151 citations · 972 across the 25 of their papers we have counts for
25 papers
Revisiting the SATIRE-S irradiance reconstruction: Heritage of Mt Wilson magnetograms and Ca II K observations
Theodosios Chatzistergos, Natalie A. Krivova, Sami K. Solanki +1
Accurate information on long-term variations in solar irradiance, important for understanding the solar influence on Earth's climate, cannot be derived from direct irradiance measu…
The variation in the response of solar full-disc magnetographs
K. L. Yeo, S. K. Solanki, N. A. Krivova
We compared magnetograms from the KPVT/SPM, SoHO/MDI, SOLIS/VSM, and SDO/HMI with the aim of probing the effect on measured solar magnetism of the variation in instrument response…
Reconstruction of total solar irradiance variability as simultaneously apparent from Solar Orbiter and Solar Dynamics Observatory
K. L. Yeo, N. A. Krivova, S. K. Solanki +42
Solar irradiance variability has been monitored almost exclusively from the Earth's perspective. {We present a method to combine the unprecedented observations of the photospheric…
Spectral variability of photospheric radiation due to faculae II: Facular contrasts for cool main-sequence stars
Charlotte M. Norris, Yvonne C. Unruh, Veronika Witzke +5
Magnetic features on the surface of stars, such as spots and faculae, cause stellar spectral variability on time-scales of days and longer. For stars other than the Sun, the spectr…
Long-term changes in solar activity and irradiance
Theodosios Chatzistergos, Natalie A. Krivova, Kok Leng Yeo
The Sun is the main energy source to Earth, and understanding its variability is of direct relevance to climate studies. Measurements of total solar irradiance exist since 1978, bu…
The relationship between bipolar magnetic regions and their sunspots
K. L. Yeo, S. K. Solanki, N. A. Krivova +1
The relationship between bipolar magnetic regions (BMRs) and their sunspots is an important property of the solar magnetic field, but it is not well constrained. One consequence is…
Reconstructing solar irradiance from historical Ca II K observations. I. Method and its validation
Theodosios Chatzistergos, Natalie A. Krivova, Ilaria Ermolli +5
Knowledge of solar irradiance variability is critical to Earth's climate models and understanding the solar influence on Earth's climate. Direct solar irradiance measurements are o…
Modeling stellar Ca II H & K emission variations. I. Effect of inclination on the S-index
K. Sowmya, A. I. Shapiro, V. Witzke +5
The emission in the near ultraviolet Ca II H & K lines is modulated by stellar magnetic activity. Although this emission, quantified via the S-index, has been serving as a prime pr…
Intensity contrast of solar network and faculae -- II. Implications for solar irradiance modelling
K. L. Yeo, N. A. Krivova
We aim to gain insight into the effect of network and faculae on solar irradiance from their apparent intensity. Taking full-disc observations from the Solar Dynamics Observatory,…
The Dimmest State of the Sun
K. L. Yeo, S. K. Solanki, N. A. Krivova +5
How the solar electromagnetic energy entering the Earth's atmosphere varied since pre-industrial times is an important consideration in the climate change debate. Detrimental to th…
How faculae and network relate to sunspots, and the implications for solar and stellar brightness variations
K. L. Yeo, S. K. Solanki, N. A. Krivova
How global faculae and network coverage relates to that of sunspots is relevant to the brightness variations of the Sun and Sun-like stars. We extend earlier studies that found the…
Readdressing the UV solar variability with SATIRE-S: non-LTE effects
R. V. Tagirov, A. I. Shapiro, N. A. Krivova +3
Context. Solar spectral irradiance (SSI) variability is one of the key inputs to models of the Earth's climate. Understanding solar irradiance fluctuations also helps to place the…
Recovering the unsigned photospheric magnetic field from Ca II K observations
Theodosios Chatzistergos, Ilaria Ermolli, Sami K. Solanki +3
We reassess the relationship between the photospheric magnetic field strength and the Ca II K intensity for a variety of surface features as a function of the position on the disc…
The nature of solar brightness variations
A. I. Shapiro, S. K. Solanki, N. A. Krivova +3
The solar brightness varies on timescales from minutes to decades. Determining the sources of such variations, often referred to as solar noise, is of importance for multiple reaso…
Solar Irradiance Variability is Caused by the Magnetic Activity on the Solar Surface
K. L. Yeo, S. K. Solanki, C. M. Norris +3
The variation in the radiative output of the Sun, described in terms of solar irradiance, is important to climatology. A common assumption is that solar irradiance variability is d…
Spectral variability of photospheric radiation due to faculae I: The Sun and Sun-like stars
Charlotte M. Norris, Benjamin Beeck, Yvonne C. Unruh +3
Context. Stellar spectral variability on timescales of a day and longer, arising from magnetic surface features such as dark spots and bright faculae, is an important noise source…
EMPIRE: A robust empirical reconstruction of solar irradiance variability
K. L. Yeo, N. A. Krivova, S. K. Solanki
We present a new empirical model of total and spectral solar irradiance (TSI and SSI) variability entitled EMPirical Irradiance REconstruction (EMPIRE). As with existing empirical…
Reconstruction of spectral solar irradiance since 1700 from simulated magnetograms
M. Dasi-Espuig, J. Jiang, N. A. Krivova +3
We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. T…
Are solar brightness variations faculae- or spot-dominated?
A. I. Shapiro, S. K. Solanki, N. A. Krivova +2
Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to surface magnetic…
UV solar irradiance in observations and the NRLSSI and SATIRE-S models
K. L. Yeo, W. T. Ball, N. A. Krivova +3
Total solar irradiance and UV spectral solar irradiance have been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aime…
Analysis and modeling of solar irradiance variations
K. L. Yeo
A prominent manifestation of the solar dynamo is the 11-year activity cycle, evident in indicators of solar activity, including solar irradiance. Although a relationship between so…
Reconstruction of total and spectral solar irradiance from 1974 to 2013 based on KPVT, SoHO/MDI and SDO/HMI observations
K. L. Yeo, N. A. Krivova, S. K. Solanki +1
Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. We present a reconstruction of daily solar irradiance…
Solar cycle variation in solar irradiance
K. L. Yeo, N. A. Krivova, S. K. Solanki
The correlation between solar irradiance and the 11-year solar activity cycle is evident in the body of measurements made from space, which extend over the past four decades. Model…
Point spread function of SDO/HMI and the effects of stray light correction on the apparent properties of solar surface phenomena
K. L. Yeo, A. Feller, S. K. Solanki +3
We present a PSF for SDO/HMI and discuss the effects of its removal on the apparent properties of solar surface phenomena in HMI data. The PSF was retrieved from observations of Ve…