ON THE ANOMALOUS FEATURES OF THE GEOMAGNETIC QUIET-DAY FIELD VARIATIONS AT NAGPUR, INDIA

The quiet-day geomagnetic field variation data from the recently commi ssioned Nagpur geomagnetic observatory, which has augmented the curren tly active latitudinal chain of Indian magnetic observatories, are ana lysed for the year 1993. The variations for diurnal frequencies (Sq) r ecorded at Nagpur do not follow the expected trend with latitude. This is most conspicuous in the northward horizontal (X) component. The an omalous behaviour at Nagpur is also seen in the diurnal harmonic ampli tudes when compared with those of the neighbouring stations Alibag (so uth of Nagpur) and Ujjain (north of Nagpur). This behaviour is attribu ted to the presence of electrically conducting anomalous sources in th e vicinity of Nagpur. The anomalous internal source is inferred to be located at relatively shallower depths and is highly localized.