Total solar irradiance since 1996: is there a long-term variation unrelated to solar surface magnetic phenomena?

<p>The uninterrupted, 41-year-long, spaceborne total solar irradiance (TSI) record has recently undergone several changes in the instruments contributing to these measurements of the net incoming radiant energy providing nearly all the power driving the Earth&#8217;s climate system. Two long-term instruments, NASA&#8217;s SORCE/TIM and TCTE/TIM, have recently been powered off. This ends the 17-year record from the SORCE/TIM, which established the currently-accepted TSI value of 1361 W&#160;m<sup>&#8209;2</sup> after its launch in 2003. ESA&#8217;s SoHO/VIRGO continues to acquire measurements that extend its 24-year record, but data availability has been on hold as a new processing methodology is implemented. NASA&#8217;s recently-launched TSIS&#8209;1/TIM is presently continuing the measurements of these stalwart legacy instruments. This new TSI instrument is demonstrating higher on-orbit accuracy than any prior such instrument has achieved, with daily measurement updates that are available to the community for climate- and solar-research purposes. I will discuss the many recent changes to the spaceborne TSI measurement record, the current measurement-accuracy improvements and stabilities achieved and their implications for Earth energy-balance studies, and the future plans to maintain measurement continuity.</p>

Download Full-text

Evidence of a long-term trend in total solar irradiance

Astronomy and Astrophysics ◽

10.1051/0004-6361/200912318 ◽

2009 ◽

Vol 501 (3) ◽

pp. L27-L30 ◽

Cited By ~ 157

Author(s):

C. Fröhlich

Keyword(s):

Solar Irradiance ◽

Total Solar Irradiance ◽

Term Trend ◽

Long Term Trend

Download Full-text

Long-term total solar irradiance variability during sunspot cycle 22

Journal of Geophysical Research Atmospheres ◽

10.1029/94ja02897 ◽

1995 ◽

Vol 100 (A2) ◽

pp. 1667 ◽

Cited By ~ 91

Author(s):

Robert B. Lee ◽

M. Alan Gibson ◽

Robert S. Wilson ◽

Susan Thomas

Keyword(s):

Solar Irradiance ◽

Sunspot Cycle ◽

Total Solar Irradiance

Download Full-text

Modeling Quiet Solar Luminosity Variability from TSI Satellite Measurements and Proxy Models during 1980–2018

Remote Sensing ◽

10.3390/rs11212569 ◽

2019 ◽

Vol 11 (21) ◽

pp. 2569 ◽

Cited By ~ 5

Author(s):

Nicola Scafetta ◽

Richard Willson ◽

Jae Lee ◽

Dong Wu

Keyword(s):

Solar Irradiance ◽

Total Solar Irradiance ◽

Main Question ◽

Satellite Measurements ◽

Significant Discrepancy ◽

Solar Luminosity ◽

Continuous Record ◽

Before And After ◽

Proxy Models

A continuous record of direct total solar irradiance (TSI) observations began with a series of satellite experiments in 1978. This record requires comparisons of overlapping satellite observations with adequate relative precisions to provide useful long term TSI trend information. Herein we briefly review the active cavity radiometer irradiance monitor physikalisch-meteorologisches observatorium davos (ACRIM-PMOD) TSI composite controversy regarding how the total solar irradiance (TSI) has evolved since 1978 and about whether TSI significantly increased or slightly decreased from 1980 to 2000. The main question is whether TSI increased or decreased during the so-called ACRIM-gap period from 1989 to 1992. There is significant discrepancy between TSI proxy models and observations before and after the gap, which requires a careful revisit of the data analysis and modeling performed during the ACRIM-gap period. In this study, we use three recently proposed TSI proxy models that do not present any TSI increase during the ACRIM-gap, and show that they agree with the TSI data only from 1996 to 2016. However, these same models significantly diverge from the observations from 1981 and 1996. Thus, the scaling errors must be different between the two periods, which suggests errors in these models. By adjusting the TSI proxy models to agree with the data patterns before and after the ACRIM-gap, we found that these models miss a slowly varying TSI component. The adjusted models suggest that the quiet solar luminosity increased from the 1986 to the 1996 TSI minimum by about 0.45 W/m2 reaching a peak near 2000 and decreased by about 0.15 W/m2 from the 1996 to the 2008 TSI cycle minimum. This pattern is found to be compatible with the ACRIM TSI composite and confirms the ACRIM TSI increasing trend from 1980 to 2000, followed by a long-term decreasing trend since.

Download Full-text

Properties of Flux Tubes and the Relation with Solar Irradiance Variability

International Astronomical Union Colloquium ◽

10.1017/s0252921100064678 ◽

2000 ◽

Vol 179 ◽

pp. 275-282

Author(s):

M. Fligge ◽

S. K. Solanki

Keyword(s):

Spatial Resolution ◽

Solar Irradiance ◽

Solar Surface ◽

Surface Flux ◽

Small Scale ◽

Discrete Elements ◽

Flux Tubes ◽

Magnetic Flux Tubes ◽

The Magnetic Field

AbstractAt the solar surface the magnetic field is bundled into discrete elements of concentrated flux, often referred to as magnetic flux tubes, which cover only a small fraction of the solar surface. Flux tubes span a whole spectrum of sizes, ranging from sunspots to features well below the best currently obtainable spatial resolution.Whereas sunspots have been well studied, our knowledge of the true brightness of small-scale magnetic features is hampered by the insufficient spatial resolution of the observations. A better understanding of the thermal and magnetic properties of these small-scale features, however, is crucial for an understanding of (climate-relevant) long-term solar irradiance variations.

Download Full-text