Calibration of the absorptance cavities for the spaceflight solar radiometer TIM

Heuerman, Karl; Harber, D.; Ebbets, Allison; Kopp, Greg; Logan, Lucy

doi:10.1117/12.679668

Cited by 2 publications

(5 citation statements)

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“…The Solar Orbiter (SO) mission, launched in 2020, combines in situ measurements in the Heliosphere or multiple telescope channels for remote imaging of the Sun and its atmosphere. This mission shows a unique short distance (minimum perihelion of 0.28 AU) and an orbit out of the ecliptic plane (18 °and 30 °helio-latitude during nominal and extended mission phase, respectively) [76]. Even without a TSI radiometer, the expected data from SO will contribute to the heliosphere investigation and the solar activity changes over time [99].…”

Section: Discussion and Perspectives About Total Solar Irradiance Obs...mentioning

confidence: 98%

“…Over the last decades, there has been significant improvement in the design and calibration of absolute radiometers but still requires improvements, including tracking degradation for appropriate in-flight correction. In addition, the observation instabilities can raise speculation about whether the interminima TSI decrease from 1996 to 2008 is authentic or instrumental and model limitation [76].…”

Section: Discussion and Perspectives About Total Solar Irradiance Obs...mentioning

confidence: 99%

“…The cavity reflectance value made at 633 nm for TIM and CLARA are in the order of 60 ppm [76] and 2000 ppm [75], but the length of the cavities is 6.34 cm [73] and 1.88 cm [75], respectively. The increase of the cavity size results in absorption enhancement.…”

Section: Background and Operating Principlementioning

confidence: 98%

“…ACRIM prevented heat transfer to the environment by aluminized Kapton shields [74], while TIM, CLARA, and JTSIM plated gold outside to minimize the radiative losses. The typical geometries consist of a cone plus a cylinder [76], just the cylinder [77], cone, or inverted cone [78]. The measured reflectivity depends on the size and absorbing material.…”

Section: Background and Operating Principlementioning

confidence: 99%

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Solar Irradiance Variability Monitor for the Galileo Solar Space Telescope Mission: Concept and Challenges

et al. 2022

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Long and reliable total solar irradiance (TSI) time series is one of the essential parameters for understanding solar contributions to climate change. The minor fluctuations of TSI in long timescales could impact the energy balance. Despite the improvement of accurate measurements provided by the instruments, at the time, long-term TSI variability and its effects had not been established. The space-borne radiometer era provided observations in short timescales from minutes to years. Therefore, this study presents an overview of irradiance observations, highlighting the importance of following its variability in different time scales. In this context, the Galileo Solar Space Telescope that has been developed by the Institute for Space Research (INPE), Brazil, includes the Irradiance Monitor Module with a radiometer cavity like the classical design and a next-generation compact radiometer.

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Section: Discussion and Perspectives About Total Solar Irradiance Obs...mentioning

confidence: 98%

Section: Discussion and Perspectives About Total Solar Irradiance Obs...mentioning

confidence: 99%

Section: Background and Operating Principlementioning

confidence: 98%

Section: Background and Operating Principlementioning

confidence: 99%

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Solar Irradiance Variability Monitor for the Galileo Solar Space Telescope Mission: Concept and Challenges

et al. 2022

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“…The cavity spectral absorptivity was quantified using the LASP cavity characterization facility for TSI radiometer cone cavity measurements [29]. These characterizations are performed by direct cavity reflectance measurements (spatially averaged) from the UV through the near-IR range.…”

Section: Cavity Reflectance Uncertaintymentioning

confidence: 99%

SI-traceable Spectral Irradiance Radiometric Characterization and Absolute Calibration of the TSIS-1 Spectral Irradiance Monitor (SIM)

et al. 2020

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The current implementation for continuous, long-term solar spectral irradiance (SSI) monitoring is the Total and Spectral Solar Irradiance Sensor (TSIS-1) Spectral Irradiance Monitor (SIM) that began operations from the International Space Station (ISS) in March 2018 and nominally provides an SSI spectrum every 12 h. Advances in both instrument design and spectral irradiance calibration techniques have resulted in the TSIS-1 SIM achieving higher absolute accuracy than its predecessor instrument in the wavelength range (200–2400 nm). A comprehensive detector-based Spectral Radiometer Facility (SRF) was developed in collaboration with the US National Institute for Standards and Technology (NIST) to ensure the ties to spectral SI standards in power and irradiance. Traceability is achieved via direct laser calibration of a focal plane electrical substitution radiometer (ESR) against a cryogenic radiometer in power and also irradiance responsivity via calibrated apertures. The SIM accuracy definition followed an absolute sensor approach based on a full radiometric measurement equation where component-level performance characterizations and calibrations were quantified with an associated uncertainty error budget and verified by independent measurements for each parameter. Unit-level characterizations were completed over the full operational envelope of external driving factors (e.g., pointing and temperature ranges) and were allowed for the independent parameterization of sub-assembly performance for expected operating conditions. Validation and final instrument end-to-end absolute calibration in the Laboratory for Atmospheric and Space Physics (LASP)-SRF achieved low combined standard uncertainty (uc < 0.25%, k = 1) in spectral irradiance.

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Calibration of the absorptance cavities for the spaceflight solar radiometer TIM

Cited by 2 publications

References 0 publications

Solar Irradiance Variability Monitor for the Galileo Solar Space Telescope Mission: Concept and Challenges

Solar Irradiance Variability Monitor for the Galileo Solar Space Telescope Mission: Concept and Challenges

SI-traceable Spectral Irradiance Radiometric Characterization and Absolute Calibration of the TSIS-1 Spectral Irradiance Monitor (SIM)

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