Decadal Cycles in the Sun, Sun-like Stars, and Earth’s Climate System
SORCE Science Meeting
Sedona, Arizona * Sept. 13-16, 2011
Poster Session Abstracts
4:00-5:30 p.m., Wednesday, Sept. 15
Summary of Poster Presentations (in alphabetical order):
Angie Cookson, San Fernando Observatory, California State University, Northridge
Mind the Gap: How well can SFO ground-based photometry construct future missing
TSI measurements?
David Douglass, University of Rochester, New York
Topology of the Earth's Climate Indices and Phase-Locked States – Update
Thierry Dudok de Wit, CNRS and University of Orléans, France
How Different did the Solar UV Irradiance Evolve during the Last Solar Cycle?
Thierry Dudok de Wit and Matthieu Kretzschmar, CNRS and University of Orléans, France
Online Nowcast and Forecast of the Solar Spectral Irradiance
Wolfgang Finsterle, Physikalisch-Meteorologisches Observ./WRC, Davos, Switzerland
The TIM-to-WRR Comparison
Claus Fröhlich, Physikalisch-Meteorologisches Observ./WRC, Davos, Switzerland
Solar Spectral Irradiance during Solar Cycle 23 from SPM/VIRGO Observations: An Update
Matthieu Kretzschmar, Royal Observatory of Belgium/CNRS, Univ. of Orleans, France
Small Flares Contributing to Total Solar Irradiance Variations
Doug Lindholm, LASP, Univ. of Colorado, Boulder
SORCE Solar Irradiance Data Products and the LASP Interactive Solar Irradiance Data
Center (LISIRD)
Nicola Scafetta, ACRIM, Duke University, Durham, North Carolina
Are Solar Irradiance Cycles Linked to the Planetary Oscillations?
James Struck, Evanston, Illinois
Comparing Our Sun to Observations of Supernova-Nova-Exploding-Changing Stars-Exploring the
Bethe Carbon Cycle Model through Comparison to Recent Changes in Stars
Hari Om Vats, Astronomy Astrophysics Division, Physical Research Laboratory, Ahmedabad,
India; and Niraj Pandya, Tolani College of Arts and Science, Adipur, Gujarat, India
Asymmetric Distribution of Solar X-Ray Flares
Guoyong Wen, NASA Goddard Space Flight Center, Greenbelt, Maryland; and
GESTART/Morgan State University
Application of a Coupled Ocean-Atmosphere Radiative-Convective Model to Study the
Temperature Response in Spectral Solar Variability on Decadal and Centennial Time Scales
Kok Leng Yeo, Max-Planck-Institut für Sonnensytemforschung, Katlenburg-Lindau, Germany
Comparing Irradiance Reconstructions from HMI/SDO Magnetograms with SORCE Observations
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Mind the Gap: How well can SFO ground-based photometry construct future missing TSI
measurements?
Angela Cookson [angie.cookson@csun.edu], Gary Chapman, and Dora Preminger, San
Fernando Observatory, California State University, Northridge
Use of multi-wavelength ground-based photometric data has been debated as a way to bridge gaps
in spacecraft TSI measurements. To assess the ability to produce meaningful TSI values from
photometric data, based on fits to existing TSI measurements, we look at single-instrument TSI
measurements for the 7-year period 2003-03-02 to 2010-05-03. These instruments either stand alone
(SORCE/TIM) or are incorporated into long-term TSI composites (PMOD/VIRGO, IRMB/VIRGO,
and ACRIMSAT/ACRIM3). We regress TSI from each instrument against ∑r and ∑K, photometric
indices derived from San Fernando Observatory (SFO) full-disk images at 672.3 nm (red) and 393.4
nm (Ca II K-line), for this period. Based on the regression coefficients, we construct artificial TSIs
for each instrument going backwards in time to encompass the full 21-year SFO dataset, comparing
each of these artificial datasets with each of the TSI composites. E.g., ∑ r and ∑ K fit to SORCE TSI
gives R2=0.947. The SORCE and PMOD/VIRGO correlation for the same period is R2=0.96. The 7year correlation between PMOD/VIRGO and the artificial SORCE TSI is R2=0.917, while the 21year correlation for the PMOD composite and the long-term artificial SORCE TSI is R2=0.854. The
other instruments give similar, but less-well correlated, results. With long-term photometric datasets,
we can produce meaningful TSI values for short-term data gaps, help to scale values from multiple
instruments, and identify instrument anomalies.
Topology of Earth’s Climate Indices and Phase-Locked States – Updated
David Douglass[douglass@pas.rochester.edu], University of Rochester, New York
Phase-locked states in Earth’s climate system were identified in a study of a set of climate indices by
Swanson and Tsonis (2009) (ST). They reported five climate shift events since 1900 based upon
features in a phase-locking parameter S. The present study finds that sets of climate indices have
important topological properties such as a metric diameter D that describes the magnitude of phase
locking among the indices. Minima in D as a function of time are shown to be associated with climate
shifts. Eighteen strong events since 1870 are identified, including the five reported by ST. Ten of these
minima correspond to reported events such as the well documented “climate shift of the mid-1970s” and
the more recent climate shift of 2001–2002. Most climate shifts tend toward radiative equilibrium.
How Different did the Solar UV Irradiance Evolve During the Last Solar Cycle?
Thierry Dudok de Wit [ddwit@cnrs-orleans.fr] 1, Gael Cessateur1,2, Matthieu Kretzschmar1, and
Luis Vieira1
1
University of Orléans, France; 2Institute of Planetology and Astrophysics of Grenoble (IPAG), France
Recent observations from SORCE/SIM suggest that during the last solar cycle the spectral
irradiance in the UV may have decreased by a factor larger than that observed during the 2 previous
cycles. This analysis, however, is complicated by the lack of continuous observations and thus
requires the stitching together of several records that do not always agree.
Deland and Cebula [JGR, 2008] already built a single composite database by merging different
data observations. Here, we use a novel approach that allows to stitch these records together in a
self-consistent way [Dudok de Wit, A&A 2011], thereby providing improved reconstructions of the
last three solar cycles.
Using these new reconstructions we investigate the variability in the solar spectral irradiance
(amplitude, phase lag) for each cycle and assess how different the last one actually was.
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Online Nowcast and Forecast of the Solar Spectral Irradiance
Thierry Dudok de Wit [ddwit@cnrs-orleans.fr] and Matthieu Kretzschmar, CNRS and
University of Orléans, France
The TIM-to-WRR Comparison
Wolfgang Finsterle [wolfgang@pmodwrc.ch], A. Fehlmann, and M. Suter, PMOD, World
Radiation Center, Davos Dorf, Switzerland; and G. Kopp and K. Heuremann, LASP, University
of Colorado-Boulder, Colorado
In the course of our ongoing efforts to make space-borne TSI measurements traceable to ground
based irradiance standards the TIM Witness radiometer was calibrated against the World
Radiometric Reference (WRR). This long awaited calibration provides an important link between
the SI and the WRR scale, which are suspected to differ by ~0.3%. The calibration took place in the
course of the 11th International Pyrheliometer Comparison between September 27 and October 15
2010 in Davos, Switzerland. The IPC-XI was organized under the auspices of WMO with
participation from over 100 national standard pyrheliometers from all over the world. The TIM was
operated on the solar tracking platform alongside the World Standard Group (WSG) of
pyrheliometers. Favorable weather conditions yielded 11 days worth of data with irradiance levels
ranging up to 1000 W/m2. We will set forth the methods which were applied to homogenize
circumsolar radiation for the different viewing geometries of the TIM and the WSG and finally
present and discuss the calibration results.
Solar Spectral Irradiance during Solar Cycle 23 from SPM/VIRGO Observations: An Update
Claus Fröhlich [cfrohlich@pmodwrc.ch], Physikalisch Meteorologisches Observatorium Davos
(PMOD), World Radiation Center (WRC), Davos, Switzerland
The preliminary results presented at the AGU Fall Meeting 2010 have been updated to May 2011
and the evaluation finalized. A major result is that the records at all three records are positively
correlated with the solar cycle with amplitudes relative to TSI of about 0.5 at 862 nm, 1.9 at 500 nm,
and 2.8 at 402 nm. Details of the degradation corrections applied in the evaluation are presented.
Small Flares Contribute to Total Solar Irradiance Variations
Matthieu Kretzschmar1,2[matthieu.kretzschmar@cnrs-orleans.fr], T. Dudok de Wit2, and R. Grappin3
1
Royal Observatory of Belgium / SIDC, Brussels, Belgium
LPC2E, UMR6115 CNRS /University of Orléans, France
3
LUTH/Observatoire de Paris Meudon, France
2
Sun-as-a-star observations of flares provide insight in the contribution of flare to solar and stellar
variability. Flares are well known to radiate energy at all wavelengths, but only extremely large
flares have been detected individually in total solar irradiance (TSI). Superposed epoch analysis of
solar fluxes, however, reveals that the total flare emission, at least down to C-class flare, is larger
than previously thought (Etot ~100. ESXR) and is dominated by emission in the visible and near UV
spectral range. This emission is hardly observed because of the very faint contrast in solar images
and the lack of dedicated space instrumentation.
The flare frequency distribution is well known to follow a power law, f(El)~El-a ; whether the
exponent a is smaller or larger than 2 determines if large (a < 2) or small (a > 2) flares dominates the
energy radiated by all flares at any time on the Sun. Previous studies found ~1.6 < a < ~2.5,
depending on the observed wavelength l, the flare detection algorithm and the fitting procedure.
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Here, we determine the first estimate for the total flare emission Etot and we find that a ~2.5,
i.e. small flares dominate the total flare emission. Therefore, the actual contribution of flares to
TSI variations depends on the smallest flare energy and on the variability of the flaring rate. We
discuss possible scenarios and provide estimates for the flare contribution to TSI variations.
SORCE Solar Irradiance Data Products and the LASP Interactive Solar Irradiance Data
Center (LISIRD)
Doug M. Lindholm [doug.lindholm@lasp.colorado.edu], C. K. Pankratz, B. G. Knapp, J.
Fontenla, J. W. Harder, W. E. McClintock, G. Kopp, M. Snow, and T. N. Woods, Laboratory for
Atmospheric and Space Physics (LASP), University of Colorado, Boulder.
The Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado
manages the Solar Radiation and Climate Experiment (SORCE) Science Data System. This data
processing system routinely produces Total Solar Irradiance (TSI) and Spectral Solar Irradiance
(SSI) data products, which are formulated using measurements from the four primary instruments on
board the SORCE spacecraft along with calibration data and other ancillary information to correct
for all known instrumental and operational factors. The TIM instrument provides measurements of
the TSI, whereas the SIM, SOLSTICE, and XPS instruments collectively provide measurements of
the solar irradiance spectrum from 1 nm to 2400 nm (excluding 31-115 nm). "Level 3" data
products (time-averaged over daily and six-hourly periods and spectrally re-sampled onto uniform
wavelength scales) are routinely produced and delivered to the public via the SORCE web site
(http://lasp.colorado.edu/sorce/data/), and are archived at the Goddard Earth Sciences (GES) Data
and Information Services Center (DISC). The SORCE data are also available from the LASP
Interactive Solar Irradiance Data Center (LISIRD) web site (http://lasp.colorado.edu/lisird/) which
provides access to over 25 years of LASP's solar irradiance measurements and is evolving to become
the ultimate source of solar irradiance data products. The data are also available to computer
programs via the LASP Time Series Server (LaTiS, which powers LISIRD). This poster provides an
overview of the SORCE solar irradiance data products, including quality and availability, as well as
current and planned data access capabilities.
Are Solar Irradiance Cycles Linked to the Planetary Oscillations?
Nicola Scafetta [nicola.scafetta@gmail.com], ACRIM, Duke University, Durham, North Carolina
Rudolf Wolf (1859) hypothesized that the 11-year solar cycle is driven by Jupiter and Saturn.
This theory has not found many estimators among solar scientists. However, the fact is that up the
current times the traditional solar theories have not explained the cycles at multiple time scales
observed in the solar activity. Indeed, the Schwabe solar cycle length appears constrained by a
bimodal dynamics. This is made of two harmonic attractors with periods at about 10 years and 12
years, respectively. Other multidecadal and multisecular cycles are found in longer cosmogenic
records that are commonly associated to solar variations. We show that these cycles appear to be
closely associated to planetary cycles. For example, the two side frequencies of the Schwabe solar
cycle appear to be related to the spring tidal period of Jupiter and Saturn (about 9.5-10.5 years) and
to the tidal sidereal period of Jupiter (about 11.86 years), respectively, which are the two major
planetary tidal cycles within the Schwabe frequency band. We show that a simplified harmonic
constituent model based on planetary periods and phases can reconstruct several solar cycles at
multiple scales including the known prolonged periods of low solar activity during the last
millennium such as the Oort, Wolf, Sporer, Maunder and Dalton minima and quasi-millennial
cycles. A preliminary discussion on the possible physical mechanisms involved in the process is
added.
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Comparing Our Sun to Observations of Supernova-Nova-Exploding-Changing StarsExploring the Bethe Carbon Cycle Model through Comparison to Recent Changes in Stars
James T. Struck [accelinflation@yahoo.com], Evanston, Illinois
This presentation, letter chooses stars which have recently collapsed, exploded,
behaved differently or gone through supernovae to understand our Sun in comparison with
those stars. We will use the Astrophysics Data System and www.nasa.gov to uncover some
recent popularly discussed stars and compile some of the previous characteristics of those
stars that changed recently. Then our Sun's characteristics will be compared to those
changed stars' characteristics to determine if our Sun shares any features of recently altered
stars. Supernovae 1987A is an example of a recently changed star that will be compared to
our Sun's characteristics. Comparisons are criticized as faulty or simplistic, but may yield
insights into what significance the Bethe Carbon Cycle standard model has or if the model
really is too simplistic as the Bethe model was partly constructed while riding a train
separate from observations.
Asymmetric Distribution of Solar X-ray Flares
Hari Om Vats [vats@prl.res.in], Astronomy Astrophysics Division, Physical Research
Laboratory Ahmedabad, India; and Niraj Pandya, Tolani College of Arts and Science, Adipur,
Gujarat, India
Solar flares are generally examined as individual events in great detail. The advent of
spacecraft observations of flares in hard and soft X-rays has provided data sets that are
naturally suited to statistical examination. Statistical studies have brought a new perspective
to flare physics, providing theorists with ideas for the physical mechanism underlying flares.
In particular, the recognition that the frequency distribution of the size of solar flares is a
power law a property flares share with diverse physical phenomena. We pursued a statistical
study of the X-ray flares using X-ray observation of GOES satellites for more than a solar
cycle. The investigations reveal that x-ray flares have preferential location on the solar
surface. Two examples are (1) out of 1077 total number X-ray flares in 1993; 55% occurred
in northern hemisphere. The flare occurrence peaks at ~ 12.5 degree both in north and south.
The peak in the northern hemisphere is considerably higher than that in south. (2) Out of
1962 total number of X-ray flares in 2004; 58% are in the southern hemisphere. Here too
peak occurrence is ~12.5 degree both in north and south, however, southern peak is higher
than that in north. The distribution of peak and average flux during the flares in these years
also have asymmetry, but of opposite sign. The analysis of other years is going on and in this
article we will present these results and discuss their implications.
Application of a Coupled Ocean-Atmosphere Radiative-Convective Model to Study the
Temperature Responses to Spectral Solar Variability on Decadal and Centennial Time Scales
Guoyong Wen1,2, Robert F. Cahalan1, Peter Pilewskie3, and Jerald W. Harder3
1
NASA/Goddard Space Flight Center, Greenbelt, Maryland; 2 GESTART/Morgan State
University; 3 LASP, University of Colorado-Boulder
We describe a time and height dependent RCM that couples the ocean with the
atmosphere, from upper stratosphere to deep ocean. We study the temperature responses
computed using the RCM, assuming different scenarios of spectral solar variability on
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decadal to centennial time scales. We show that the temperature responses are sensitive to the
relative phases of UV, visible, and near-IR variations in solar spectral. In particular the outof-phase variations such as those seen by SIM on SORCE have much larger impact on upper
stratospheric temperature and significantly smaller impact on surface and ocean
temperatures.
Comparing Irradiance Reconstructions from HMI/SDO Magnetograms with
SORCE Observations
K. L. Yeo1, S. K. Solanki1,2, N. A. Krivova1
1
2
Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany;
School of Space Research, Kyung Hee University, Yongjin, Gyeonggi, Korea
There is growing evidence the variation in solar irradiance, measured since 1978, has an
effect on Earth's climate. Of the models proposed to account for the observed variance, the most
successful are based on the assumption that the evolution of the solar surface magnetic field is
directly responsible. The reliable modelling of irradiance variation under this assumption is
contingent on the availability of high-quality full-disc magnetograms. Before HMI/SDO was
operational, MDI/SOHO observations were the best available and employed extensively for the
purpose. The use of HMI observations, which surpasses the MDI both in terms of resolution and
noise performance, represents the next step forward in progressing said models. Also, after MDI
is taken offline, HMI will be the only space-borne sensor returning full-disk magnetograms.
Here we present preliminary total and spectral irradiance reconstructions from HMI observations
and compare them to corresponding TIM and SIM measurements from the SORCE mission.
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