SH43A-1503
Reconstruction of the Past Solar Spectra (1) Deduced Solar Spectra of Sunspots, Faculae and Quiet Regions
We don�ft have direct measurement of the past solar spectral irradiance before achievement of its measurement from the space. The SORCE satellite (Rottman, et al., 2005), which was launched in 2003, is monitoring solar spectra from UV to IR wavelengths. It makes possible to know daily solar spectral irradiance variations due to various features on the solar surface, and this kind of observations are useful for the earth�fs atmospheric model to yield progress in understanding a connection between the sun and global climate change. Some studies (e.g., Unruh, et al., 2000) adopted three components (sunspot, facular, and quiet region) for modeling solar irradiance variations. Here, we also regarded these components as solar features for spectral irradiance variations. Firstly, we tried to estimate average spectrum of these three components respectively from the SORCE data as accurate as possible. Additionally, we used Ca K image data taken by the Big Bear Solar Observatory in order to find counterparts of solar spectral variations in the solar features. One of the reasons why we used Ca K data is that there are abundant historical data of Ca K observation nearly 90 years long. Also, it might make it easy to analogize the relationship between solar and stellar chromospheric variability and let it introduce to long term solar spectral variations. These advantages will be related to the further studies. In this study, we focused on July 2004. This period is characterized by the minimum of total solar irradiance through the year 2004. We defined certain thresholds from intensity distribution of a Ca K image and then estimated sunspot and facular areas. For this analysis, we used only good quality SORCE data without any discontinuity in spectrum. Finally, considering that there is a one-to-one correspondence between surface coverage rates of three components and spectral variations, we carried out a regression analysis and obtained solar spectra of sunspot, facular and quiet region respectively.
SH43A-1504
Correlations Between Total Solar Irradiance and Spectral Irradiances Using SORCE Measurements
The SOlar Radiation and Climate Experiment (SORCE) was launched in January 2003 to measure both total solar irradiance (TSI) and spectral solar irradiance (SSI). The available spectral irradiances are contiguous from 115 nm to 1600 nm with nearly daily coverage, providing useful inputs to climate models since the Earth's atmospheric response is highly wavelength dependent. By correlating these relatively recent and short-duration spectral irradiances with simultaneous SORCE TSI measurements, the SSI may be linked to the nearly 3-decade long TSI record. Extending this SSI proxy via the TSI record may provide an estimate of historical spectral irradiances allowing comparisons to past climate. I present results from these wavelength-dependent correlations between SORCE TSI and SSI measurements.
http://lasp.colorado.edu/sorce/
SH43A-1505
Total Solar Irradiance Trends During Solar Cycles 21-24
Total solar irradiance (TSI) observations have been made by contiguous, redundant, overlapping satellite experiments since 1978 during solar activity cycles 21 - 23. The solar activity minimum marking the inception of cycle 24 is imminent - some sunspot magnetic polarity reversals have already been detected. The ACRIM TSI composite time series found a 0.04 percent per decade trend between the minima of cycles 21 to 23. A trend of this magnitude, sustained over many decades or centuries, could be a significant climate forcing. Great interest will be attached to the behavior of the TSI time series during the upcoming and future solar activity minima with respect to the presence or absence of a trend. An updated TSI composite will be presented to examine the trend at or near the minima between solar cycles 23 and 24.
http://www.acrim.com
SH43A-1506
Hot Young Solution to Faint Sun Paradox
The "Faint Young Sun" has been a paradox of astrophysics. The standard solar model predicts that 4 billion years ago Earth was too cold to support life. Geology and the fossil record contradict this prediction. The paradox and possible solution are a fascinating combination of astrophysics, relativity and the Earth sciences. Models predict that 4 billion years ago the Sun shone with only 70 % of its present luminosity. Since power P is related to temperature T by the Stefan-Boltzmann Law P \propto T$^{4}$, Earth temperature would have been only 91 % of its present value. That temperature is approximately 283K, so temperature in the past would have been only 258K. Earth's surface would have frozen solid, making evolution of life very unlikely. Geology shows evidence of extensive sedimentation 4 billion years ago. Other geological markers corroborate the presence of liquid water on Earth during this period. Paleontology dates the earliest organisms at least 3.4 to 4 billion years old. Clearly liquid water and life both existed when the model predicts Earth was frozen solid. This conflict with observations is the Faint Young Sun paradox. Fortunately, Relativity and Space/Time can help save the standard solar model. The Sun converts its fuel to energy according to E=mc$^{2}$. Unified Space/Time predicts that c is given by: GM=tc$^{3}$. Where t is age of the Universe, GM combines its mass and gravitational constant. Solving, we have c(t)=(GM)$^{1/3}$ t$^{-1/3}$. Billions of years ago, solar output and temperature were therefore higher than originally calculated. Earth is estimated to be 4.6 billion years and the Universe 13.7 billion years old, 1.5 times its age at the time of Earth's formation. Energy e=mc$^{2}$ is adjusted by (1.5)$^{2/3}$ = 1.31 times the initial estimate. Multiplying by that estimate of 70 %, the Sun's actual output was 0.917 of the present value. Temperature was then (0.917)$^{1/4}$ = 98 % of today's value. If we start with an estimate of 76 %, the Sun's true output was exactly the present value. The �paradox� leads to an extraordinary confirmation of Theory. The solar constant may indeed be constant, allowing life to have evolved on Earth for billions of years. Prediction of a changing c can be more precisely corroborated using observations of Type Ia supernovae. Earth's temperature provides additional data points to supplement supernova data from a more distant past. This corroborating data distinguishes Theory from �accelerating universe� ideas. Theory also may help determine whether CO2 warmed Earth's temperature in the past. In conclusion, the �Faint Young Sun� is not a problem but a window from the Earth sciences to astrophysics and cosmology. Geology and the fossil record can help verify �fossil� values of fundamental measurements, determining whether those values are indeed constant.
SH43A-1507
Statistical properties of H-alpha and HXR flares in the cycle 23 in relation to sunspots and active regions detected from the Solar Feature Catalogues
The statistical properties of H-alpha and hard X-ray solar flares are investigated in relation to the cycle variations in 1996-2006 of sunspots and active regions (plages) obtained from the automated Soar Feature Catalogues (SFC, http://solar.inf.brad.ac.uk). Cross-correlation analysis is carried out between flare sizes, locations, significance and active region/sunspot parameters including magnetic field extracted in SFC. Sunspot and plage area distributions reveals a strong North-South asymmetry of about 0.2 and the period of about 7-8 years for sunspots and of 0.5 and period of 9 years for plages with both asymmetries decreasing towards the next cycle minimum. The temporal distribution of solar flare occurrences in Northern and Southern hemispheres, at different latitudes and longitudes are compared with those of plage and sunspot areas and LOS magnetic fields. The spectral indices of HXR and gamma-ray emission wer used to estimate magnetic field components and their variations with the cycle. The application of these results to the solar activity forecast is discussed.
SH43A-1508
Evolution of Sunspots and Their Effect on Solar Irradiance Variations
The goal of this paper is to examine the evolution of sunspots and their relation to solar irradiance variations based on the sunspot data archive of the Heliophysical Observatory of the Hungarian Academy of Sciences. Long-term full-disk white-light observations have been made at the Debrecen Heliophysical Observatory and its Gyula observing station. Using observations from other observatories when they are not availabe in this archive is being used to complete a sunspot catalogue as a continuation of the Greenwich Catalogue and to provide a homogeneuous data base of the area and position of sunspots covering a century long time interval. As part of the measurement process, the photoheliograms are digitized and resolved into a 8K$\times$8K matrix, which allows to measure and catalogue the area and position of sunspots (both umbra and penumbra) with high accuracy. These sunspot data are published in the Debrecen Photoheliographic Data catalogue (DPD). Since 1996, the SOHO/MDI intensity images have also been processed and analyzed in the same way as the DPD images and these MDI sunspot area and position data are published in the SOHO/MDI -- Debrecen Data (SDD) catalogue. In addition to the MDI intensity images, the MDI magnetograms are used to gather information about the average magnetic field strength values and polarities of the investigated sunspot umbra and penumbra.Considering the availability of the high time cadence MDI observations, we are able to study the evolution of sunspots in detail. In this paper we concentrate on the time frame of 1996 to 1997, when individual sunspot groups can be well-separated and their effect on solar irradiance can be studied in detail.