ST1.5 | Advances in Solar Irradiance and Earth Radiation Budget Measurements and Modelling
Advances in Solar Irradiance and Earth Radiation Budget Measurements and Modelling
Co-organized by CL5
Convener: Margit Haberreiter | Co-convener: Ping Zhu
| Tue, 25 Apr, 16:15–18:00 (CEST)
Room M2
Posters on site
| Attendance Wed, 26 Apr, 08:30–10:15 (CEST)
Hall X4
Orals |
Tue, 16:15
Wed, 08:30
Solar Irradiance is the key energy input to Earth. A positive Earth Energy Imbalance (EEI) is the energy, which is continuously stored by the Earth and will ultimately be released to the atmosphere, causing global warming. In order to determine its exact value both the Total Solar Irradiance (TSI) and the Top of the Atmosphere (ToA) Outgoing Radiation (TOR) need to be measured with unprecedented accuracy and precision. This calls for improved instrument technologies as well as a traceable calibration chain of the space instrumentation. In this session we invite contributions on both the measurement and modeling of total and spectral solar irradiance and their effects on the Earth's atmosphere and climate, as well as latest measurements and modelling efforts to determine the Earth's outgoing radiation and the energy storage in the Earth's system.

Orals: Tue, 25 Apr | Room M2

Chairperson: Margit Haberreiter
Virtual presentation
Maria Z. Hakuba, Peter Pilewskie, and Graeme Stephens and the Libera Science Team

Libera, NASA’s first Earth Venture Continuity Mission, is in preparation to provide seamless continuity to current Earth outgoing radiance measurements conducted and processed by the Clouds and Earth’s Radiant Energy System (CERES) project. Leveraging advanced detector technologies, Libera will measure the broadband total, longwave, and shortwave radiances akin to CERES and achieve radiometric uncertainty of approximately 0.2%. Beyond the crucial radiation budget continuity goal, Libera will carry a fourth radiometer in the shortwave near-infrared to advance our understanding of shortwave energy deposition in the climate system, such as related to the characterization of processes relevant for shortwave absorption, climate feedbacks, and Earth’s albedo variability with added insight into hemispheric albedo symmetry given the hemispheric differences in ocean, continent and cloud distributions. We use global model simulations and radiative transfer calculations as proxies for Libera’s future data record to demonstrate applications of the shortwave sub-band knowledge in climate science. Although Libera’s absolute accuracy is unprecedented, it is still insufficient to adequately close Earth’s energy budget. We will therefore discuss current and future avenues to indirectly and directly measure EEI from space. The latter is potentially feasible through sensing radiation pressure-induced accelerations acting on near-spherical spacecrafts, which under optimal conditions, are directly proportional to the net radiative flux experienced at the satellite’s location. This approach has been considered in the past, and the feasibility to achieve a measurement accuracy within 0.3 Wm-2 is currently under investigation. 


How to cite: Hakuba, M. Z., Pilewskie, P., and Stephens, G. and the Libera Science Team: On the future of Earth radiation and energy imbalance measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10751,, 2023.

On-site presentation
Thorsten Fehr, Nigel Fox, Andrea Marini, and John Remedios

TRUTHS (Traceable Radiometry Underpinning Terrestrial- and Helio-Studies) is an operational climate mission, aiming to enhance up to an order-of-magnitude our ability to estimate the Earth radiation budget through direct measurements of spectrally resolved solar reflected Earth radiances and Sun irradiances becoming a ‘gold standard’ reference in support of climate emergency research and operational applications. It aims to establish a “metrology laboratory in space” by creating a fiducial, SI-traceable reference data set to cross-calibrate other sensors and improve the quality of their data.

TRUTHS main objective is to establish a reference baseline measurement (benchmark) of the state of the planet, against which past and future observations can be compared, in order to:

  • allow climate model improvements and forecast testing, and
  • provide observational evidence of climate change, including mitigation strategies in the shortest time possible.

TRUTHS will primarily measure the incoming and outgoing energy from the climate system with an accuracy needed to detect climate trends in the shortest possible time.

The datasets needed to meet this objective have many additional applications, such as:

  • SI traceable measurements of the incoming and reflected solar spectrum, to address direct science questions.
  • Operational products for removing radiometric biases in other satellite instruments by cross-calibration with TRUTHS data, improving accuracy and enabling inter-operability including improvement of retrieval algorithms.
  • Transferring radiometric reference values to existing Cal/Val infrastructure, e.g. RadCalNet, Pseudo-Invariant Calibration sites, In-situ ocean colour reference observations; selected surface reflectance test-sites (fluxnet ..), both nadir and multi-angular; to the Moon.

The mission comprises an “agile” satellite capable to point and image the Earth, the Moon and the Sun in a polar orbit hosting the Hyperspectral Imaging Spectrometer (HIS) capable to provide an accurate, continuously calibrated, dataset of spectrally resolved solar and lunar irradiance and Top of Atmosphere (ToA) Earth-reflected radiance in the near-UV/Visible/NIR/SWIR (320 nm to 2400 nm) waveband with a spectral sampling between 2 and 6 nm and a spatial sampling of 50 m. The payload utilises a novel SI traceable on-board calibration system, the Cryogenic Solar Absolute Radiometer (CSAR), as part of an innovative On-Board Calibration System (OBCS), allowing the HIS observations to achieve its unprecedented in-space accuracy, targeting an expanded radiometric uncertainty tied to international SI standards of 0.3% (k=2).

TRUTHS is implemented by the European Space Agency (ESA) as a UK led Earth Watch mission in collaboration with Switzerland, Czech Republic, Greece, Romania and Spain. The mission was conceived by the UK national metrology institute, NPL, in response to challenges highlighted by the worlds space agencies, through bodies such as CEOS, in relation to interoperability and accuracy. The mission is being developed by an industrial consortium led by Airbus Defence and Space UK.

The TRUTHS mission targets a launch in 2030 with a minimal life-time of 5 years, and design goal to reach 8 years, of in-orbit operations. It will become part of a future fleet of SI-Traceable Satellites (SITSATs) currently being developed by different space agencies, including CLARREO-Pathfinder (NASA) and CSRB (CMA), and together with FORUM (ESA) and IASI-NG (EUMETSAT) will provide spectrally resolved Earth radiance information from the UV to the Far-Infrared in the coming decade.

How to cite: Fehr, T., Fox, N., Marini, A., and Remedios, J.: Traceable Radiometry Underpinning Terrestrial- and Helio- Studies (TRUTHS) – A ‘gold standard’ imaging spectrometer in space to support climate emergency reseaerch, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12399,, 2023.

On-site presentation
Manal Yasmine Boudjella, Ahmed Hafid Belbachir, Samy Anis Amine Dib, and Mustapha Meftah

Monitoring accurately the amount of the incoming solar radiation reaching the ground surface and the outgoing radiation at the top of the atmosphere (TOA) is crucial for quantifying the earth's energy budget as well as for understanding and modelling the climate system and its evolution. In the present investigation, we explore the use of the Geant4 Monte Carlo toolkit and a new reference spectrum SOLAR/SOLSPEC [1] to develop a new model to estimate the spectral distribution of Top of Atmosphere Outgoing Radiation (TOR). The system is implemented in Geant4, a toolkit [2] that simulates the passage of particles through matter. SOLAR-ISS is a high resolution solar spectrum with a mean absolute uncertainty of 1.26% at 1σ. The TOR is estimated for a clear atmosphere and at different air mass (AM). For quality analysis, the performance of this model is examined and evaluated by comparing Geant4 simulation results with those of the DISORT code, where the relative mean difference is less than 7.29% overall the spectral domain from 280 to 3000 nm for a well defined case. The characteristics, such as transmittance and reflectance, etc., of the present and previous results will be analysed and compared to evaluate the performance of Geant4. We can upgrade the current tools with more powerful, efficient, and accurate prototyping. Furthermore, We will consider the design of a graphical user interface for the creation of the simulation input file, this utility will serve as a guideline that helps the user to run a simulation.

How to cite: Boudjella, M. Y., Belbachir, A. H., Dib, S. A. A., and Meftah, M.: A new approach to determine the Top of Atmosphere earth Outgoing Radiation using the Geant4 toolkit, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7190,, 2023.

On-site presentation
Maksym Vasiuta, Lauri Tuppi, Antti Penttilä, Karri Muinonen, and Heikki Järvinen

The Deep Space Climate Observatory (DSCOVR) is located near the Lagrangian L1 point of the Earth. Their EPIC images indicate exceptionally large values of the Earth's planetary albedo in December 2020, having daily average surged above 0.320 for consecutive three weeks. Independent evaluation of the Earth’s albedo using a numerical weather prediction model (OpenIFS of ECMWF) suggests that this is an over-estimate. Given the difference between satellite-based and model-based albedo estimates, the reconstructed from images top-of-atmosphere short-wave radiosity is over-estimated. We suggest the discrepancy is explained by a weakness of short-wave angular distribution models (ADMs) based on Clouds and the Earth's Radiant Energy System’s The Tropical Rainfall Measuring Mission (CERES/TRMM) in full back-scattering geometry. This conclusion is supported by disk-integrated short-wave anisotropy factors in December 2020, estimated using CERES ADMs, being lower than measured by NIST Advanced Radiometer (NISTAR).

How to cite: Vasiuta, M., Tuppi, L., Penttilä, A., Muinonen, K., and Järvinen, H.: Validation of DSCOVR-based albedo estimate using a weather model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15415,, 2023.

On-site presentation
Huizeng Liu, Ping Zhu, Shaopeng Huang, and Qingquan Li

Global climate change has aroused widespread concerns in society regarding the sustainable development of human beings. The Earth’s radiation budget (ERB) at the Top-of-Atmosphere (TOA) includes incident solar radiation, Earth-reflected shortwave radiation, and outgoing longwave radiation. The accuracy of the existing spaceborne instruments still cannot meet the measurement requirement of the Earth’s TOA shortwave and longwave radiation. In recent years, several novel observing platforms and sensors have been proposed for ERB. Hitherto, most of those concepts for ERB are still in the phase of design and development, and studies have been mainly carried out based on simulations. Simulating the sensor-measured signals of the proposed novel platforms, sensors or constellations could help to optimize the sensor parameters, determine the number of satellites in the constellation, explore their potentials in characterizing the ERB. The anisotropic factor, depicting the anisotropy of Earth’s radiation, is essential in the simulation. However, developing angular distribution models involves complex procedures of data preparation, processing, and modeling. This study, targeting at simplifying the procedure of simulating the signals of ERB sensors, proposed an approach of estimating the longwave anisotropic factors directly from the Earth’s radiative fluxes. The approach was implemented with CERES data and the neural network algorithm. Models were developed for 10 scene types based on Earth’s surface types. Results showed that the longwave anisotropic factors were accurately estimated with the correlation coefficient (r) varying between 0.85 and 0.98 and MAPE within 1.20% for the test dataset. With the estimated anisotropic factors, the sensor-measured radiances were accurately retrieved with r=1.00 and MAPE=0.53%. Therefore, the proposed approach is promising in accurate and efficient simulations of novel ERB platforms and sensors like the Moon-based Earth Radiation.

How to cite: Liu, H., Zhu, P., Huang, S., and Li, Q.: Estimating the Anisotropic Factor of Angular Distribution Models from Radiative Fluxes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4921,, 2023.

On-site presentation
Lionel Van Laeken, David Bolsée, Nuno Pereira, Mustapha Meftah, Alain Sarkissian, Luc Damé, Christophe Dufour, and the INSPIRE-SAT team

INSPIRE-SAT 7 is a French 2-Unit CubeSat primarily designed for Earth and Sun observations.  This mission is part of the International Satellite Program in Research and Education (INSPIRE). This satellite will be deployed in Low Earth Orbit (LEO) in 2023 as the first step of the so-called ‘Terra-F’ constellation that will provide spatio-temporal resolution for Earth Energy Imbalance (EEI) measurements.

This new scientific and technological pathfinder CubeSat mission (INSPIRE-SAT 7) is equipped with various channels on all sides. Among them: the Total Solar Irradiance Sensor (TSIS) payload, the Ultra-Violet Sensor (UVS) using a new generation of solar blind detectors designed to monitor the integrated Solar Spectral Irradiance (SSI) in the Hertzberg continuum, and the Earth Radiative Sensor (ERS) payload, designed to measure some Earth’s Radiative budget (ERB) components such as the outgoing short and long wave radiation at the top-of-the atmosphere for climate change studies.

The Belgian Radiometry Characterization Laboratory (B.RCLab) of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB) is the partner responsible for the pre-flight absolute calibration and radiometric characterization of INSPIRE-SAT7 TSIS and UVS payloads.

In this work we will first describe the INSPIRE-SAT7 concept, design, scientific and operational objectives. We will then present B.RCLab facilities along with its radiometric characterization benches, including the absolute calibration capabilities and its traceability. Finally, the main results of the INSPIRE-SAT7 pre-flight calibration campaign, which took place in November 2022, will be presented. These results allowed to calculate the sensors on-orbit calibration coefficients that are crucial to perform traceable absolute EEI measurements. A radiometric comprehensive uncertainty budget will be presented along the sensors’ calibration coefficients.

How to cite: Van Laeken, L., Bolsée, D., Pereira, N., Meftah, M., Sarkissian, A., Damé, L., Dufour, C., and team, T. I.-S.: INSPIRE-SAT7: Pre-Flight radiometric validation and calibration of a miniaturized Earth’s Radiative Budget satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12185,, 2023.

On-site presentation
Lien Smeesters, Steven Dewitte, and Thorsten Mauritsen

Monitoring the Earth Radiation Budget (ERB) and in particular the Earth
Energy Imbalance (EEI), is of paramount importance for a predictive
understanding of global climate change.   We propose the new Earth
Climate Observatory (ECO) space mission concept for the monitoring of
the EEI.

The EEI is defined as the small difference between the two nearly equal
terms of the incoming solar radiation, and the outgoing terrestrial
radiation lost to space. Making a significant measurement of the EEI
from space is very challenging, and requires a differential measurement
with one single instrument of both the incoming solar radiation and the
outgoing terrestrial radiation. The instrument that allows such a
differential measurement is an improved wide field of view electrical
substitution cavity radiometer.

The wide field of view radiometer will observe the earth from limb to
limb. A single measurement footprint is a circle with a diameter around
6300 km. For the discrimination of cloudy and clear skies, a higher
spatial resolution is needed. This will be obtained from two wide field
of view cameras, a visible wide field of view camera for the
characterisation of the spatial distribution of the reflected solar
radiation, and a thermal infrared wide field of view camera for the
characterisation of the spatial distribution of the emitted thermal

How to cite: Smeesters, L., Dewitte, S., and Mauritsen, T.: The Earth Climate Observatory (ECO) space mission concept for themonitoring of the Earth Energy Imbalance (EEI), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12178,, 2023.

On-site presentation
Peng Zhang, Jin Qi, Xin Ye, Yu Huang, and Ping Zhu

Fengyun 3 series (FY-3) is the second generation polar orbiting meteorological satellite in China. There are 5 satellites have been launched since the first satellite FY-3A in 2008. The solar irradiance is one of important parameters to measure by FY-3 series. The instrument to measure the solar irradiance is called Solar Irradiance Monitor (SIM). The SIM was deployed on the orbit since FY-3A (morning orbit AM) in 2008 and FY-3B (afternoon orbit PM) in 2010. SIM was upgraded to SIM-II mounted on FY-3C (AM orbit) in 2013. The sensitivity, absolute accuracy and stability of the instrument has been improved with the more accurate control on the solar disk tracking system and instrument environment temperature maintaining system. The SIM-II together with the Solar Spectral Irradiation Monitor (SSIM) have been deployed on the orbit mounted on FY-3E (early-morning orbit EM) in 2021. This presentation overviews the FY program. The specification and performance of SIM, SIM-II and SSIM have been illustrated. The measured Total Solar Irradiance (TSI) product has been compared with the similar measurements on SOHO/VIRGO, SORCE, TSIS-1, etc. The future plan for the solar measurements in FY-3 series has been presented in the last part.

How to cite: Zhang, P., Qi, J., Ye, X., Huang, Y., and Zhu, P.: Fengyun Program and Solar Observation Activities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12518,, 2023.

On-site presentation
Martin Snow, William McClintock, Janet Machol, Frank Eparvier, and Don Woodraska

The GOES-R series spacecraft include a new operational measurement for GOES satellites, the Magnesium II (MgII) core-to-wing index.  This solar activity proxy has been measured at a daily cadence beginning in 1978.  It is widely used in solar spectral irradiance models such as the NRLSSI CDR (Coddington et al. 2016).  The C Chanel of the Extreme and Ultraviolet Spectrograph (EUVSC) on GOES 16 began making operational MgII index measurements at high cadence in early 2017.  There are currently three such instruments in orbit on GOES 16, 17, and 18 as part of the EXIS suite of solar irradiance instruments.  In the past, the MgII index was only measured a few times per day, but EXIS makes measurements at a 3-second cadence to monitor rapid changes in the Sun.

In this presentation, we will describe the available data product and how it compares with previous measurements.  On long timescales it can be used to extend the historical record, and on short timescales it reveals solar activity of interest to space weather practitioners.

How to cite: Snow, M., McClintock, W., Machol, J., Eparvier, F., and Woodraska, D.: GOES EUVS Magnesium II Index: The beginning of a new climate data record, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10082,, 2023.

Virtual presentation
Ilaria Ermolli and Theodosios Chatzistergos

Knowledge of solar irradiance variability is critical to Earth's climate models and understanding the solar influence on Earth's climate. Direct measurements of the Total Solar Irradiance (TSI) have only been available since 1978 from instruments onboard multiple missions. Different calibrations of the individual instruments make estimates of the possible long-term trend in the TSI still uncertain. Knowledge of the Solar Spectral Irradiance (SSI) is even more undetermined. Here we use the carefully reduced observations from the Rome Precision Solar Photometric Telescope (Rome/PSPT) and semi-empirical irradiance models to reconstruct solar irradiance variations over the period 1996-2022. Results are discussed with respect to direct measurements and existing composite reconstructions.

How to cite: Ermolli, I. and Chatzistergos, T.: Reconstructing solar irradiance over the period 1996-2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16293,, 2023.

Posters on site: Wed, 26 Apr, 08:30–10:15 | Hall X4

Chairpersons: Ping Zhu, Margit Haberreiter
Ping Zhu, Huizeng Liu, Mi Song, Shaopeng Huang, and Qingquan Li

The space environment simulation facilities are the key to any successful space experiments and missions. To characterize and validate the optical space instrument, Shenzhen university is started to design a large vacuum chamber with various integrated standard radiation sources, covering a wavelength range from UV to near-infrared. The large radiometry calibration facilities (LRCF) will be traced to standard scale factors such as those maintained by the World Radiation Center at the Physikalisch Meteorologisches Observatorium Davos, Switzerland. In this presentation, we will introduce the LRCF and the broadband radiometer developed for the moon-based earth observation system and how to use the LRCF to characterize the radiometer.

How to cite: Zhu, P., Liu, H., Song, M., Huang, S., and Li, Q.: The deep space environment simulation vacuum chamber and large radiometry calibration facilities at Shenzhen University, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4478,, 2023.

Ed Thiemann, Karl Heuerman, Andres Villani-Davila, and Erik Richard

The total solar irradiance (TSI) is Earth’s primary source of energy, and accurate knowledge of its value and variability is crucial for understanding Earth’s climate and variability. In order to continue the existing 44 year data record of TSI measurements from space, NASA is developing the Total and Spectral Irradiance Sensors (TSIS) -2 mission. TSIS-2 consists of the Total Irradiance Monitor (TIM) and Spectral Irradiance Monitor (SIM) on a free flyer satellite, with an anticipated launch in the latter half of 2024. The TSIS-2/TIM is the latest iteration of the TIM instrument, prior versions of which flew onboard the SORCE, TCTE and TSIS-1 missions, and a direct rebuild of the TSIS-1 instrument. We present the pre-flight ground calibration of the TSIS-2/TIM instrument and its uncertainties. A key difference between the calibrations of the TSIS-1 and TSIS-2 instruments is the use of a novel low noise ambient temperature radiometer for TSIS-2 that significantly reduces the uncertainty in validating the component level calibrations through an end-to-end measurement. We compare component level (e.g. aperture area, detector reflectance, etc.) measurements and uncertainties for TSIS-2 with those from TSIS-1, and focus on areas where the uncertainty analysis differs from that applied to TIM instruments on prior missions and the implications of these differences.

How to cite: Thiemann, E., Heuerman, K., Villani-Davila, A., and Richard, E.: The TSIS-2 TIM Instrument Pre-Flight Calibration and Uncertainty, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10290,, 2023.

Jean-philippe Montillet, Werner Schmutz, Wolfgang Finsterle, Greg Kopp, Silvio Koller, Daniel Pfiffner, Manfred Gyo, Ricco Soder, Matthias Gander, Lloyd Beeler, Patrick Langer, Marcel Spescha, Pascal Schlatter, Jakob Föller, Margit Haberreiter, Karl Heuerman, and Andrei Zukhov

The Project for On-Board Autonomy-3 (PROBA-3) is the fourth satellite technology development and demonstration precursor mission within ESA's GSTP (General Support Technology Program) series. The primary mission objective is to demonstrate the technologies required for formation flying of multiple spacecrafts. The PROBA-3 mission concept comprises two independent minisatellites in highly-elliptical Earth orbits in precise formation flying, close to one another with the ability to accurately control the attitude and separation of the two satellites. The mission launch is scheduled for end of 2023.

PROBA-3 mission consists of a coronograph spacecraft, hosting the coronograph APIICS, and the occulter spacecraft with the Digital Absolute RAdiometer (DARA).  The radiometer to record total solar irradiance is mounted on the front satellite pointing to the Sun. DARA is  developed and manufactured in Switzerland by the PMOD/WRC. We have done two pre-flight calibration campaigns: one at the World Radiation Center in Davos, Switzerland, and one at the Total Solar Irradiance (TSI) Radiometer Facility of the Laboratory for Atmospheric and Space Physics in Boulder Colorado, USA. We report on the results of the laboratory comparisons and discuss uncertainties of several instrument parameters, which are used to transform the raw measurements, which are voltage and current, into solar irradiance values. 

How to cite: Montillet, J., Schmutz, W., Finsterle, W., Kopp, G., Koller, S., Pfiffner, D., Gyo, M., Soder, R., Gander, M., Beeler, L., Langer, P., Spescha, M., Schlatter, P., Föller, J., Haberreiter, M., Heuerman, K., and Zukhov, A.: The DARA/PROBA-3 radiometer: results from the preflight calibration campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9007,, 2023.

Margit Haberreiter, Wolfgang Finsterle, Jean-Philippe Montillet, Manfred Gyo, Dany Pfiffner, Martin Mostad, Ivar Spydevold, Alex Beattie, Bo Andersen, and Werner Schmutz

The Earth Radiation Budget at the Top of the Atmosphere (ToA) governs the status of climate change on our planet. The ERB is the balance between the incoming Total Solar Irradiance (TSI) and total outgoing radiation at the ToA. If more energy is stored in the system the Earth Energy Imbalance is positive and the temperature in the system rises. The Compact Lightweight Absolute RAdiometer (CLARA) experiment onboard the Norwegian micro satellite NorSat-1 is an SI traceable radiometer with the primary science goal to measure TSI from space. Besides TSI, CLARA also measures the terrestrial Outgoing Longwave Radiation (OLR) at the ToA on the night side of Earth. We present the latest status of the data and degradation correction obtained with this SI-traceable radiometer and compare the CLARA TSI and OLR time series with other available observations and reanalysis data. The validation of these measurements is key to advance our capability to determine the Earth Energy Imbalance from space. 

How to cite: Haberreiter, M., Finsterle, W., Montillet, J.-P., Gyo, M., Pfiffner, D., Mostad, M., Spydevold, I., Beattie, A., Andersen, B., and Schmutz, W.: Total Solar Irradiance and Terrestrial Outgoing Longwave Radiation Measurements obtained with CLARA onboard NorSat-1, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7221,, 2023.

Hong Qiu and Jin Qi

Earth Radiation Budget (ERB) measurement is one of the main missions of Chinese second generation of polar orbiting meteorological satellites ---FengYun-3 (FY-3) series. There are two instruments, the Solar Irradiance Monitor(SIM) and the Earth Radiation Budget (ERB), on board FY-3 satellite to observe the earth incoming and reflected solar radiance and the emitted radiance.  The ERMs on FY-3/A/B/C observe the Earth atmosphere within a narrow scanning field of view (NFOV)and a wide non-scanning field of view (WFOV). For each field of view, the measurements are made from two broadband channels: a total waveband channel covering 0.2 – 50 μm and a Short Wave (SW) band covering 0.2 - 4.3 μm. Because the sudden degradation happened that the SW channel of NFOV has stopped working after 20 months for FY-3A and 8 months for FY-3B in orbit. The observation from ERM on FY-3C has been in good condition for 9 years  In this presentation the performance of ERMs calibration in orbit is evaluated with CERES from EOS/Aqua and GERB-3 from Meteosat. The ERM LW and SW unfiltered radiance produced with spectral correction based on atmospheric transfer modelling has a good consistence with the other data. The new ERM instrument(ERM-II), which has a broadband LW channel covering 5-50 μm besides the Total and SW channels with a NFOV scanning mode, will be launch in the coming 2023 and provide 8 years global ERB observation from next FY-3 morning satellite.

How to cite: Qiu, H. and Qi, J.: Earth Radiation Budget Measurements on Chinese FY-3 Series Polar Orbit Satellites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4590,, 2023.

Xin Ye, Ping Zhu, Jean-Philippe Montillet, Xiuqing Hu, Jinhua Wang, Dongjun Yang, Jin Qi, Wolfgang Finsterle, Peng Zhang, Wei Fang, Silvio Koller, Daniel Pfiffner, Baoqi Song, Zhitao Luo, Kai Wang, Margit Haberreiter, Duo Wu, and Werner Schmutz

The Fengyun 3E (FY3E) spacecraft was launched on the 4th of July 2021 at 23h 28min UTC according to CASC (China Aerospace Science and Technology Corp.) on a Long March 4C vehicle from JSLC (Jiuquan Space Launch Center) in China. The orbit is a sun-synchronous near-circular with an altitude of 800 km, and an inclination of 98.7 degrees. The nominal lifetime of the satellite is eight years. The JTSIM experiments belong to the solar activities monitoring package. The solar radiation is absorbed by the black-coated cavity and the induced different heat-flux between the primary and reference cavity is measured, and the electrically calibrated differential heat-flux is used to compute the solar irradiance. SIAR has three identical channels A, B, and C, and each channel has a different solar exposure time to study the instrument’s nonlinear drift due to degradation. DARA also has three cavity radiometers and electrical substitution radiometers (Channel A, Channel B, and Channel C). The difference is that they are aligned in a triangle. Compared to VIRGO/PMO6, DARA inverts the aperture geometry to eliminate stray light. DARA and SIAR absolute radiometers are not operating at the same time due to the different designs and measurement sequences. On August 18, 2021, both instruments successfully passed the first commission phase, and they started to observe the total solar irradiance since then.

How to cite: Ye, X., Zhu, P., Montillet, J.-P., Hu, X., Wang, J., Yang, D., Qi, J., Finsterle, W., Zhang, P., Fang, W., Koller, S., Pfiffner, D., Song, B., Luo, Z., Wang, K., Haberreiter, M., Wu, D., and Schmutz, W.: The first light from the joint total solar irradiance measurement experiment onboard the FY3-E meteorological satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17162,, 2023.

Jin Qi, Peng Zhang, Hong Qiu, Ling Sun, Xin Ye, Wei Fang, and Yu Huang

Fengyun-3E is an early-morning orbit meteorological satellite which provided more opportunity to observe solar activities and was launched on July 5, 2021. The total solar irradiance is measured by Solar Irradiance Monitor-II (SIM-II) which has been improved on degradation monitor compared to earlier Fengyun satellite. The spectral solar irradiance is observed by the new payload Solar Spectral Irradiance Monitor (SSIM) which could provide continuous spectra from 165nm~2400nm. The SSIM instrument has three wavebands: UV band from 165 nm to 320 nm, VIS band from 285 nm to 700 nm, NIR band from 650 nm to 2400 nm, with spectral resolution as 1nm, 1nm and 8nm, respectively. In this work, we will present the design of solar observation, instruments on-orbit performance and preliminary results of FY-3E solar measurement.

How to cite: Qi, J., Zhang, P., Qiu, H., Sun, L., Ye, X., Fang, W., and Huang, Y.: The TSI and SSI measurement from Fengyun-3E Satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13188,, 2023.

Steven Penton, Martin Snow, Stephane Beland, Woodraska Don, and Coddington Odele

The EXIS (Extreme ultraviolet and X-ray Irradiance Sensors) detectors on the GOES-R spacecraft (GOES-16, GOES-17 & GOES-18) use quad-diode Sun Positioning Sensors (SPS) to maintain precision pointing. The 4 Hz quad-diode signal is high-precision and we attempt to use this signal as a high-cadence proxy for Total Solar Irradiance (TSI) and use the MgII index + NRLSS2 models to predict high-cadence spectra. The quad-diode signal must be calibrated for spacecraft velocity (a 1AU correction), instrument temperature, and diode degradation with usage. In the 2nd year of this 3-year project, we report the progress of these calibrations and our efforts toward defining our TSI proxy and high-cadence spectral data products.

How to cite: Penton, S., Snow, M., Beland, S., Don, W., and Odele, C.: GHOTI: GOES-R High-cadence Operational Total Irradiance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10126,, 2023.

Stéphane Béland and Steven Penton

The Solar Radiation and Climate Experiment measured Total Solar Irradiance (TSI) 
and Solar Spectral Irradiance (SSI) from 2003 to 2020. The Solar Irradiance Monitor (SIM) 
instrument measured SSI from 200nm to 2400 nm on a daily basis. The current SORCE-SIM
instrument degradation correction uses a measurement equation derived from
accessible telemetry, the known instrument refraction geometry, inter-detector comparisons,
and inter-spectrometer comparisons. While the current degradation model captures much of the
long-term trending, some of the parameters were adjusted without well-defined physical

The degradation model used for SORCE-SIM is not unique. We're reporting on work to Explore New
Instrument degradation Models and Algorithms (ENIGMA) to address issues with the current
model and with the derived corrected irradiances. The development of enhanced SORCE-SIM
measurement equations permits the evaluation, and potential inclusion, of degradation
mechanisms not captured in the present model.

We present an initial updated degradation model which improves our ability to construct a 
composite irradiance time series in combination with TSIS-SIM, whose measurements overlap 
with SORCE for 2 years and has well-defined uncertainties. Combining the two datasets, allowed
the construction of a consistent composite irradiance time series from 2003-2023. 

How to cite: Béland, S. and Penton, S.: Exploring New Instrument deGradation Models and Algorithms (ENIGMA), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16858,, 2023.

Abdanour Irbah, Jean-Loup Bertaux, Franck Montmessin, Alexander Trokhimovskiy, Oleg Korablev, and Anna Fedorova

The ACS-NIR spectrometer on board the Trace Gas Orbiter (TGO) is currently used to probe the atmosphere of Mars. It is, however, capable of measuring the near-infrared solar spectrum in the 0.7-1.7 µm domain with high spectral resolution when pointed at the Sun and its line of sight is above the atmosphere of Mars i.e. with its Solar Occultation mode. Specific observations were therefore made during 10 months in order to construct the solar spectrum in this spectral domain. The observations consist in recording all the diffraction orders of ACS-NIR by continuously varying the frequency of its AOTF (Acousto-Optic Tunable Filters, a component used to separate the orders). We will first present how we have treated each order of diffraction to improve the solar spectrum on the 0.7-1.7 µm band by considering for this purpose off-center images attached to certain AOTF frequencies. This method makes it possible to avoid contamination between the successive diffraction orders but also to increase the detection of the solar lines at the ends of each order where the intensity is low due to the Blaze function. We will then show the final version of the solar spectrum that we obtain. It will be compared to the reference spectrum, which is that of Toon. We will finish by showing and discuss some results revealing new solar lines appearing in certain diffraction orders of the ACS-NIR spectrometer and which are not present in the corresponding parts of the reference solar spectrum. 

How to cite: Irbah, A., Bertaux, J.-L., Montmessin, F., Trokhimovskiy, A., Korablev, O., and Fedorova, A.: High-resolution solar spectrum obtained from TGO orbiting Mars reveals new solar lines in the 0.7-1.7 µm range, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9484,, 2023.

Isabela de Oliveira, Krishnamurthy Sowmya, Nina-Elizabeth Nèmec, and Laurent Gizon

Solar irradiance is the main source of energy input to the planets of the Solar System. The solar rotation and the evolution of active regions on the surface of the Sun are two of the sources of solar irradiance variability. Nèmec et al. (2020) showed that the variability of solar irradiance is dominated by one of these two sources depending on the timescale of interest. The solar rotation dominates the variability for periods between 4-5 days and the synodic solar rotation period (27.3 days), while the evolution of active regions dominate for the remaining timescales.

Usually, the irradiance measurements at Earth are extrapolated to estimate the irradiance at other planets and study the effect of solar irradiance on other planets' atmospheres (Thiemann et al., 2017). In this "lighthouse model", the irradiance source regions on the surface of the Sun are assumed to simply rotate with a Carrington sidereal period of 25.38 days. This means that the solar rotation is the only cause of variability of the irradiance in this model, and the evolution of active regions is neglected.

In this work, we develop a model to calculate the irradiance at other planets by accounting for the evolution of magnetic features. Our method follows the Spectral And Total Irradiance REconstruction (SATIRE; Fligge et al. 2000; Krivova et al. 2003) approach and works by Nèmec et al. (2020) and Sowmya et al. (2021). First, the Surface Flux Transport Model (SFTM; Cameron et al. 2010) is used to obtain the time-dependent surface distribution of magnetic features (faculae and spots). Then, the solar irradiance is calculated as the sum of the contributions from the quiet Sun (i.e., regions with no magnetic activity), faculae, and spots. 

Our method allows calculating the solar irradiance directly at a given position within the ecliptic, regardless of the position of the Earth. We compare our irradiance calculations with those of the extrapolation method. We find that taking the evolution of active regions into account improves the estimation of solar irradiance significantly, especially when it comes to wavelengths in the visible and infrared ranges. Therefore, we suggest that our method provides more accurate estimates of solar irradiance to be used as input in studies of planetary atmospheres.

We would like to note that our method of irradiance calculation is currently only statistical. We use the SFTM as we do not have information of the areas of the far-side of the Sun, which are needed in order to get the correct rotational variability. To determine real daily values of irradiance, we need to combine our calculations with methods of helioseismology, which is still a work in progress.

How to cite: de Oliveira, I., Sowmya, K., Nèmec, N.-E., and Gizon, L.: Solar irradiance estimation for planetary studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15701,, 2023.

Valentina Zharkova, Irina Vasilieva, and Elena Popova

The  long-term millennial oscillations of the baseline  solar background magnetic field (SBMF) and the ephemeris of  the Sun-Earth distances are compared with the oscillations of solar irradiance at the terrestrial biomass (Hallstatt's cycle).    

Based  the Sun-Earth distances derived from the current JPL ephemeris based on solar inertial motion and gravitational effects on the Sun by four large planets: Jupiter, Saturn, Neptune and Uranus we  demonstrate the S-E distance is reduced by 0.005 au in the millennium M1 600-1600 and 0.011 au in millennium M2 1600-2600. We show that variations of the Sun-Earth distances  are accountable for the increase of the solar irradiance by about $20-25$ $Wm^{-2}$ since 1700 that will continue to last until 2500. he decrease of the S-E distance per century in the current millennium follows the  rate of the terrestrial temperature increase reported since MM. We evaluate that this difference of the Sun-Earth distances caused by SIM  leads to the different magnitudes of solar irradiance deposited in the Northern and Southern hemispheres  in M2 with thee Northern hemisphere to obtain more radiation compared to the Southern one. These estimations show that in the next 600 years the Sun will continue moving towards the Earth  that will result in a further increase of solar irradiance and the baseline terrestrial temperature  in 2500-2600. These variations are expected to be over-imposed by a reduction of solar activity during two grand solar minima (GSMs) with a reduce terrestrial temperatures by 1C  to occur  in 2020-2053 and 2370-2415. 

How to cite: Zharkova, V., Vasilieva, I., and Popova, E.: Solar total radiation input and terrestrial temperature in the two millennia of 600-2600, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5900,, 2023.