Solar-cycle variations of coronal neutral lines and polar regions activity

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5763213

Makarov, V I; Makarova, V V; Koutchmy, S; Sivaraman, K R

Observations of the corona, of prominences, of polar faculae and of large scale magnetic fields show solar activity over all latitudes, in contrast with sunspot activity, which is limited to mid-latitudes. The global behavior of the solar activity is considered here thanks to the analysis of chromospheric synoptic maps which include the location of H/alpha/ and Ca II k prominences. The process of migration of neutral lines during the cycle (supposed to represent the large-scale coronal magnetic field) is shown. After subsequent averaging of the maps, a discrete number of latitude zones is found: not more than 10, the most probable number being 3 or 5. This suggests the occurrence of dominant modes (1=3 and 1=5) of the large-scale coronal magnetic field and inferred coronal structures for different epochs of the solar cycle. The geoactivity of coronal streamers could be related to the modes, noticing the dipole (1=1) mode is almost absent. A more-detailed analysis points to the importance of the poleward migration of neutral lines (with v = 5 to 40 micro sec-1). The nonsymmetric behavior of the N and S hemisphere as well as the erratic behavior of the corresponding sunspot activity in each hemisphere is emphasized, which reflects the behavior of both the radial component and the toroidal component of the field.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5763213
• Report Number(s): AD-A-205765/1/XAB; AFGL-TR-89-0059
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHROMOSPHERE
FACULAE
MAGNETIC FIELDS
MAPPING
PROBABILITY
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR CYCLE
SOLAR PROMINENCES
STARSPOTS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
SUNSPOTS