Investigation of short period oscillations of the solar irradiance and their time variations. Final technical report, 15 February 1985-14 December 1986

Technical Report · Sat Aug 01 00:00:00 EDT 1987

OSTI ID:5886190

Noyes, R W

Measurements of solar irradiance fluctuations by the Active Cavity Radiometer (ACRIM) instrument onboard the Solar Maximum Mission (SMM) show variations on a time scale of about 5 minutes due to solar p-mode oscillations, as well as longer-term variations related to solar magnetic activity. The question was studied whether the p-mode frequencies change with time as a result of changing solar structure associated with the activity cycle. The ACRIM data on SMM are particularly well-suited for this purpose, because the instrument operated continuously from February 1980 to December 1980 and again from May 1984 to the present. The main activity entailed a detailed study of the observational data to determine if a change in the p-mode frequencies is evident from the time of solar maximum to that of solar minimum. It was concluded that the measured eigenfrequencies were significantly higher during the 1980 time frame than during the 1984 to 1986 time frame. The conclusion that there is significant change in the eigenfrequencies with the activity cycle remains only tentative, and needs confirmation from analysis of more data during the upcoming solar maximum.

• Research Organization: Smithsonian Astrophysical Observatory, Cambridge, MA (USA)
• OSTI ID: 5886190
• Report Number(s): N-87-27585; NASA-CR-180340; NAS-1.26:180340
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DATA
DATA PROCESSING
EXPERIMENTAL DATA
INFORMATION
MEASURING INSTRUMENTS
NUMERICAL DATA
OSCILLATIONS
P WAVES
PARTIAL WAVES
PROCESSING
RADIATION DETECTORS
RADIATIONS
RADIOMETERS
SOLAR ACTIVITY
SOLAR RADIATION
STARSPOTS
STELLAR ACTIVITY
STELLAR RADIATION
SUNSPOTS
VARIATIONS
WAVE PROPAGATION