• I A Ansari

      Articles written in Journal of Earth System Science

    • Wave packet structure and phase jumps in low latitude Pc3 geomagnetic pulsation

      I A Ansari B J Fraser K J McLean

      More Details Abstract Fulltext PDF

      An array of four low latitude induction coil magnetometer stations has been used to study the spatial and temporal characteristics of Pc3 pulsations over a longitudinal range of 17° atL=1·8 to 2·7 in south-east Australia. A preliminary study of individual Pc3 wave packet structure at the azimuthal stations has established the existence of phase jumps between wave packets at low latitudes similar to those observed at synchronous orbit and at higher latitude ground stations. However there did not appear to be any obvious pattern in phase jump occurrences between stations or signal components.

    • Spectral characteristics of low latitude Pc3 geomagnetic pulsations in south-east Australia

      I A Ansari B J Fraser K J McLean

      More Details Abstract Fulltext PDF

      Geomagnetic pulsations in the Pc3 period range (10–45 sec) were recorded simultaneously in south-east Australia using an array of four low latitude induction coil magnetometers over a longitudinal range of 17° atL=1·8 to 2·7. Geomagnetic data from March 25 to September 21, 1982 were digitized and spectral studies were carried out from Grey scale digital (GSD) dynamic spectra and contour sonagrams. Similar wave spectra were generally seen at the three stationsWM, BH andNC in the same latitude with Pc3 waves mostly being observed in the 40–45 mHz band. In addition the higher latitude station (LN) also showed lower frequency Pc4 bands (≈ 10mHz) on some days but higher frequency bands (60–80mHz) on others. Sometimes completely different wave frequencies were observed on theX andY components with the stations in the same latitude generally showing similar spectra on the corresponding components. Dynamic spectra also indicated that wave energy often turned off and on abruptly over short intervals of time implying solar wind control and Pc3 pulsation activity. A band harmonic structure was occasionally seen in wave spectra at the azimuthal stations mainly on theX component during the local afternoon with a harmonic spacing (Δf) of ≈ 10 mHz.

  • Journal of Earth System Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.