Time scale of the largest imaginable magnetic storm Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
08 Jan 2013
Received: 29 April 2012 – Revised: 19 November 2012 – Accepted: 29 December 2012 – Published: 08 January 2013Abstract. The depression of the horizontal magnetic field at Earth's equator for the
largest imaginable magnetic storm has been estimated (Vasyliūnas, 2011a)
as −Dst ~ 2500 nT, from
the assumption that the total pressure in the magnetosphere (plasma plus magnetic
field perturbation) is limited, in order of magnitude, by the minimum pressure
of Earth's dipole field at the location of each flux tube. The obvious
related question is how long it would take the solar wind to supply the energy
content of this largest storm. The maximum rate of energy input from
the solar wind to the magnetosphere can be evaluated on the basis either of magnetotail stress
balance or of polar cap potential saturation, giving an estimate of the
time required to build up the largest storm, which (for solar-wind and
magnetospheric parameter values typical of observed superstorms) is roughly
between ~2 and ~6 h.
Citation: Vasyliūnas, V. M.: Time scale of the largest imaginable magnetic storm, Nonlin. Processes Geophys., 20, 19-23, doi:10.5194/npg-20-19-2013, 2013.