A5026410870- Solar and Space Plasma Dynamics
- Solar Radiation and Photovoltaics
- Stellar, planetary, and galactic studies
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Calibration and Measurement Techniques
- Atmospheric and Environmental Gas Dynamics
- Astronomical Observations and Instrumentation
- Climate variability and models
- Global Energy and Sustainability Research
- Spacecraft Design and Technology
- Maritime and Coastal Archaeology
- Meteorological Phenomena and Simulations
- Space exploration and regulation
- Advanced Computational Techniques and Applications
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Conservation Techniques and Studies
- Impact of Light on Environment and Health
- Scientific Research and Discoveries
- International Science and Diplomacy
- Geophysics and Gravity Measurements
Max Planck Institute for Solar System Research
2013-2023
Max Planck Society
2014-2020
Technische Universität Braunschweig
2012-2013
Abstract. The pre-industrial millennium is among the periods selected by Paleoclimate Model Intercomparison Project (PMIP) for experiments contributing to sixth phase of Coupled (CMIP6) and fourth PMIP (PMIP4). past1000 transient simulations serve investigate response (mainly) natural forcing under background conditions not too different from today, discriminate between forced internally generated variability on interannual centennial timescales. This paper describes motivation experimental...
Total and spectral solar irradiance are key parameters in the assessment of influence on changes Earth's climate. We present a reconstruction daily obtained using SATIRE-S model spanning 1974 to 2013 based full-disc observations from KPVT, SoHO/MDI SDO/HMI. ascribes variation timescales greater than day photospheric magnetism. The spectrum is reconstructed apparent surface coverage bright magnetic features sunspots data modelled intensity spectra these structures. cross-calibrated various...
Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations timescales greater than a day being attributed to surface magnetic field. Independently, ground-based and suggest Sun-like stars show similar, but significantly broader pattern of photometric variability. To understand whether the stellar is consistent with paradigm we assess relative contributions faculae spots magnetically-driven We investigate how variability as well its facular...
The variation in the radiative output of Sun, described terms solar irradiance, is important to climatology. A common assumption that irradiance variability driven by its surface magnetism. Verifying this has, however, been hampered fact models based on magnetism have be calibrated observed variability. Making use realistic three-dimensional magnetohydrodynamic simulations atmosphere and state-of-the-art magnetograms from Solar Dynamics Observatory, we present a model total (TSI) does not...
Aims. This study aims at setting observational constraints on the continuum and line core intensity contrast of network faculae, specifically, their relationship with magnetic field disc position.
We present a new empirical model of total and spectral solar irradiance (TSI SSI) variability entitled EMPirical Irradiance REconstruction (EMPIRE). As with existing models, TSI SSI is given by the linear combination activity indices. In UV usually determined fitting rotational in indices to that measurements. Such models have date relied on ordinary least squares regression, which ignores uncertainty an advance from earlier efforts, accounted for EMPIRE application error-in-variables...
Abstract Total solar irradiance and UV spectral has been monitored since 1978 through a succession of space missions. This is accompanied by the development models aimed at replicating relating variability to magnetic activity. The Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) And REconstruction for Satellite era (SATIRE‐S) provide most comprehensive reconstructions total over period satellite observation currently available. There persistent controversy between various...
We present a reconstruction of the spectral solar irradiance since 1700 using SATIRE-T2 (Spectral And Total Irradiance REconstructions for Telescope era version 2) model. This model uses as input magnetograms simulated with surface flux transport fed semi-synthetic records emerging sunspot groups. used statistical relationships between properties group emergence, such latitude, area, and tilt angle, cycle strength phase to produce starting in year 1700. The semisynthetic are into obtain...
Context. Stellar spectral variability on timescales of a day and longer, arising from magnetic surface features such as dark spots bright faculae, is an important noise source when characterising extra-solar planets. Current 1D models faculae do not capture the geometric properties fail to reproduce observed solar facular contrasts. Magnetoconvection simulations provide contrasts accounting for geometry. Aims. We calculate contrast spectra magnetoconvection photosphere with view improve (a)...
How the solar electromagnetic energy entering Earth's atmosphere varied since pre-industrial times is an important consideration in climate change debate. Detrimental to this debate, estimates of total irradiance (TSI) Maunder minimum, extended period weak activity preceding industrial revolution, differ markedly, ranging from a drop 0.75 Wm-2 rise 6.3 Wm-2. Consequently, exact contribution by forcing global temperatures over past centuries remains inconclusive. Adopting novel approach based...
We reassess the relationship between photospheric magnetic field strength and Ca II K intensity for a variety of surface features as function position on disc solar activity level. This can be used to recover unsigned from images recorded in core line. have analysed 131 pairs high-quality, full-disc, near-co-temporal observations SDO/HMI Rome/PSPT spanning half cycle. To analytically describe observationally-determined relation, we considered three different functions: power law with an...
Magnetic features on the surface of stars, such as spots and faculae, cause stellar spectral variability time-scales days longer. For stars other than Sun, signatures faculae are poorly understood, limiting our ability to account for pollution in exoplanet transit observations. Here we present first facular contrasts derived from magnetoconvection simulations K0, M0 M2 main-sequence compare them previous calculations G2 stars. We simulate photospheres immediate subsurface layers types...
Accurate information on long-term variations in solar irradiance, important for understanding the influence Earth's climate, cannot be derived from direct irradiance measurements due to comparatively short lifetimes of space-borne experiments. Models using photospheric magnetic field as input can provide an independent assessment changes. The Spectral And Total Irradiance Reconstruction satellite era (SATIRE-S) model does just that. Unfortunately, magnetogram archives used by SATIRE-S...
Knowledge of solar irradiance variability is critical to Earth's climate models and understanding the influence on climate. Direct measurements are only available since 1978. Reconstructions past typically rely sunspot data. These provide indirect information facular network regions, which decisive contributors timescales cycle longer. Our ultimate goal reconstruct variations using historical full-disc Ca II K observations describe contribution independently observations. Here, we develop...
Abstract The emission in the near-ultraviolet Ca ii H and K lines is modulated by stellar magnetic activity. Although this emission, quantified via S -index, has been serving as a prime proxy of activity for several decades, many aspects complex relation between magnetism are still unclear. amount measured suspected to be affected not only intrinsic properties but also inclination angle rotation axis. Until now, such an effect on -index remained largely unexplored. To fill gap, we develop...
Aims. We present a point spread function (PSF) for the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) discuss effects of its removal on apparent properties solar surface phenomena in HMI data.
Context. Solar spectral irradiance (SSI) variability is one of the key inputs to models Earth's climate. Understanding solar fluctuations also helps place Sun among other stars in terms their brightness patterns and set detectability limits for terrestrial exo-planets. Aims. One most successful widely used SATIRE-S. It uses spectra magnetic features surrounding quiet computed with ATLAS9 synthesis code under assumption Local Thermodynamic Equilibrium (LTE). SATIRE-S has been at forefront...
How global faculae and network coverage relates to that of sunspots is relevant the brightness variations Sun Sun-like stars. We extend earlier studies found facular-to-sunspot-area ratio diminishes with total sunspot coverage. Chromospheric indices magnetic flux enclosed in faculae, referred here as 'facular indices', are modulated by amount facular present. probed relationship between various through an empirical model takes into account how active regions evolve. This was incorporated a...
The Sun is the main energy source to Earth, and understanding its variability of direct relevance climate studies. Measurements total solar irradiance exist since 1978, but this too short compared climate-relevant time scales. Coming from a number different instruments, these measurements require cross-calibration, which not straightforward, thus several composite records have been created. All them suggest marginally decreasing trend 1996. Most composites also feature weak decrease over...
We aim to gain insight into the effect of network and faculae on solar irradiance from their apparent intensity. Taking full-disc observations Solar Dynamics Observatory, we examined intensity contrast in continuum core Fe I 6173 {\AA} line 1700 {\AA}, including variation with magnetic flux density, distance disc centre, nearby fields, time. The brightness is believed be suppressed by fields its convection. difference between quiet-Sun active region faculae, noted various studies, arises...