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GOES Satellites
    Introduction
    Space Environment Monitor
    Magnetic field
    Magnetometer Data Quality
    Energetic particles
    Energetic Particles data quality
    Energetic Particles Correction Algorithm
    X-Rays
    X-Rays Data Quality
    Acronyms
IMF and SWP
    Introduction
    Bx, By, Bz
    Ion density
    Flow speed
Geomagnetic and Solar Indices
    Introduction
    Kp-index
    Ap-index
    Cp-index
    C9-index
    DST-index
    International Sunspot Number
    Solar Radio Flux
Solar Data
    Introduction
    2800 MHz Solar Flux
    Relative Sunspot Number
    Group Sunspot Numbers
    Standard deviations
    Number of observations
Solar Images
    Introduction
    Solar X-Rays
    Solar H-Alpha
    Radio Heliographs
    Magnetogram
Ionospheric Data
    Introduction
    Vertical Incidence Soundings (Ionograms)
    Ionospheric Vertical Incidence Parameters
Geomagnetic Data
    Introduction
Space Weather Events
    Introduction
    X-ray Event Listings
    X-Rays
    X-rays Data Quality


IMF and SWP Data Description

The interplanetary magnetic field (IMF) is a part of the Sun's magnetic field that is carried into interplanetary space by the solar wind. The interplanetary magnetic field lines are said to be "frozen in" to the solar wind plasma. Because of the Sun's rotation, the IMF, like the solar wind, travels outward in a spiral pattern that is often compared to the pattern of water sprayed from a rotating lawn sprinkler. The IMF originates in regions on the Sun where the magnetic field is "open"--that is, where field lines emerging from one region do not return to a conjugate region but extend virtually indefinitely into space. The direction (polarity, sense) of the field in the Sun's northern hemisphere is opposite that of the field in the southern hemisphere. (The polarities reverse with each solar cycle.)

The IMF is a vector quantity with three directional components, two of which (Bx and By) are oriented parallel to the ecliptic. The third component--Bz--is perpendicular to the ecliptic and is created by waves and other disturbances in the solar wind. When the IMF and geomagnetic field lines are oriented opposite or "antiparallel" to each other, they can "merge" or "reconnect," resulting in the transfer of energy, mass, and momentum from the solar wind flow to magnetosphere The strongest coupling --with the most dramatic magnetospheric effects-- occurs when the Bz component is oriented southward.

The IMF is a weak field, varying in strength near the Earth from 1 to 37 nT, with an average value of ~6 nT.

The database contents

The database contains Interplanetary Magnetic Field (IMF) in Geocentric Solar Magnetospheric (GSM) coordinate system and Solar Wind Plasma (SWP) data from many spacecrafts (mostly IMP-8 since 1973) which have explored over the last three decades. Plasma data include ion density and flow bulk speed.

The collected heliospheric IMF and SWP data sets have been provided by Principal Investigator J.H. King (Director, National Space Science Data Center, request@nssdca.gsfc.nasa.gov ). All parameters have been quality controlled, corrected and, as far as possible, written in a similar format.

The interplanetary field and plasma data were all obtained by spacecraft in geocentric or selenocentric orbit when those spacecraft were outside the Earth's bow shock.

WORD DESCRIPTION

UNITS

Bx, GSE

nT

By, GSM

nT

Bz, GSM

nT

Ion density

Per cm3

Flow speed

Km/s