Decadal Cycles in the Sun, Sun-like Stars, and Earth s Climate System

Transcription

1 Decadal Cycles in the Sun, Sun-like Stars, and Earth s Climate System SORCE Science Meeting Sedona, Arizona * Sept , 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 1

2 Mind the Gap: How well can SFO ground-based photometry construct future missing TSI measurements? Angela Cookson 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 to 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 nm (red) and 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 R 2 = The SORCE and PMOD/VIRGO correlation for the same period is R 2 =0.96. The 7- year correlation between PMOD/VIRGO and the artificial SORCE TSI is R 2 =0.917, while the 21- year correlation for the PMOD composite and the long-term artificial SORCE TSI is R 2 = 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 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 Cessateur 1,2, Matthieu Kretzschmar 1, and Luis Vieira 1 1 University of Orléans, France; 2 Institute 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. 2

3 Online Nowcast and Forecast of the Solar Spectral Irradiance Thierry Dudok de Wit and Matthieu Kretzschmar, CNRS and University of Orléans, France The TIM-to-WRR Comparison Wolfgang Finsterle 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 11 th International Pyrheliometer Comparison between September 27 and October 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/m 2. 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 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 Kretzschmar 1,2 [matthieu.kretzschmar@cnrs-orleans.fr], T. Dudok de Wit 2, and R. Grappin 3 1 Royal Observatory of Belgium / SIDC, Brussels, Belgium 2 LPC2E, UMR6115 CNRS /University of Orléans, France 3 LUTH/Observatoire de Paris Meudon, France 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 (E tot ~100. E SXR ) 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(e l )~E l -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. 3

4 Here, we determine the first estimate for the total flare emission E tot 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 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 ( 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 ( 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 years) and to the tidal sidereal period of Jupiter (about 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. 4

5 Comparing Our Sun to Observations of Supernova-Nova-Exploding-Changing Stars- Exploring the Bethe Carbon Cycle Model through Comparison to Recent Changes in Stars James T. Struck 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 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 Wen 1,2, Robert F. Cahalan 1, Peter Pilewskie 3, and Jerald W. Harder 3 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 5

6 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. Yeo 1, S. K. Solanki 1,2, N. A. Krivova 1 1 Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany; 2 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. 6