Solar activity and heliosphere-wide cosmic ray modulation in mid-1982

Journal Article · Sat Aug 01 04:00:00 EDT 1987 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA092iA08p08487· OSTI ID:6210337

Cliver, E W; Mihalov, J D; Sheeley, Jr, N R; Howard, R A; Koomen, M J; Schwenn, R

A major episode of flare activity in June and July 1982 was accompaniedby a pair of heliosphere-wide cosmic ray modulation events. In each case, a large Forbush decrease (FD) at earth was followed in turn by apparently related decreases at Pioneer 11 (P11) and Pioneer 10 (P10). The Pioneer spacecraft were separated by --155/sup 0/ in ecliptic longitude. We reviewed white light coronagraph and near-sun (less than or equal to1 AU) satellite data to identify plausible solar origins of these modulation events. The first widespread intensity decrease (FD 1) can be attributed to the combined effects of a backside flare on June 3 from solar active region 18382/18383, located 23/sup 0/ in ecliptic longitude from Pioneer 10, and a visible disk flare from 18405 on June 6, when this region was 9/sup 0/ from Pioneer 11. The second widespread modulation event during this period (FD 2) may be linked to flares from active region 18474 on July 12 and 22. The July 12 flare was located 34/sup 0/ in azimuth from Pioneer 11, and the July 22 flare was 24/sup 0/ from Pioneer 10. Since even fast shocks would take --1 month to propagate to Pioneer 11 (12 AU) and --2 months to reach Pioneer 10 (28 AU) in mid-1982, these ''one-to-one'' associations must be regarded with caution. The processes of entrainment and coalescence can cause a given traveling interplanetary disturbance to lose its identify enroute to the outer heliosphere. The fact that we were able to identify plausible solar flare candidates for each of the four Forbushlike decreases observed at the Pioneer satellites (two each at P10 and P11), however, removes the need to invoke a chock from a single flare as the sole cause of either FD 1 (at both P10 and P11) or FD 2.

• Research Organization: Air Force Geophysics Laboratory, Hanscom Air Force Base, Bedford, Massachusetts
• OSTI ID: 6210337
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 92:A8; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIATION
DATA ANALYSIS
FORBUSH DECREASE
IONIZING RADIATIONS
MODULATION
PIONEER SPACE PROBES
RADIATIONS
SHOCK WAVES
SOLAR ACTIVITY
SOLAR FLARES
SOLAR WIND
SPACE VEHICLES
VEHICLES