Why is the Solar Constant Not a Constant?
Abstract
In order to probe the mechanism of variations of the solar constant on the inter-solar-cycle scale, the total solar irradiance (TSI; the so-called solar constant) in the time interval of 1978 November 7 to 2010 September 20 is decomposed into three components through empirical mode decomposition and time-frequency analyses. The first component is the rotation signal, counting up to 42.31% of the total variation of TSI, which is understood to be mainly caused by large magnetic structures, including sunspot groups. The second is an annual-variation signal, counting up to 15.17% of the total variation, the origin of which is not known at this point in time. Finally, the third is the inter-solar-cycle signal, counting up to 42.52%, which is inferred to be caused by the network magnetic elements in quiet regions, whose magnetic flux ranges from (4.27-38.01) × 1019 Mx.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2012
- DOI:
- 10.1088/0004-637X/747/2/135
- arXiv:
- arXiv:1201.0819
- Bibcode:
- 2012ApJ...747..135L
- Keywords:
-
- Sun: activity;
- Sun: general;
- sunspots;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- to appear in ApJ