The Sun's luminosity over a complete solar cycle

  title={The Sun's luminosity over a complete solar cycle},
  author={Richard C. Willson and Hugh S. Hudson},
THE Active Cavity Radiometer Irradiance Monitor (ACRIM I), an instrument carried on NASA's Solar Maximum Mission satellite, measured the Sun's luminosity (total power outflow) from early 1980 to late 19891–5. Here we present the first account of the complete ACRIM I data set, and give evidence confirming our previous suggestion that solar luminosity varies with the 11-year solar cycle6. As previously reported, this slow variation closely follows statistical measures of the distribution of… 

Solar radiative output and its variability: evidence and mechanisms

Abstract.Electromagnetic radiation from the Sun is Earth’s primary energy source. Space-based radiometric measurements in the past two decades have begun to establish the nature, magnitude and

Solar-cycle dependence of the Sun's apparent radius in the neutral iron spectral line at 525 nm

SPACE-BASED observations have established that the Sun's irradiance varies with solar magnetic activityl-4. A fraction of this variability arises from the increased area of cool gas associated with

Variations in total solar irradiance during solar cycle 22

In this study, we have attempted to model the variations in total solar irradiance from two spacecraft. Specifically, we have modeled the Earth Radiation Budget on the Nimbus 7 spacecraft and the

Magnitudes and timescales of total solar irradiance variability

  • G. Kopp
  • Physics, Environmental Science
  • 2016
The Sun’s net radiative output varies on timescales of minutes to gigayears. Direct measurements of the total solar irradiance (TSI) show changes in the spatially- and spectrally-integrated radiant

Solar Forcing of Global Climate Change Since The Mid-17th Century

Spacecraft measurements of the sun's total irradiance since 1980 have revealed a long-term variation that is roughly in phase with the 11-year solar cycle. Its origin is uncertain, but may be related

A technique for estimating long-term variations of solar total irradiance: Preliminary estimates based on observations of the Sun and solar-type stars

We analyze concurrent observations of Ca II H and K chromospheric emission fluxes (which are associated with the disk-averaged surface magnetic fluxes) and variability in the b and y bands of the

Solar Total Irradiance: A Reference Value for Solar Minimum

Simultaneous solar total irradiance observations performed by absolute radiometers on board satellites during the quiet-Sun period between solar cycles 21 and 22 (1985–1987), are analyzed to

Long-term solar brightness changes estimated from a survey of Sun-like stars

THE brightness of the Sun varies during the 11-year solar cycle, typically by less than 0.1% (refs 1, 2), and a larger brightness variation is thought to have occurred during the Maunder minimum,

A discussion of plausible solar irradiance variations, 1700-1992

From satellite observations the solar total irradiance is known to vary. Sunspot blocking, facular emission, and network emission are three identified causes for the variations. In this paper we

Measurement of Total and Spectral Solar Irradiance

The Sun’s electromagnetic radiation powers our solar system. In the case of the Earth it heats the lands and ocean, maintains our atmosphere, generates clouds, and cycles water. For other planets and



Solar luminosity variations in solar cycle 21

The ACRIM I experiment (Active Cavity Radiometer Irradiance Monitor) on the solar maximum Mission (SMM) satellite has provided a nearly continuous record of solar total irradiance variations since

Solar irradiance variations and solar activity

A mean value for the 1 AU total solar irradiance of 1368.2 W/m/sup 2/ and a downward trend of 0.05% per year were derived from measurements by the Active Cavity Radiometer Irradiance Monitor (ACRIM)

The effects of sunspots on solar irradiance

Sunspots have an obvious direct effect upon the visible radiant energy falling upon the Earth. We show how to estimate this effect and compare it quantitatively with recent observations of the solar

Observations of solar irradiance variability.

Measurements of total solar irradiance show the irradiance to have been variable throughout the first 153 days of observations, and suggest that considerable energy storage occurs within the convection zone in solar active regions.

Total solar irradiance measurements by ERB/Nimbus-7. A review of nine years

The advent of reliable extraterrestrial solar irradiance measurements from satellites has supplied the impetus for new research in solar physics and solar-terrestrial relationships. The records for

Magnetic modulation of solar luminosity by photospheric activity

The behavior of slow changes in solar irradiance S is studied using measurements obtained with radiometers on the SMM and Nimbus 7 spacecraft. The general downtrend in the radiometer readings is

Long-Term Downward Trend in Total Solar Irradiance

The first 5 years of total solar irradiance observations by the first Active Cavity Radiometer Irradiance Monitor (ACRIM I) experiment show a clearly defined downward trend, which appears to be due to unpredicted variations of solar luminosity on time scales of years, and it may be related to solar cycle magnetic activity.

An Empirical Model of Total Solar Irradiance Variation Between 1874 and 1988

The model provides a remarkably good representation of the irradiance variations observed by satellite-borne radiometers between 1980 and 1988, suggesting that the mean total irradiance has been rising steadily since about 1945, with the largest peak so far at about 1980 and another large peak expected during the current solar cycle 22.

An Alternative Derivation of the Nimbus 7 Total Solar Irradiance Variations

Nimbus 7 solar irradiance values have been made available to the scientific community through the open literature (e.g., Hickey et al., 1988) and through NASA data centers. A comparison of these

Spectrum Line Intensity as a Surrogate for Solar Irradiance Variations

Comparisons with ground-based, irradiance spectrophotometry of selected Fraunhofer lines independently confirm the variability in the ACRIM Se, signal, indicate that the source of irradiance is faculae, and indicate that ACRim Se, follows the 11-year activity cycle.