet current system and the electrojet. It is therefore established that the crochet current system is an enhancement of the normal Sq current system.

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