Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles
Leaf reflectance and transmittance spectra are essential information in many applications such as developing remote sensing methods, computing shortwave energy balance (albedo) of forest canopies, and monitoring health or stress of trees. Measurement of coniferous needle spectra has usually been car...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Finnish Society of Forest Science
2020-03-01
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| Series: | Silva Fennica |
| Subjects: |
| _version_ | 1818477146237042688 |
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| author | Aarne Hovi Matti Mõttus Jussi Juola Farshid Manoocheri Erkki Ikonen Miina Rautiainen |
| author_facet | Aarne Hovi Matti Mõttus Jussi Juola Farshid Manoocheri Erkki Ikonen Miina Rautiainen |
| author_sort | Aarne Hovi |
| collection | DOAJ |
| description | Leaf reflectance and transmittance spectra are essential information in many applications such as developing remote sensing methods, computing shortwave energy balance (albedo) of forest canopies, and monitoring health or stress of trees. Measurement of coniferous needle spectra has usually been carried out with single integrating spheres, which has involved a lot of tedious manual work. A small double integrating sphere would make the measurements considerably faster, because of its ease of operation and small sample sizes required. Here we applied a compact double integrating sphere setup, used previously for measurement of broad leaves, for measurement of coniferous needles. Test measurements with the double integrating sphere showed relative underestimation of needle albedo by 5–39% compared to a well-established single integrating sphere setup. A small part of the bias can be explained by the bias of the single sphere. Yet the observed bias is quite significant if absolute accuracy of measurements is required. For relative measurements, e.g. for monitoring development of needle spectra over time, the double sphere system provides notable improvement. Furthermore, it might be possible to reduce the bias by building an optimized measurement setup that minimizes absorption losses in the sample port. Our study indicates that double spheres, after some technical improvement, may provide a new and fast way to collect extensive spectral libraries of tree species. |
| first_indexed | 2024-12-10T09:34:27Z |
| format | Article |
| id | doaj.art-10363c0ced7b40ea9e28f86f97e85caa |
| institution | Directory Open Access Journal |
| issn | 2242-4075 2242-4075 |
| language | English |
| last_indexed | 2024-12-10T09:34:27Z |
| publishDate | 2020-03-01 |
| publisher | Finnish Society of Forest Science |
| record_format | Article |
| series | Silva Fennica |
| spelling | doaj.art-10363c0ced7b40ea9e28f86f97e85caa2022-12-22T01:54:14ZengFinnish Society of Forest ScienceSilva Fennica2242-40752242-40752020-03-0154210.14214/sf.10270Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needlesAarne Hovi0https://orcid.org/0000-0002-2745-1966Matti Mõttus1https://orcid.org/0000-0002-2745-1966Jussi Juola2Farshid Manoocheri3https://orcid.org/0000-0003-3935-3930Erkki Ikonen4https://orcid.org/0000-0001-6444-5330Miina Rautiainen5https://orcid.org/0000-0002-6568-3258Aalto University, School of Engineering, Department of Built Environment, P.O.Box 14100, FI-00760 Aalto, FinlandVTT Technical Research Centre Finland, P.O. Box 1000, FI-02044 VTT, FinlandAalto University, School of Engineering, Department of Built Environment, P.O.Box 14100, FI-00760 Aalto, FinlandAalto University, School of Electrical Engineering, Metrology Research Institute, Maarintie 8, FI-02150 Espoo, FinlandVTT Technical Research Centre Finland, P.O. Box 1000, FI-02044 VTT, Finland; Aalto University, School of Electrical Engineering, Metrology Research Institute, Maarintie 8, FI-02150 Espoo, FinlandAalto University, School of Engineering, Department of Built Environment, P.O.Box 14100, FI-00760 Aalto, Finland; Aalto University, School of Electrical Engineering, Department of Electronics and Nanoengineering, P.O. Box 15500, FI-00760 Aalto, FinlandLeaf reflectance and transmittance spectra are essential information in many applications such as developing remote sensing methods, computing shortwave energy balance (albedo) of forest canopies, and monitoring health or stress of trees. Measurement of coniferous needle spectra has usually been carried out with single integrating spheres, which has involved a lot of tedious manual work. A small double integrating sphere would make the measurements considerably faster, because of its ease of operation and small sample sizes required. Here we applied a compact double integrating sphere setup, used previously for measurement of broad leaves, for measurement of coniferous needles. Test measurements with the double integrating sphere showed relative underestimation of needle albedo by 5–39% compared to a well-established single integrating sphere setup. A small part of the bias can be explained by the bias of the single sphere. Yet the observed bias is quite significant if absolute accuracy of measurements is required. For relative measurements, e.g. for monitoring development of needle spectra over time, the double sphere system provides notable improvement. Furthermore, it might be possible to reduce the bias by building an optimized measurement setup that minimizes absorption losses in the sample port. Our study indicates that double spheres, after some technical improvement, may provide a new and fast way to collect extensive spectral libraries of tree species.albedoneedle carrierreflectancespectratransmittancevegetation |
| spellingShingle | Aarne Hovi Matti Mõttus Jussi Juola Farshid Manoocheri Erkki Ikonen Miina Rautiainen Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles Silva Fennica albedo needle carrier reflectance spectra transmittance vegetation |
| title | Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles |
| title_full | Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles |
| title_fullStr | Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles |
| title_full_unstemmed | Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles |
| title_short | Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles |
| title_sort | evaluating the performance of a double integrating sphere in measurement of reflectance transmittance and albedo of coniferous needles |
| topic | albedo needle carrier reflectance spectra transmittance vegetation |
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