Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations
This paper presents a simple radiative transfer model based on spectral invariant properties (SIP). The canopy structure parameters, including the leaf angle distribution and multi-angular clumping index, are explicitly described in the SIP model. The SIP model has been evaluated on its bidirectiona...
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doaj-681e997d88204b8b80a182862d8514092020-11-24T21:18:37ZengMDPI AGRemote Sensing2072-42922018-09-011010150810.3390/rs10101508rs10101508Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable EstimationsYelu Zeng0Baodong Xu1Gaofei Yin2Shengbiao Wu3Guoqing Hu4Kai Yan5Bin Yang6Wanjuan Song7Jing Li8Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305, USAState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, ChinaResearch Center for Digital Mountain and Remote Sensing Application, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, ChinaState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, ChinaSchool of Aeronautics and Astronautics, Purdue University, West Lafayette, IN 47907, USAState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, ChinaCollege of Electrical and Information Engineering, Hunan University, Changsha 410082, ChinaState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, ChinaState Key Laboratory of Remote Sensing Science, Jointly Sponsored by Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, ChinaThis paper presents a simple radiative transfer model based on spectral invariant properties (SIP). The canopy structure parameters, including the leaf angle distribution and multi-angular clumping index, are explicitly described in the SIP model. The SIP model has been evaluated on its bidirectional reflectance factor (BRF) in the angular space at the radiation transfer model intercomparison platform, and in the spectrum space by the PROSPECT+SAIL (PROSAIL) model. The simulations of BRF by SIP agreed well with the reference values in both the angular space and spectrum space, with a root-mean-square-error (RMSE) of 0.006. When compared with the widely-used Soil-Canopy Observation of Photochemistry and Energy fluxes (SCOPE) model on fPAR, the RMSE was 0.006 and the R2 was 0.99, which shows a high accuracy. This study also suggests the newly proposed vegetation index, the near-infrared (NIR) reflectance of vegetation (NIRv), was a good linear approximation of the canopy structure parameter, the directional area scattering factor (DASF), with an R2 of 0.99. NIRv was not influenced much by the soil background contribution, but was sensitive to the leaf inclination angle. The sensitivity of NIRv to canopy structure and the robustness of NIRv to the soil background suggest NIRv is a promising index in future biophysical variable estimations with the support of the SIP model, especially for the Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) observations near the hot spot directions.http://www.mdpi.com/2072-4292/10/10/1508spectral invariantradiative transfercanopy structureleaf inclination anglehot spot |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yelu Zeng Baodong Xu Gaofei Yin Shengbiao Wu Guoqing Hu Kai Yan Bin Yang Wanjuan Song Jing Li |
spellingShingle |
Yelu Zeng Baodong Xu Gaofei Yin Shengbiao Wu Guoqing Hu Kai Yan Bin Yang Wanjuan Song Jing Li Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations Remote Sensing spectral invariant radiative transfer canopy structure leaf inclination angle hot spot |
author_facet |
Yelu Zeng Baodong Xu Gaofei Yin Shengbiao Wu Guoqing Hu Kai Yan Bin Yang Wanjuan Song Jing Li |
author_sort |
Yelu Zeng |
title |
Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations |
title_short |
Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations |
title_full |
Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations |
title_fullStr |
Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations |
title_full_unstemmed |
Spectral Invariant Provides a Practical Modeling Approach for Future Biophysical Variable Estimations |
title_sort |
spectral invariant provides a practical modeling approach for future biophysical variable estimations |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2018-09-01 |
description |
This paper presents a simple radiative transfer model based on spectral invariant properties (SIP). The canopy structure parameters, including the leaf angle distribution and multi-angular clumping index, are explicitly described in the SIP model. The SIP model has been evaluated on its bidirectional reflectance factor (BRF) in the angular space at the radiation transfer model intercomparison platform, and in the spectrum space by the PROSPECT+SAIL (PROSAIL) model. The simulations of BRF by SIP agreed well with the reference values in both the angular space and spectrum space, with a root-mean-square-error (RMSE) of 0.006. When compared with the widely-used Soil-Canopy Observation of Photochemistry and Energy fluxes (SCOPE) model on fPAR, the RMSE was 0.006 and the R2 was 0.99, which shows a high accuracy. This study also suggests the newly proposed vegetation index, the near-infrared (NIR) reflectance of vegetation (NIRv), was a good linear approximation of the canopy structure parameter, the directional area scattering factor (DASF), with an R2 of 0.99. NIRv was not influenced much by the soil background contribution, but was sensitive to the leaf inclination angle. The sensitivity of NIRv to canopy structure and the robustness of NIRv to the soil background suggest NIRv is a promising index in future biophysical variable estimations with the support of the SIP model, especially for the Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) observations near the hot spot directions. |
topic |
spectral invariant radiative transfer canopy structure leaf inclination angle hot spot |
url |
http://www.mdpi.com/2072-4292/10/10/1508 |
work_keys_str_mv |
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1726008290032222208 |