J. Space Weather Space Clim.
Volume 6, 2016
Brightness Variations of the Sun and Sun-like Stars and Resulting Influences on their Environments
|Number of page(s)||13|
|Published online||05 September 2016|
Solar rotational modulations of spectral irradiance and correlations with the variability of total solar irradiance
Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD, USA
2 NASA Goddard Space Flight Center, Greenbelt, MD, USA
* Corresponding author: email@example.com
Accepted: 15 August 2016
Aims: We characterize the solar rotational modulations of spectral solar irradiance (SSI) and compare them with the corresponding changes of total solar irradiance (TSI). Solar rotational modulations of TSI and SSI at wavelengths between 120 and 1600 nm are identified over one hundred Carrington rotational cycles during 2003–2013.
Methods: The SORCE (Solar Radiation and Climate Experiment) and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SEE (Solar EUV Experiment) measured and SATIRE-S modeled solar irradiances are analyzed using the EEMD (Ensemble Empirical Mode Decomposition) method to determine the phase and amplitude of 27-day solar rotational variation in TSI and SSI.
Results: The mode decomposition clearly identifies 27-day solar rotational variations in SSI between 120 and 1600 nm, and there is a robust wavelength dependence in the phase of the rotational mode relative to that of TSI. The rotational modes of visible (VIS) and near infrared (NIR) are in phase with the mode of TSI, but the phase of the rotational mode of ultraviolet (UV) exhibits differences from that of TSI. While it is questionable that the VIS to NIR portion of the solar spectrum has yet been observed with sufficient accuracy and precision to determine the 11-year solar cycle variations, the temporal variations over one hundred cycles of 27-day solar rotation, independent of the two solar cycles in which they are embedded, show distinct solar rotational modulations at each wavelength.
Key words: Solar rotational modulation / Total solar irradiance / Spectral solar irradiance / SORCE / SATIRE-S
© J.N. Lee et al., Published by EDP Sciences 2016
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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