scholarly journals How Does the Sun’s Spectrum Vary?

2012 ◽  
Vol 25 (7) ◽  
pp. 2555-2560 ◽  
Author(s):  
Judith L. Lean ◽  
Matthew T. DeLand
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Solar Spectrum ◽  
Total Solar Irradiance ◽  
Spectral Irradiance ◽  
Model Calculations ◽  
Uv Irradiance ◽  
Infrared Spectral ◽  
Total Irradiance ◽  
Solar Ultraviolet

Abstract Recent observations made by the Spectral Irradiance Monitor (SIM) on the Solar Radiation and Climate Experiment (SORCE) spacecraft suggest that the Sun’s visible and infrared spectral irradiance increased from 2004 to 2008, even as the total solar irradiance measured simultaneously by SORCE’s Total Irradiance Monitor (TIM) decreased. At the same time, solar ultraviolet (UV) irradiance decreased 3–10 times more than expected from prior observations and model calculations of the known effects of sunspot and facular solar features. Analysis of the SIM spectral irradiance observations during the solar minimum epoch of 2008, when solar activity was essentially invariant, exposes trends in the SIM observations relative to both total solar irradiance and solar activity that are unlikely to be solar in origin. The authors suggest that the SIM’s radically different solar variability characterization is a consequence of undetected instrument sensitivity drifts, not true solar spectrum changes. It is thus doubtful that simulations of climate and atmospheric change using SIM measurements are indicative of real terrestrial behavior.

GOES High cadence Operational Total Irradiance: planned data products

2021 ◽  
Author(s):  
Martin Snow ◽  
Stephane Beland ◽  
Odele Coddington ◽  
Steven Penton ◽  
Don Woodraska
Keyword(s):  
Extreme Ultraviolet ◽  
Solar Spectrum ◽  
Total Solar Irradiance ◽  
The Other ◽  
Spectral Irradiance ◽  
First Year ◽  
X Ray ◽  
Solar Spectral Irradiance ◽  
Total Irradiance ◽  
High Cadence

<p>The GOES-R series of satellites includes a redesigned instrument for solar spectral irradiance: the Extreme ultraviolet and X-ray Irradiance Sensor (EXIS).  Our team will be using a high-cadence broadband visible light diode to construct a proxy for Total Solar Irradiance (TSI).  This will have two advantages over the existing TSI measurements:  measurements are taken at 4 Hz, so the cadence of our TSI proxy is likely faster than any existing applications, and the observations are taken from geostationary orbit, so the time series of measurements is virtually uninterrupted.  Calibration of the diode measurements will still rely on the standard TSI composites.  </p><p>The other measurement from EXIS that will be used is the Magnesium II core-to-wing ratio.  The MgII index is a proxy for chromospheric activity, and is measured by EXIS every 3 seconds.  The combination of the two proxies can be used to generate a model of the full solar spectrum similar to the NRLSSI2 empirical model.</p><p>We are in the first year of a three-year grant to develop the TSI proxy and the SSI model, so only very preliminary findings will be discussed in this presentation.</p>

Extending the TSIS-1 Hybrid Solar Reference Spectrum (HSRS) to Span 0.202 to 200 um

2021 ◽  
Author(s):  
Odele Coddington ◽  
Erik Richard ◽  
Dave Harber ◽  
Peter Pilewskie ◽  
Tom Woods ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Solar Irradiance ◽  
Solar Spectrum ◽  
Total Solar Irradiance ◽  
Spectral Irradiance ◽  
High Spectral Resolution ◽  
Reference Spectrum ◽  
Solar Cycles ◽  
Theoretical Understanding ◽  
High Resolution Data

<p>Recently, we incorporated our new understanding of the absolute scale of the solar spectrum as measured by the Spectral Irradiance Monitor (SIM) on the Total and Spectral Solar Irradiance Sensor (TSIS-1) mission and the Compact SIM (CSIM) flight demonstration into a solar irradiance reference spectrum representing solar minimum conditions between solar cycles 24 and 25. This new reference spectrum, called the TSIS-1 Hybrid Solar Reference Spectrum (HSRS), is developed by re-normalizing independent, very high spectral resolution datasets to the TSIS-1 SIM absolute irradiance scale. The high-resolution data are from the Airforce Geophysical Laboratory (AFGL), the Quality Assurance of Ultraviolet Measurements In Europe (QASUME) campaign, the Kitt Peak National Observatory (KPNO) and the Jet Propulsion Laboratory’s (JPL) Solar Pseudo-Transmittance Spectrum (SPTS). The TSIS-1 HSRS spans 0.202 µm to 2.73 µm and has a spectral resolution of 0.01 nm or better. Uncertainties are 0.3% between 0.4 and 2.365 mm and 1.3% at wavelengths outside that range</p><p>Recently, we have extended the long wavelength limit of the TSIS-1 HSRS from 2.73 µm to 200 µm with JPL SPTS solar line data through ~ 16 µm and theoretical understanding as represented in a computed solar irradiance spectrum by R. Kurucz. The extension expands the utility of this new solar irradiance reference spectrum to include Earth energy budget studies because it encompasses an integrated energy in excess of 99.99% of the total solar irradiance.</p><p>In this work, we discuss the TSIS-1 HSRS, the extension and uncertainties, and demonstrate consistency with TSIS-1 SIM and CSIM solar spectral irradiance observations and TSIS-1 Total Irradiance Monitor (TIM) total solar irradiance observations. Additionally, we compare the TSIS-1 HSRS against independent measured and modeled solar reference spectra.</p>

Solar spectral irradiance and total solar irradiance at a solar minimum

2014 ◽  
Vol 54 (7) ◽  
pp. 926-932 ◽  
Author(s):  
E. E. Benevolenskaya ◽  
S. N. Shapovalov ◽  
I. G. Kostuchenko
Keyword(s):  
Solar Irradiance ◽  
Solar Minimum ◽  
Total Solar Irradiance ◽  
Spectral Irradiance ◽  
Solar Spectral Irradiance

scholarly journals A reconstruction of radiocarbon production and total solar irradiance from the Holocene <sup>14</sup>C and CO<sub>2</sub> records: implications of data and model uncertainties

2013 ◽  
Vol 9 (4) ◽  
pp. 1879-1909 ◽  
Author(s):  
R. Roth ◽  
F. Joos
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Surface Air Temperature ◽  
Total Solar Irradiance ◽  
Production Model ◽  
High Solar Activity ◽  
Solar Modulation ◽  
Time Lags ◽  
Instrumental Data ◽  
The Holocene

Abstract. Radiocarbon production, solar activity, total solar irradiance (TSI) and solar-induced climate change are reconstructed for the Holocene (10 to 0 kyr BP), and TSI is predicted for the next centuries. The IntCal09/SHCal04 radiocarbon and ice core CO2 records, reconstructions of the geomagnetic dipole, and instrumental data of solar activity are applied in the Bern3D-LPJ, a fully featured Earth system model of intermediate complexity including a 3-D dynamic ocean, ocean sediments, and a dynamic vegetation model, and in formulations linking radiocarbon production, the solar modulation potential, and TSI. Uncertainties are assessed using Monte Carlo simulations and bounding scenarios. Transient climate simulations span the past 21 thousand years, thereby considering the time lags and uncertainties associated with the last glacial termination. Our carbon-cycle-based modern estimate of radiocarbon production of 1.7 atoms cm−2 s−1 is lower than previously reported for the cosmogenic nuclide production model by Masarik and Beer (2009) and is more in-line with Kovaltsov et al. (2012). In contrast to earlier studies, periods of high solar activity were quite common not only in recent millennia, but throughout the Holocene. Notable deviations compared to earlier reconstructions are also found on decadal to centennial timescales. We show that earlier Holocene reconstructions, not accounting for the interhemispheric gradients in radiocarbon, are biased low. Solar activity is during 28% of the time higher than the modern average (650 MeV), but the absolute values remain weakly constrained due to uncertainties in the normalisation of the solar modulation to instrumental data. A recently published solar activity–TSI relationship yields small changes in Holocene TSI of the order of 1 W m−2 with a Maunder Minimum irradiance reduction of 0.85 ± 0.16 W m−2. Related solar-induced variations in global mean surface air temperature are simulated to be within 0.1 K. Autoregressive modelling suggests a declining trend of solar activity in the 21st century towards average Holocene conditions.

scholarly journals Irradiance Observations from the UARS/SUSIM and ATLAS/SUSIM Experiments

1994 ◽  
Vol 143 ◽  
pp. 72-72 ◽  
Author(s):  
Guenter Brueckner ◽  
Linton E. Floyd ◽  
Paul A. Lund ◽  
Dianne K. Prinz ◽  
Michael E. Vanhoosier
Keyword(s):  
Solar Spectrum ◽  
Daily Basis ◽  
Spectral Irradiance ◽  
Reference Channel ◽  
Term Stability ◽  
Long Term Stability ◽  
Solar Uv ◽  
Solar Ultraviolet ◽  
Better Than

The SUSIM (Solar Ultraviolet Spectral Irradiance Monitor) on board the UARS (Upper Atmosphere Research Satellite) has measured the solar UV output from 120 nm to 400 nm on a daily basis since October 1991. A reference channel records a solar spectrum semi-annually only to reduce the instrument degradation of this channel and to provide long-term stability marks. Four deuterium lamps are used at monthly, semi-annual and annual intervals to provide long term calibration of the instrument. A preliminary analysis of the long term stability of SUSIM-UARS indicates that the precision of the instrument should be better than a few percent. The repeatability of two scans is better than 0.2%. A simplified SUSIM instrument is flying on NASA’s ATLAS Spacelab missions anually to provide calibration points for the SUSIM-UARS.

scholarly journals The Total Solar Irradiance, UV Emission and Magnetic Flux during the Last Solar Cycle Minimum

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
E. E. Benevolenskaya ◽  
I. G. Kostuchenko
Keyword(s):  
Solar Activity ◽  
Magnetic Flux ◽  
Solar Irradiance ◽  
Solar Minimum ◽  
Total Solar Irradiance ◽  
Sunspot Activity ◽  
Ultraviolet Emission ◽  
Uv Emission ◽  
Surface Rotation ◽  
Spectral Solar Irradiance

We have analyzed the total solar irradiance (TSI) and the spectral solar irradiance as ultraviolet emission (UV) in the wavelength range 115–180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (the solar radiation and climate experiment) during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on the surface rotation timescales of solar activity complexes. In-phase coherent structures between the midlatitude magnetic flux and TSI/UV appear when the long-lived complexes of the solar activity are present. These complexes, which are related to long-lived sources of magnetic fields under the photosphere, are maintained by magnetic fluxes reappearing in the same longitudinal regions. During the deep solar minimum (the period of the absence of sunspots), a coherent structure has been found, in which the phase between the integrated midlatitude magnetic flux is ahead of the total solar irradiance on the timescales of the surface rotation.

The Signature of Solar Activity in the Infrared Spectral Irradiance

2004 ◽  
Vol 605 (1) ◽  
pp. L85-L88 ◽  
Author(s):  
J. M. Fontenla ◽  
J. Harder ◽  
G. Rottman ◽  
T. N. Woods ◽  
G. M. Lawrence ◽  
...  
Keyword(s):  
Solar Activity ◽  
Spectral Irradiance ◽  
Infrared Spectral
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