Solar cycle variations in the interplanetary magnetic field

Technical Report · Tue Nov 01 04:00:00 EST 1983

OSTI ID:6530817

Slavin, J A; Smith, E J

ISEE 3 interplanetary magnetic field measurements have been used to extend the NSSDC hourly averaged IMF composite data set through mid-1982. Most of sunspot cycle 20 (start:1964) and the first half of cycle 21 (start:1976) are now covered. The average magnitude of the field was relatively constant over cycle 20 with approx. 5-10% decreases in 1969 and 1971, when the Sun's polar regions changed polarity, and a 20% decrease in 1975-6 around solar minimum. Since the start of the new cycle, the total field strength has risen with the mean for the first third of 1982 being about 40% greater than the cycle 20 average. As during the previous cycle, an approx. 10% drop in IMF magnitude accompanied the 1980 reversal of the solar magnetic field. While the interplanetary magnetic field is clearly stronger during the present solar cycle, another 5-7 years of observations will be needed to determine if cycle 21 exhibits the same modest variations as the last cycle. Accordingly, it appears at this time that intercycle changes in IMF magnitude may be much larger than the intracycle variations.

• Research Organization: Jet Propulsion Lab., Pasadena, CA (USA)
• OSTI ID: 6530817
• Report Number(s): N-84-13091
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ERRORS
INTERPLANETARY MAGNETIC FIELDS
MAGNETIC FIELDS
MAGNETIC FLUX
POLAR REGIONS
SOLAR ACTIVITY
SOLAR CYCLE
SOLAR WIND
STARSPOTS
SUNSPOTS
TURBULENCE
VARIATIONS