Observing the onset of a magnetic substorm

Sep 02, 2014

Magnetic substorms, the disruptions in geomagnetic activity that cause brightening of aurora, may sometimes be driven by a different process than generally thought, a new study in the Journal of Geophysical Research: Space Physics shows.

Hwang et al. report observations using the Cluster spacecraft and ground-based magnetometers associated with the onset of a substorm. They saw two consecutive sudden jumps in the current sheet normal component of the magnetic field in the plasma sheet (the surface of that lies approximately in Earth's equatorial plane), separated by about 5 minutes. The first magnetic field enhancement, along with a series of other magnetic structures and a region of rarefied plasma, propagated outward away from Earth; the second magnetic field enhancement (dipolarization front) rapidly propagated toward Earth.

They argue that the observed sequence of events suggests that a disruption in the current sheet originated near Earth and moved toward the magnetotail, where it facilitated (the breaking and reconnecting of lines, which releases energy), creating conditions for substorm enhancement. This differs from the more commonly accepted scenario in which a substorm begins with magnetic reconnection in the magnetotail.

Explore further: The solar wind breaks through the Earth's magnetic field

More information: Hwang K.-J., M. L. Goldstein, T. E. Moore, B. M. Walsh, D. G. Baishev, A. V. Moiseyev, B. M. Shevtsov, and K. Yumoto (2014), A tailward moving current sheet normal magnetic field front followed by an earthward moving dipolarization front, J. Geophys. Res. Space Physics, 119, 5316, DOI: 10.1002/2013JA019657

add to favorites email to friend print save as pdf

Related Stories

The solar wind breaks through the Earth's magnetic field

Jun 10, 2014

Space is not empty. A wind of charged particles blows outwards from the Sun, carrying a magnetic field with it. Sometimes this solar wind can break through the Earth's magnetic field. Researchers at the Swedish ...

Ultrafast substorm auroras explained (w/ video)

Sep 06, 2011

(PhysOrg.com) -- From time to time, sudden releases of energy in Earth's magnetosphere lead to major disturbances that result in bright auroral displays over the planet's polar regions. These auroras are caused by a phenomenon ...

High-frequency flux transfer events detected near Mercury

Nov 13, 2012

The physical process that creates connections between the magnetic fields emanating from the Sun and a planet - a process known as magnetic reconnection - creates a portal through which solar plasma can penetrate ...

NASA Satellites Discover What Powers Northern Lights

Jul 24, 2008

(PhysOrg.com) -- Researchers using a fleet of five NASA satellites have discovered that explosions of magnetic energy a third of the way to the moon power substorms that cause sudden brightenings and rapid movements of the ...

Recommended for you

SDO captures images of two mid-level flares

14 hours ago

The sun emitted a mid-level flare on Dec. 18, 2014, at 4:58 p.m. EST. NASA's Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts ...

Why is Venus so horrible?

21 hours ago

Venus sucks. Seriously, it's the worst. The global temperature is as hot as an oven, the atmospheric pressure is 90 times Earth, and it rains sulfuric acid. Every part of the surface of Venus would kill you ...

Image: Christmas wrapping the Sentinel-3A antenna

23 hours ago

The moment a team of technicians, gowned like hospital surgeons, wraps the Sentinel-3A radar altimeter in multilayer insulation to protect it from the temperature extremes found in Earth orbit.

Video: Flying over Becquerel

23 hours ago

This latest release from the camera on ESA's Mars Express is a simulated flight over the Becquerel crater, showing large-scale deposits of sedimentary material.

Spinning up a dust devil on Mars

Dec 19, 2014

Spinning up a dust devil in the thin air of Mars requires a stronger updraft than is needed to create a similar vortex on Earth, according to research at The University of Alabama in Huntsville (UAH).

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.