Solar Metrology, Needs and Methods II

Sep 21, 2015, 8:00 AM → Sep 23, 2015, 6:00 PM Europe/Brussels

Meridian Room (Royal Observatory of Belgium)

Alain Hauchecorne, David Bolsée, Marie Dominique (ROB), Michel Rouzé, Mustapha MEFTAH, Rock Bush (Stanford University), Steven Dewitte

One year after the first meeting in Paris, the CNES, the LATMOS and the STCE are happy to invite you at the second edition of the meeting "Solar Metrology, Needs and Methods". This meeting is open to anyone involved in solar metrology and modelling. It intends to review the recent progresses in those two fields, to analyze the possibilities, but also the limitations of the current ground- or space-based observation facilities, and to discuss the major challenges for future missions. 

Monday, September 21

12:15 PM → 1:55 PM Welcome and lunch

1:55 PM → 2:00 PM Introduction

Speaker: Dr Mustapha Meftah (CNRS-LATMOS)

2:00 PM → 2:30 PM The RMIB space odissey: new frontiers.

The Royal Meteorological Institute of Belgium has a long history in space instrumentation with in total 11 space flights with 6 different instruments for the measurement of Total Solar Irradiance (TSI) since 1983. It also has expertise in the measurement of the Earth Radiation Budget with the data processing of the Geostationary Earth Radiation Budget instrument since 2003. In this talk I will present the future RMIB space projects Diarad/Joim on FY3E and the Simba cubesat project. FY3E will be the 5th satellite of the Second Generation Chinese operational meteorological polar satellites FY3, with foreseen launch in 2018, and it will be the first operational meteorological polar satellite in the early morning dusk/dawn orbit with 6/18 equator crossing times. This orbit is similar to the one of Picard, and is ideally suited for solar observation. Moreover, the design lifetime is 8 years, which makes it ideally suited for long term solar observation. The RMIB, with its partners Latmos and Bira, will deliver a DIARAD instrument as part of the Joint Irradiance Monitoring (JOIM) experiment on FY3E. This instrument will continue the very successfull TSI variability monitoring of the DIARAD/VIRGO instrument on SOHO since 1996. For an improved determination of the absolute value of the Solar Constant, the instrument will have a variable aperture geometry allowing to compare the classical geometry with an inner precision aperture to the alternative TIM type geometry with an outer precision aperture. Finally, the instrument will have a broadband IR filter to measure the absolute level of the solar IR spectrum. Altough it is generally accepted that the climate on earth is changing due to a radiative energy imbalance at the top of the atmosphere, up to now this radiation imbalance has not been measured directly. The measurement is challenging both in terms of space-time sampling of the radiative energy that is leaving the earth and in terms of accuracy. The incoming solar radiation and the outgoing terrestrial radiation are of nearly equal magnitude - of the order of 340 W/m² - resulting in a much smaller difference or imbalance of the order of 0.5 W/m². The only way to measure the imbalance with sufficient accuracy is to measure both the incoming solar and the outgoing terrestrial radiation with the same instrument. The RMIB and its partners KUL, ISIS, the University of Stellenbosch, Latmos, ROB, VUB, Belspo and ESA are currently developing the Sun-earth IMBAlance (SIMBA) In orbit Demonstration cubesat to test out the new idea of measuring the incoming solar and outgoing terrestrial radiation with a single instrument on a cubesat specifically designed for this instrument. The instrument is the adaptation of the DIARAD type radiometer to a Wide Field Of View radiometer. The currently foreseen launch for Simba is in 2018.

Speaker: Dr Steven Dewitte (RMIB)

2:30 PM → 3:00 PM Can we use stellar photometric data to better understand solar variability?

Despite significant progress our understanding of solar brightness variation is still incomplete. In particular, the magnitude and even the phase (in the visible part of the spectrum) of the solar brightness variation over the course of the activity cycle remain highly controversial. Also the magnitude of solar irradiance changes on centennial and longer time scale is uncertain. An alternative way to improve and deepen our understanding of solar variability on all time scales is to test and validate the available solar models against photometric records of Sun-like stars. The solar-stellar comparative studies are starting to attract attention and has already been employed in the literature to constrain solar brightness variability. The interest in solar-stellar comparison has been recently rekindled by the launch of the Kepler and Corot space missions and anticipation of the TESS and PLATO missions. We give an overview of recent progress in the area and discuss how solar and stellar research may benefit from the mutual synergies.

Speaker: Dr Alexander Shapiro (Max-Planck-Institut für Sonnensystemforschung)

3:00 PM → 3:30 PM On long-term behavior of North-South Asymmetry of Solar Phenomena

V. K. VERMA Uttrakhand Space Application Center, Dehradun, India vkvermadr@rediffmail.com

Speaker: Dr VIRENDRA VERMA (UTTRAKHAND SPACE APPLICATION CENTER, DEHRADUN, INDIA)

3:30 PM → 4:00 PM 2016 transit of Mercury and the solar diameter: new opportunities after the Venus transits

The use of the planetary transits to measure the solar diameter exploits the accurate timing of the ingress and the egress of Mercury or Venus on the solar disk at relative radial angular velocities of 0.05 arcsec per second of time. Our analysis of the transits of Venus 2012 (observed in Huairou, China) and 2004 (in Rome and Athens) overcomes the famous black drop effect and it is presented in view of the forthcoming transit of Mercury of May 9, 2016. In particular the accuracy of the planetary ephemerides and some technical observational tips are considered to apply this historical method by observing only the ingress of the 2016 transit, as it will be possible for the majority of the European sites. The educational and scientifical opportunities offered by these measurements are discussed.

Speaker: Dr Costantino Sigismondi (ICRA)

4:00 PM → 4:15 PM Coffee

4:15 PM → 4:45 PM SUITS /SWUSV : A Solar - Terrestrial Space Weather & Climate Investigation

We present the SUITS/SWUSV microsatellite mission investigation: "Solar Ultraviolet Influence on Troposphere/Stratosphere, a Space Weather & Ultraviolet Solar Variability" mission. SUITS/SWUSV was developed to determine the origins of the Sun’s activity, understand the flaring process (high energy flare characterization) and onset of CMEs (forecasting). Another major objective is to determine the dynamics and coupling of Earth’s atmosphere and its response to solar variability (in particular UV) and terrestrial inputs. It therefore includes the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging) and the solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance measures from 170 to 400 nm). The mission is on a sunsynchronous polar orbit 18h-6h (for almost constant observing) and proposes a 7 instruments model payload of 65 kg - 65 W with: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV (200–220 nm Herzberg continuum) imaging (sources of variability); SOLSIM (Solar Spectral Irradiance Monitor), a spectrometer with 0.65 nm spectral resolution from 170 to 340 nm; SUPR (Solar Ultraviolet Passband Radiometers), with UV filter radiometers at Lyman-Alpha, Herzberg, MgII index, CN bandhead and UV bands coverage up to 400 nm; HEBS (High Energy Burst Spectrometers), a large energy coverage (a few tens of keV to a few hundreds of MeV) instrument to characterize large flares; EPT-HET (Electron- Proton Telescope – High Energy Telescope), measuring electrons, protons, and heavy ions over a large energy range; ERBO (Earth Radiative Budget and Ozone) NADIR oriented; and a vector magnetometer. Complete accommodation of the payload has been performed on a PROBA type platform very nicely. Heritage is important both for instruments (SODISM and PREMOS on PICARD, LYRA on PROBA-2, SOLSPEC on ISS, …) and platform (PROBA-2, PROBA-V, ...), leading to high TRL levels (>7). SUITS/SWUSV was designed in view of the ESA/CAS AO for a Small Mission; it could now be envisaged for a joint opportunity CNES/NASA (Heliophysics Explorer Mission of Opportunity?) between Europeans and Americans partners for a possible flight in 2021-2022 or proposed, in an enhanced version, for the future ESA M5 mission.

Speaker: Dr Luc Dame (LATMOS)

4:45 PM → 6:00 PM Solspec Discussion

Tuesday, September 22

9:30 AM → 10:00 AM Total Solar Irradiance measurements over the last 30 years and reconstruction over the last 300 years.

The Total Solar Irradiance quantifies the amount of energy that the earth receives from the Sun. The quantification of the TSI variability is important to understand whether the sun can have a significant influence on climate change on earth. A carefull analysis of the TSI space measurements over the last 30 years indicates that within a measurement uncertainty of 0.1 W/m²decade the long term TSI variation can be fully explained by the 'magnetic ingredients' of sunspots and facula associated to the 11 year solar activity cycle. Further analysis of the Ca II K index measured from Mount Willson observatory for the last 100 years and of the revised sunspot time series for the last 300 years indicates that contrary to the long-held paradigm of a 'modern grand solar maximum' we are currently in the minimum of a long term modulation of the amplitude of the 11 year cycle; this amplitude modulation has a periodicity around 100 year. The determination of the absolute value of the TSI - also known as the Solar Constant - is a problem of metrology. Our new best estimate of 1362.9 +/- 0.9 W/m² at solar minimum is derived from the revised absolute value measured by the DIARAD/SOVIM instrument on the ISS in 2008. Compared to earlier versions of the DIARAD TSI evaluation we apply a new method for the determination of the so-called non-equivalence between electrical and optical power. This new evaluation method was validated during a laboratory measurement campaign at the LASP TRF facility in 2013. During this same campaign we identified an underestimation of the irradiance measured by the LASP TRF cryogenic radiometer, which after elimination of all other possible causes can only be attributed to an underestimation of the amount of scattering and diffraction occuring around the LASP TRF primary aperture. Since the TIM/SORCE space radiometer has a similar geometry and TSI evaluation method as the LASP TRF cryogenic radiometer, this suggests that the TIM/SORCE radiometer measures a too low TSI value.

Speaker: Dr Steven Dewitte (RMIB)

10:00 AM → 10:30 AM Solar forcing of the Earth climate: the role of the middle atmosphere-troposphere coupling.

The variability of the solar irradiance may have an impact of the Earth climate by changing the input of energy absorbed at the surface and in the atmosphere. However the amplitude of this impact is still very badly known due to the complexity of the processes involved in the solar forcing of the Earth atmosphere. Two main mechanisms have been proposed. The “bottom-up” forcing is the direct absorption of the visible and near IR solar irradiance by the surface. However the variability of the solar irradiance in these wavelengths bands is no more than 0.1% over an 11-year solar cycle and the impact on the global temperature at the surface is expected to be limited according to the last IPCC assessment. The “top-down” forcing is the related to the 5 to 10% change in the UV solar irradiance, which modifies the production of stratospheric ozone and the temperature of the middle atmosphere, inducing a dynamical coupling with the troposphere. In particular the rate of occurrence and the characteristics of polar Sudden Stratospheric Warmings (SSWs) can be affected. Recent studies have shown that temperature and pressure perturbations induced by SSWs can propagate down to the ground and can enter in resonance with modes of the tropospheric circulation like the Artic Oscillation/North Atlantic Oscillation (AO/NAO). The NAO is characterized by the pressure gradient between subtropical and Arctic latitudes over the North Atlantic. It is a dominant mode of the climate over Europe. A positive NAO phase will lead to weather warmer and wetter than normal in most of Europe and drier over the Mediterranean area. The reverse is observed with a negative NAO phase. Global climate modelling and observations have shown that a high solar activity favours the positive NAO phase and a low solar activity favours the negative NAO phase. This mechanism can explain part of the observed variability of the climate in the North hemisphere in correlation with the solar activity and is in agreement with a colder temperature above Europe during the Maunder minimum.

Speaker: Dr Alain Hauchecorne (CNRS-LATMOS)

10:30 AM → 10:45 AM Coffee

10:45 AM → 11:15 AM Measurements of the Solar Oblateness during the SDO Mission

During the five plus years of the Solar Dynamics Observatory (SDO) spacecraft on-orbit operation, the Helioseismic and Magnetic Imager (HMI) instrument has been measuring the shape of the Sun. To date, twelve roll maneuvers have been performed by the SDO spacecraft during which the spacecraft is rotated 360 degrees around the Sun-spacecraft line. HMI observations taken during these roll maneuvers enable the instrument distortion to be separated from the solar shape. The mean equator to pole radius difference over the five years of observations is approximately 6.0 milli-arcseconds. The long term trend of the solar oblateness, however, does not show a correlation with the current solar sunspot cycle. Details on the HMI instrument thermal variation during the roll maneuvers will be discussed. In particular, the thermal control of the HMI optical bench was modified in 2013 after which there was a statistically significant decrease in the solar oblateness determined from the HMI observations.

Speaker: Dr Rock Bush (Stanford University)

11:15 AM → 11:45 AM Projet SOLIMB : métrologie du bord du soleil et détermination de son diamètre pendant les éclipses solaires

We report on a novel technique of measuring the solar radius during total solar eclipses that exploits light curves recorded just before and after the second and third contacts. The measurements are performed by pre-programmed photometers deployed over the eclipse paths and operating unattended. The recorded light curves are compared to synthetic ones calculated from high accuracy ephemerides and lunar limb profiles constructed from the topographic model of the Moon provided by the Kaguya lunar space mission. A minimization process between the two sets of curves yields the solar radius. Altogether, seventeen determinations have been obtained at the past four total eclipses with the following averages (at a wavelength of 540 nm and scaled to 1 AU): 959.94±0.02 arcsec on 11 July 2010, 960.02±0.04 arcsec on 13 November 2012, 959.99±0.09 arcsec on 3 November 2013, and 960.01±0.09 arcsec on 20 March 2015. Part of the differences between these four values may be attributed to weather conditions. Averaging the whole set of measurements yield a radius of 959.99±0.06 arcsec (696,246±45 km), in excellent agreement with the most recent data and supporting an upward revision of the standard IAU value as already suggested.

Speaker: Dr Philippe Lamy (LAM)

11:45 AM → 12:15 PM Using HMI-SDO for limb seismology

Some of the earliest searches for global solar observations were obtained using the solar limb. Before p-modes had been clearly established by full-disk measurements, the solar limb offered a relatively simple opportunity for measuring the effects of local solar atmosphere oscillatory temperature and opacity changes, and effects from potentially small Lagrangian radial displacements in the solar limb due to interior oscillations. First thoughts might suggest that a time-series of effectively one-dimensional limb measurements couldn't compete with the physical information content of two-dimensional full-disk observations for a solar oscillation spectrum as complex as we know the p-mode spectrum to be. Yet, because high accuracy limb data can now be obtained with sufficient temporal resolution to isolate otherwise spatially degenerate modes in the limb-only data, and because the limb data sample a unique weighting of p-mode properties, there is reason to further develop some techniques of "limb-helioseismology." The other compelling reason for limb-helioseismology is that the existence of limb measurements from space, where there is no incoherent terrestrial image distortion noise, allows the solar limb to be measured astrometrically with exquisite precision. This means that oscillatory changes in spatial limb-harmonics, e.g. in data from HMI, can be measured even with sub-microarcsecond astrometric amplitudes. Individual spherical harmonic p-modes are detected in full-disk data with amplitudes of a few 10's of cm/s. This corresponds to 5-minute period oscillatory displacement amplitudes at the limb at the micro-arcsecond level. In this work we present results from Individual spherical harmonic p-modes that were detected around solar limb with amplitudes at the micro-arcsecond level from three years of measurements using the Helioseismic and Magnetic Imager (HMI) abord the Solar Dynamics Observatory (SDO). Those measurements of 5-min p-modes, while having many similarities to full-disk doppler observations, have significantly different sensitivities to the solar rotation and the 5-min mode solar atmospheric structure. These may provide information about the solar structure which is complementary to full-disk measurements.

Speaker: Prof. MARCELO EMILIO (Ponta Grossa State University)

12:15 PM → 1:45 PM Lunch

1:45 PM → 2:15 PM Mid-term Periodicities of the LYRA data spectrum

The spectra of the PROBA2/LYRA data, similarly to every other solar time series, show predominant periodicities that can be of solar or of instrumental origin. In this paper, after assessing the validity of the LYRA time series by cross-calibrating them to SDO/EVE, we compare the main periodicities characterizing the LYRA spectrum to the ones found in the sunspot number, in the 10.7 cm flux, in a X-ray flare index, and in the sunspot area evolution. We mainly focused on the 2010 to 2014 time-range, for which the LYRA data are available.

Speaker: Dr Laurence Wauters (ROB)

Slides talk_sep_2015.pdf

2:15 PM → 2:45 PM Long-term variability of LYRA data

The nominal response of the LYRA channels and the way they degraded over the mission will be shown, in order to explain what we actually observe. It will be demonstrated that LYRA's daily significant EUV minimum correlates with GOES soft X-ray levels, as well as daily sunspot numbers. LYRA long-term data can be a good (maybe even better?) indicator of solar variability.

Speaker: Mr Ingolf Dammasch (Royal Observatory of Belgium)

2:45 PM → 3:15 PM The value of the Solar Constant.

The determination of the absolute value of the TSI - also known as the Solar Constant - is a problem of metrology. Our new best estimate of 1362.9 +/- 0.9 W/m² at solar minimum is derived from the revised absolute value measured by the DIARAD/SOVIM instrument on the ISS in 2008. Compared to earlier versions of the DIARAD TSI evaluation we apply a new method for the determination of the so-called non-equivalence between electrical and optical power. This new evaluation method was validated during a laboratory measurement campaign at the LASP TRF facility in 2013. During this same campaign we identified an underestimation of the irradiance measured by the LASP TRF cryogenic radiometer, which after elimination of all other possible causes can only be attributed to an underestimation of the amount of scattering and diffraction occuring around the LASP TRF primary aperture. Since the TIM/SORCE space radiometer has a similar geometry and TSI evaluation method as the LASP TRF cryogenic radiometer, this suggests that the TIM/SORCE radiometer measures a too low TSI value.

Speaker: Dr Steven Dewitte (RMIB)

3:15 PM → 3:30 PM Coffee

3:30 PM → 4:00 PM Five Years of Solar Observation with PICARD

PICARD contains a double program with in-space and on-ground measurements. Space observations are a priori most favourable, however, space entails also technical challenges, a harsh environment, and a finite mission lifetime. The PICARD spacecraft, launched on June 15, 2010 was retired in April 2014. On ground, the instruments are less affected by in-space degradation and maintenance is easily provided so if the atmosphere is properly monitored and taken into account, they still represent an opportunity to generate the needed long-term time-series. That is why ground measurements have been carried out since May 2011 and are pursued after the space program. In this talk, we describe both sets of instruments and corrections, and then present our current results about solar radius variations after five years of solar observations.

Speaker: Mustapha Meftah (CNRS-LATMOS)

4:00 PM → 4:30 PM Solar Spectral Irradiance observations from the PICARD/PREMOS radiometer

Space weather and space climate studies require accurate Solar Spectral Irradiance (SSI) observations. The PREcision Monitoring Sensor (PREMOS) instrument aboard the PICARD satellite acquired solar irradiance measurements in specific spectral windows in the UV, visible and near infrared from October 2010 to March 2014. This contribution aims at presenting the Level 3 data, corrected for non solar features as well as for degradation. These level 3 data has been tested over different scientific cases, such as observations during the Venus transit and the presence of the p-mode signature within high-cadence data. The PREMOS Level 3 data have also been compared to others data sets, namely the SOLSTICE and SIM instruments aboard SORCE, for nearly 3 and half years. An excellent correlation has been found for the UV spectral ranges. We have also found a rather good correlation for visible and near-infrared observations for short-term variations, for which an error of about 200 ppm has been estimated within PREMOS visible and near-infrared observations. The PREMOS data could also be used to address several scientific topics, i.e. for validating semi-empirical models of the solar irradiance. We will emphasize about our new irradiance model, COSIR for Code of Solar Irradiance Reconstruction, which is successful at reproducing the solar modulation as seen in the PREMOS, SoHO/Virgo and SORCE data.

Speaker: Dr Gaël Cessateur (BIRA-IASB)

4:30 PM → 6:00 PM Metrology Discussion

7:00 PM → 10:30 PM Conference Dinner

Wednesday, September 23

9:00 AM → 9:30 AM The Solar Spectral Irradiance in the Near IR

Bolsée D., Pereira N. BIRA-IASB, 3 avenue Circulaire, 1180 Brussels, Belgium The Solar Spectral Irradiance measurements in the near-infrared spectral region are available from space since 20 years. Ground-based or airborne datasets are also available. Apparent discrepancies not in accordance with the standard uncertainty calculations have been found between the datasets. A review is presented on the instrumental causes of the discrepancies, the absolute calibration and instrument performances, in particular for SOLAR/SOLSPEC onboard the Internal Space Station and for IRESPERAD (ground-based measurements).

Speaker: Dr David Bolsée (BIRA-IASB)

9:30 AM → 10:00 AM The 2008 Minimum Solar Spectral Irradiance from ISS SOLAR Spectrometers Measurements

The SOLSPEC and SolACES are spectrometers onboard the SOLAR payload of the International Space Station (ISS). The solar spectral irradiance (SSI) measurements extend from 16 to 2900 nm. In 2008, a SSI minimum occurred, which is the lowest among the measurements carried out from 1978. The SSI reconstructions and measurements play an important role in climate modeling for providing SSI at different epochs i. e. different levels of solar activity. The solar activity in 2008 is the lowest since 1978. This allows checking the capability of different solar reconstructions to estimate their accuracy by comparison with measurements. Data from the SOLSPEC and SolACES spectrometers have been merged to generate a spectrum at solar minimum activity. Comparison with spectra obtained from other instruments running at the same time as well as with published spectra will be shown. The absorption coefficient of the negative ion of hydrogen has its minimum around 1600 nm so that measurements at this wavelength provide a unique opportunity to probe the deepest layers of the solar photosphere. This is why a specific attention will be given to the IR part of the spectrum in terms of absolute value, brightness temperature of the photosphere, and contribution to the total solar irradiance. For this period, a comparison with reconstructions such as SATIRE, NRLSSI and COSI models using either theoretical or empirical approaches will be used. Difference in terms of absolute values will be discussed.

Speaker: Dr Gerard Thuillier (LATMOS-CNRS, 11 blvd d’Alembert, 78280 Guyancourt, France)

10:00 AM → 10:30 AM The quest for understanding solar brightness variation. How can SOLSPEC contribute?

Although the measurements and modeling of the solar brightness variation were under active examination during the last few decades, the complete picture of the solar brightness variability is still unclear. Therefore the launch of every new space mission devoted to the measurements of the solar brightness is able to provide a crucial piece of complementary information, as well as to nourish theoretical models. We show how the SOLSPEC data may help to resolve a long-standing controversy about the magnitude and phase of solar brightness variations. We discuss a new generation of solar brightness variability models and show how the SOLSPEC data can help to constrain them.

Speaker: Dr Alexander Shapiro (Max-Planck-Institut für Sonnensystemforschung)

10:30 AM → 10:45 AM Coffee

10:45 AM → 11:15 AM Space-based instrument developments for UV solar observations - detector technology -

On November 2, 2009, PROBA2 was launched into a sun-synchronous polar orbit. Two solar observation experiments which are test platforms for new technologies, the Sun Watcher with Active Pixels and Image Processing (SWAP) and the Large-Yield RAdiometer (LYRA) onboard PROBA2 will be introduced. I will review the design of the instruments, provide an overview of their on ground calibration but also their on-orbit degradation effects. As a second topic, the SWORD radiometer for cubesat platform is introduced. SWORD stands for Solar Wide bandgap semicOnductor RaDiometer which is an alternative to Si technologies through the “Blind to Optical Light Detectors” (BOLD) project. The BOLD detectors under development are metal-semiconductor-metal photodetectors based on diamond and AlN materials which bring new possibilities for UV solar observations. As a last topic, I will introduce one of the main future space missions which is the Solar Orbiter. The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers and one dual-band full Sun imager telescopes that will provide EUV (17.4 and 30.4nm) and Lyman-α (121.6 nm) images of the solar atmospheric layers. For the EUI, CMOS Active Pixel Sensors (APS) prototype have been developed. A campaign of measurements to characterize their EUV properties and degradation mechanisms will be presented.

Speaker: Dr Ali BenMoussa (ROB/STCE)

11:15 AM → 11:45 AM Progress towards understanding the degradation affecting the PROBA2/LYRA instrument

In the quest of understanding and modeling the solar spectral irradiance, it is mandatory to make use of data originating from multiple sources, either as input of the models or for their validation. LYRA, the Large Yield Radiometer embarked on the European Space Agency Proba2 mission, is such a source of datasets. The instrument was launched on 2 November 2009 and acquires solar irradiance measurements in four broad spectral channels from the soft X-ray to the middle ultraviolet at high cadence (nominally 20 Hz). Nevertheless, the instrument suffered a very strong degradation starting immediately after launch. In this work, we present our analysis the observed degradation and on how it affects the use of the instrument for SSI modeling, as well as our efforts to incorporate a valid degradation correction in the calibration process.

Speaker: Marie Dominique (ROB)

11:45 AM → 12:15 PM The SOLSPEC Spectrometers onboard the International Space Station

The SOLSPEC spectrometer placed onboard the SOLAR payload of the International Space Station (ISS) measures the solar spectral irradiance (SSI) from 170 to 2900 nm. Data at first light in April 2008 appears consistent with the WHI spectrum as well as ATLAS 3. However, a degradation appeared especially in UV in relation with the deuterium lamps operations. When they were no more activated, the degradation significantly decreased. Another anomaly is shown in the raw data consisting in signal change at constant wavelength. We report the study of these two anomalies in view of possible corrections. We also show that despite a strong degradation and non-solar signatures in the data, SOLSPEC can clearly detect the variability of the solar irradiance on the timescale of the solar rotation.

Speaker: Dr Gerard Thuillier (LATMOS-CNRS)

12:15 PM → 12:30 PM Non-linearties in SODISM telescope

no content

Speaker: Dr Jean-François Hochedez (LATMOS)

12:30 PM → 1:45 PM Lunch

1:45 PM → 2:00 PM SERB, a nano-satellite dedicated to Sun-Earth relationship

The Solar irradiance and Earth Radiation Budget (SERB) is a future innovative proof-of-concept nano-satellite, with four ambitious science goals. The nano-satellite aims to measure on the same platform the different components of the Earth radiative budget, the solar energy input and the energy reemitted at the top of the Earth atmosphere, with a particular focus on the UV part of the spectrum and on the ozone layer, which are the most sensitive to solar variability. SERB is proposed for the nano-satellite program of Polytechnic School and CNES for a flight in 2020-2021. SERB is a triple Cubesat, under development by students, mostly working at Polytechnic School. Critical components of instrumental payloads of future large missions (coatings, UV filters, etc.) can acquire the technical maturity by flying in a CubeSat. Nano-satellites represent also an excellent alternative of instrumentation testing, providing longer flights than rockets. Moreover, targeted science can be performed by nano-satellites. Thus, this talk is intended to present a future space mission enabled by the development of nano-satellites and the underlying technologies they employ.

Speaker: Mustapha Meftah (CNRS-LATMOS)

2:00 PM → 2:30 PM Atmospheric Research and Monitoring with a SATellite (ARM-SAT) for Sun-Earth measurements

The ARM-SAT project aims to incorporate brand-new and even disruptive technologies enabling future cutting edge science and space applications for simultaneous Earth-Sun measurements (radiation, ozone, etc..). It represents also drastically increments in miniaturisation, power reduction, efficiency, versatility, and increased functionality.

Speaker: Dr Alain SARKISSIAN (LATMOS / UVSQ / UPMC / CNRS)

2:30 PM → 3:00 PM The new and improved Sunspot Number SN

We present the first end-to-end revision of the Sunspot Number since the creation of this reference index of solar activity by Rudolf Wolf in 1849. Most corrections rely entirely on original sunspot data, using various approaches. Newly recovered historical sunspot records were added and a critical data selection was applied for the 17th and 18th century, confirming the low solar activity during the Maunder Minimum. Over the 19th century, the k scaling coefficients of individual observers were recomputed using new statistical methodologies, like the "backbone" method resting on a chain of long-duration observers. In particular, we corrected a major inhomogeneity in 1947 in the Sunspot Number (~20% overestimate) caused by a weighting introduced by Pr. Waldmeier during the Zurich era. Finally, a full re-computation of the sunspot number was done over the last 50 years, using all original data from the 270 stations archived by the World Data Center - SILSO in Brussels. We conclude on the implications for solar cycle and Earth climate studies and on important new conventions adopted for the new series: new unit scales (constant "heritage" factors 0.6 and 12.08 dropped for the Sunspot and Group Numbers respectively), new SN and GN symbols and a new version-tracking scheme implemented at the WDC-SILSO, as a framework open to future improvements of those unique data series.

Speaker: Dr Laure Lefevre (Royal Observatory of Belgium)

3:00 PM → 3:15 PM Coffee

3:15 PM → 4:00 PM Discussion

4:00 PM → 4:05 PM Closure