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Nocturnal variations of geomagnetic horizontal field at equatorial stations
Author(s) -
Rastogi R. G.,
Chandra H.,
James M. E.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl02390
Subject(s) - sunset , sunrise , midnight , nocturnal , earth's magnetic field , ionosphere , atmospheric sciences , geology , f region , electric field , geophysics , magnetic field , physics , astronomy , quantum mechanics
The nocturnal variations of the horizontal component (H) of the geomagnetic field at equatorial stations Koror, Trivandrum, Addis‐Ababa and Ibadan during any of the seasons of the period 1958–59 showed a steady decrease after sunset throughout the nighttime hours. However, at Huancayo a steady decrease after sunset to sunrise is seen only during the D‐months. During the J and E months decrease is seen after sunset till about 22–23 hr and a slow and steady increase from midnight hours to sunrise. The nocturnal variations of H field at Huancayo show a remarkable similarity with the corresponding variations of the horizontal electric field in the ionosphere as determined by the Doppler shifts of backscatter echoes from the E and F layers over Jicamarca. Thus, genuine changes in the equatorial electric field and current in the ionosphere over the American sector during the nighttime hours are clearly indicated.