Projects per year
Abstract
Leaf reflectance and transmittance spectra are urgently needed in interpretation of remote sensing data and modeling energy budgets of vegetation. The measurement methods should be fast to operate and preferably portable to enable quick collection of spectral databases and in situ measurements. At the same time, the collected spectra must be comparable across measurement campaigns. We compared three different methods for acquiring leaf reflectance and transmittance spectra. These were a single integrating sphere (ASD RTS-3ZC), a small double integrating sphere (Ocean Optics SpectroClip-TR), and a leaf clip (PP Systems UNI501 Mini Leaf Clip). With all methods, an ASD FieldSpec 4 spectrometer was used to measure white paper and tree leaves. Single and double integrating spheres showed comparable within-method variability in the measurements. Variability with leaf clip was slightly higher. The systematic difference in mean reflectance spectra between single and double integrating spheres was only minor (average relative difference of 1%), whereas a large difference (14%) was observed in transmittance. Reflectance measured with leaf clip was on average 14% higher compared to single integrating sphere. The differences between methods influenced also spectral vegetation indices calculated from the spectra, particularly those that were designed to track small changes in spectra. Measurements with double integrating sphere were four, and with leaf clip six times as fast as with single integrating sphere, if slightly reduced signal level (integration time reduced from optimum) was allowed for the double integrating sphere. Thus, these methods are fast alternatives to a conventional single integrating sphere. However, because the differences between methods depended on the measured target and wavelength, care must be taken when comparing the leaf spectra acquired with different methods.
Original language | English |
---|---|
Article number | 25 |
Number of pages | 19 |
Journal | Remote Sensing |
Volume | 10 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jan 2018 |
MoE publication type | A1 Journal article-refereed |
Keywords
- spectroscopy
- integrating sphere
- leaf clip
- contact probe
- leaf optical properties
- reflectance
- transmittance
- albedo
Fingerprint
Dive into the research topics of 'Evaluation of Accuracy and Practical Applicability of Methods for Measuring Leaf Reflectance and Transmittance Spectra'. Together they form a unique fingerprint.Projects
- 1 Finished
-
BOREALITY: Seasonal dynamics of the boreal region from space: connecting forest albedo to structure and productivity throughout the phenological cycle
Hovi, A. (Project Member), Rautiainen, M. (Principal investigator), Majasalmi, T. (Project Member), Juola, J. (Project Member) & Palviainen, P. (Project Member)
01/09/2015 → 31/12/2019
Project: Academy of Finland: Other research funding
Equipment
-
i3 – Industry Innovation Infrastructure
Sainio, P. (Manager)
School of EngineeringFacility/equipment: Facility
-
Spectral lab (i3)
Rautiainen, M. (Manager)
Department of Built EnvironmentFacility/equipment: Facility