|Geomagnetic Principal Magnetic Storms
|The abbreviations used for observatory names are as follows: GEOMAGNETIC OBSERVATORIES
Code Station Geomagnetic Latitude ABG Alibag AMS Martin de Vivie. These data present
the principal magnetic storms for the month as reported by several observatories through
cooperation with the International Association of Geomagnetism and Aeronomy (IAGA).
These are the data formerly published in the Journal of Geophysical Research. They
are now, however, grouped by the storm rather than by station. The geomagnetic latitude
of the station is indicated. The beginning time is given to the hour and minute in
UT. The tupe of sudden commencement, if any, together with its magnitude in each element
D, H or Z is next in the format: sc = sudden commencement; sc* = small initial impulse
followed by main impulse (in this case the amplitude is that of the main pulse only,
neglecting the initial brief pulse); dots in these columns represent a stomr with
gradual commencement; blanks indicate no data entries. Signs of amplitudes of D and
Z are taken albegraically; D reckoned positive if toward the east and Z reckoned positive
if vertically downward. In the next columns the day and the three-hour periods on
that day when the K index reached its maximum are given followed by the K index value.
In the next three columns the maximum ranges in D, H and Z during the storm are given.
The ending time is given only to the nearest hour. This is the time of cessation of
reasonably marked disturbance movements in the trace. More specifically, it is the
time when the K index measure has diminished to 2 or less for a reasonable period.
For each date the data are listed in north-to-south geomagnetic latitude order.