Solar variability for periods of days to months
The time series of total solar-irradiance determinations from ACRIM on the solar maximum mission satellite of 270 days and from the ERB experiment on NIMBUS 7 of 1445 days are analyzed for periods greater than a few days. Comparison of the spectra of both with the spectrum of projected sunspot area over the corresponding time periods show high coherence for periods of 7 to about 25 days and for periods longer than about 30 to 35 days. In the vicinity and at the 27-day rotational period of the sun, however, the coherence between sunspot area and irradiance is small, although both spectra show significant power at and around this period. This means that there is a signal in the irradiance which cannot be due to the sunspot area and the assumption of a straight-forward sunspot blocking seems to be over simplified. This irradiance signal at 27 days has an amplitude of about + or - 0.012 per cent and is an enhancement. 9 references.
- Research Organization:
- Physikalisch-Meteorologisches Observatorium, Davos Dorf, Switzerland
- OSTI ID:
- 5477055
- Report Number(s):
- CONF-8406167-
- Journal Information:
- Adv. Space Res.; (United States), Vol. 4; Conference: 25. plenary session of COSPAR, Graz, Austria, 25 Jun 1984
- Country of Publication:
- United States
- Language:
- English
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