Observations of field-aligned currents, waves, and electric fields at substorm onset

Journal Article · Wed Jan 01 04:00:00 EST 1986 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA091iA01p00121· OSTI ID:6328219

Smits, D P; Hughes, W J; Cattell, C A; Russell, C T

Substorm onsets, identified by Pi 2 pulsations observed on the Air Force Geophysics Laboratory Magnetometer Network, are studied using magnetometer and electric field data from ISEE 1 as well as magnetometer data from the geosynchronous satellites GOES 2 and 3. The mid-latitude magnetometer data provides the means of both timing and locating the substorm onset so that the spacecraft locations with respect to the substorm current systems are known. During two intervals, each containing several onsets or intensifications, ISEE 1 observed field-aligned current signatures beginning simultaneously with the mid-latitude Pi 2 pulsation. Close to the earth broadband bursts of wave noise were observed in the electric field data whenever field-aligned currents were detected. One onset occurred when ISEE 1 and GOES 2 were on the same field line but in opposite hemispheres. During this onset ISEE 1 and GOES 2 saw magnetic signatures which appear to be due to conjugate field-aligned currents flowing out of the western end of the westward auroral electrojets. The ISEE 1 signature is of a line current moving westward past the spacecraft. During the other interval, ISEE 1 was in the near-tail region near the midnight meridian. Plasma data confirms that the plasma sheet thinned and subsequently expanded at onset. Electric field data shows that the plasma moved in the opposite direction to the plasma sheet boundary as the boundary expanded which implies that there must have been an abundant source of hot plasma present. The plasma motion was towards the center of the plasma sheet and earthwards and consisted of a series of pulses rather than a steady flow.

• Research Organization: Astronomy Department, Boston University, Boston, Massachusetts
• OSTI ID: 6328219
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 91:A1; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CURRENTS
DATA ANALYSIS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTRIC MEASURING INSTRUMENTS
ELECTRICAL EQUIPMENT
ELECTROJETS
EQUIPMENT
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC STORMS
MAGNETOMETERS
MEASURING INSTRUMENTS
PLASMA
PLASMA SHEET
SATELLITES