Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions
The Earth Radiation Budget (ERB), a measure of the difference between incoming solar irradiance and outgoing reflected and emitted radiant energy, is a fundamental property of Earth’s climate system. The Libera satellite mission will measure the ERB’s outgoing components to continue the long-term cl...
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MDPI AG
2025-07-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/17/15/2540 |
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| author | Mathew van den Heever Jake J. Gristey Peter Pilewskie |
| author_facet | Mathew van den Heever Jake J. Gristey Peter Pilewskie |
| author_sort | Mathew van den Heever |
| collection | DOAJ |
| description | The Earth Radiation Budget (ERB), a measure of the difference between incoming solar irradiance and outgoing reflected and emitted radiant energy, is a fundamental property of Earth’s climate system. The Libera satellite mission will measure the ERB’s outgoing components to continue the long-term climate data record established by NASA’s Clouds and the Earth’s Radiant Energy System (CERES) mission. In addition to ensuring data continuity, Libera will introduce a novel split-shortwave spectral channel to quantify the partitioning of the outgoing reflected solar component into visible and near-infrared sub-components. However, converting these split-shortwave radiances into the ERB-relevant irradiances requires the development of split-shortwave Angular Distribution Models (ADMs), which demand extensive angular sampling. Here, we show how Rotating Azimuthal Plane Scan (RAPS) parameters—specifically operational cadence and azimuthal scan rate—affect the observational coverage of a defined scene and angular space. Our results show that for a fixed number of azimuthal rotations, a relatively slow azimuthal scan rate of 0.5° per second, combined with more time spent in the RAPS observational mode, provides a more comprehensive sampling of the desired scene and angular space. We also show that operating the Libera instrument in RAPS mode at a cadence between every fifth day and every other day for the first year of space-based operations will provide sufficient scene and angular sampling for the observations to achieve radiance convergence for the scenes that comprise more than half of the expected Libera observations. Obtaining radiance convergence is necessary for accurate ADMs. |
| format | Article |
| id | doaj-art-51d5230fbca34a42a5f1fb10a9d79910 |
| institution | DOAJ |
| issn | 2072-4292 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Remote Sensing |
| spelling | doaj-art-51d5230fbca34a42a5f1fb10a9d799102025-08-20T03:04:43ZengMDPI AGRemote Sensing2072-42922025-07-011715254010.3390/rs17152540Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance ConversionsMathew van den Heever0Jake J. Gristey1Peter Pilewskie2Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO 80303, USALaboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO 80303, USALaboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO 80303, USAThe Earth Radiation Budget (ERB), a measure of the difference between incoming solar irradiance and outgoing reflected and emitted radiant energy, is a fundamental property of Earth’s climate system. The Libera satellite mission will measure the ERB’s outgoing components to continue the long-term climate data record established by NASA’s Clouds and the Earth’s Radiant Energy System (CERES) mission. In addition to ensuring data continuity, Libera will introduce a novel split-shortwave spectral channel to quantify the partitioning of the outgoing reflected solar component into visible and near-infrared sub-components. However, converting these split-shortwave radiances into the ERB-relevant irradiances requires the development of split-shortwave Angular Distribution Models (ADMs), which demand extensive angular sampling. Here, we show how Rotating Azimuthal Plane Scan (RAPS) parameters—specifically operational cadence and azimuthal scan rate—affect the observational coverage of a defined scene and angular space. Our results show that for a fixed number of azimuthal rotations, a relatively slow azimuthal scan rate of 0.5° per second, combined with more time spent in the RAPS observational mode, provides a more comprehensive sampling of the desired scene and angular space. We also show that operating the Libera instrument in RAPS mode at a cadence between every fifth day and every other day for the first year of space-based operations will provide sufficient scene and angular sampling for the observations to achieve radiance convergence for the scenes that comprise more than half of the expected Libera observations. Obtaining radiance convergence is necessary for accurate ADMs.https://www.mdpi.com/2072-4292/17/15/2540angular distribution modelrotational azimuth plane scanradianceirradiancesplit-shortwave |
| spellingShingle | Mathew van den Heever Jake J. Gristey Peter Pilewskie Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions Remote Sensing angular distribution model rotational azimuth plane scan radiance irradiance split-shortwave |
| title | Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions |
| title_full | Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions |
| title_fullStr | Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions |
| title_full_unstemmed | Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions |
| title_short | Optimizing the Sampling Strategy for Future Libera Radiance to Irradiance Conversions |
| title_sort | optimizing the sampling strategy for future libera radiance to irradiance conversions |
| topic | angular distribution model rotational azimuth plane scan radiance irradiance split-shortwave |
| url | https://www.mdpi.com/2072-4292/17/15/2540 |
| work_keys_str_mv | AT mathewvandenheever optimizingthesamplingstrategyforfutureliberaradiancetoirradianceconversions AT jakejgristey optimizingthesamplingstrategyforfutureliberaradiancetoirradianceconversions AT peterpilewskie optimizingthesamplingstrategyforfutureliberaradiancetoirradianceconversions |