Related Experiment Video
Updated: Jun 1, 2026
08:01
Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Magnetosphere sawtooth oscillations induced by ionospheric outflow
O J Brambles1, W Lotko, B Zhang
1Thayer School of Engineering, Dartmouth College, Hanover, NH, USA. ojbrambles@dartmouth.edu
Science (New York, N.Y.)
|June 4, 2011
Summary
Earth's magnetosphere exhibits sawtooth oscillations, driven by solar wind interactions. Ionospheric O(+) outflows are key, ejecting plasma and causing magnetic field changes.
Area of Science:
- Space Physics
- Geophysics
- Plasma Physics
Background:
- Earth's magnetosphere exhibits periodic sawtooth oscillations.
- These oscillations are planetary-scale and occur every 2-4 hours.
- The solar wind-magnetosphere-ionosphere (SW-M-I) interaction powers these oscillations.
Purpose of the Study:
- Investigate the role of ionospheric O(+) outflows in generating sawtooth oscillations.
- Understand the mechanisms driving the magnetospheric dynamics during these events.
Main Methods:
- Utilized global simulations of geospace.
- Analyzed the impact of ionospheric O(+) outflows on the inner magnetosphere.
Main Results:
- Ionospheric O(+) outflows were identified as a generator of sawtooth oscillations.
- Outflowing ions increase pressure, distending the nightside magnetic field.
- Exceeding an outflow threshold leads to plasmoid ejection and magnetic field dipolarization.
Conclusions:
- Ionospheric O(+) outflows are crucial for sawtooth oscillation generation.
- The SW-M-I interaction strength controls outflow fluence and oscillation period.
- Magnetospheric dynamics shift between quasi-steady convection and dynamic ejection events.
Related Concept Videos
01:28Magnetostatic Boundary Conditions
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
01:19Magnetic Field Lines
The representation of magnetic fields by magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. Each of the magnetic field lines forms a closed loop. The field lines emerge from the north pole (N), loop around to the south pole (S), and continue through the bar magnet back to the north pole.
Magnetic field lines follow several hard-and-fast rules:
Magnetic field lines follow several hard-and-fast rules:
01:06Forced Oscillations
When an oscillator is forced with a periodic driving force, the motion may seem chaotic. The motions of such oscillators are known as transients. After the transients die out, the oscillator reaches a steady state, where the motion is periodic, and the displacement is determined.
01:30Oscillations In An LC Circuit
An idealized LC circuit of zero resistance can oscillate without any source of emf by shifting the energy stored in the circuit between the electric and magnetic fields. In such an LC circuit, if the capacitor contains a charge q before the switch is closed, then all the energy of the circuit is initially stored in the electric field of the capacitor. This energy is given by
01:30Magnetism
Magnets are commonly found in everyday objects, such as toys, hangers, elevators, doorbells, and computer devices. Experimentation on these magnets shows that all magnets have two poles: one is labeled north (N) and the other south (S). Magnetic poles repel if they are alike and attract if unlike. Moreover, both poles of a magnet attract unmagnetized pieces of iron.
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
01:23Magnetic Field due to Moving Charges
A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field.
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...