scholarly journals Reflectance Properties of Hemiboreal Mixed Forest Canopies with Focus on Red Edge and Near Infrared Spectral Regions

2019 ◽  
Vol 11 (14) ◽  
pp. 1717 ◽  
Author(s):  
Lea Hallik ◽  
Andres Kuusk ◽  
Mait Lang ◽  
Joel Kuusk
Keyword(s):  
Spectral Resolution ◽  
Spectral Region ◽  
Inflection Point ◽  
Forest Canopy ◽  
Mixed Forest ◽  
Single Band ◽  
High Spectral Resolution ◽  
Mathematical Form ◽  
Fraunhofer Line ◽  
Red Edge

This study present the results of airborne top-of-canopy measurements of reflectance spectra in the spectral domain of 350–1050 nm over the hemiboreal mixed forest. We investigated spectral transformations that were originally designed for utilization at very different spectral resolutions. We found that the estimates of red edge inflection point by two methods—the linear four-point interpolation approach (S2REP) and searching the maximum of the first derivative spectrum ( D m a x ) according to the mathematical definition of red edge inflection point—were well related to each other but S2REP produced a continuously shifting location of red edge inflection point while D m a x resulted in a discrete variable with peak jumps between fixed locations around 717 nm and 727 nm for forest canopy (the third maximum at 700 nm appeared only in clearcut areas). We found that, with medium high spectral resolution (bandwidth 10 nm, spectral step 3.3 nm), the in-filling of the O 2 -A Fraunhofer line ( F a r e a ) was very strongly related to single band reflectance factor in NIR spectral region ( ρ = 0.91, p < 0.001) and not related to Photochemical Reflectance Index (PRI). Stemwood volume, basal area and tree height of dominant layer were negatively correlated with reflectance factors at both visible and NIR spectral region due to the increase in roughness of canopy surface and the amount of shade. Forest age was best related to single band reflectance at NIR region ( ρ = −0.48, p < 0.001) and the best predictor for allometric LAI was the single band reflectance at red spectral region ( ρ = −0.52, p < 0.001) outperforming all studied vegetation indices. It suggests that Sentinel-2 MSI bands with higher spatial resolution (10 m pixel size) could be more beneficial than increased spectral resolution for monitoring forest LAI and age. The new index R 751 /R 736 originally developed for leaf chlorophyll content estimation, also performed well at the canopy level and was mainly influenced by the location of red edge inflection point ( ρ = 0.99, p < 0.001) providing similar info in a simpler mathematical form and using a narrow spectral region very close to the O 2 -A Fraunhofer line.

scholarly journals Study of a High Spectral Resolution Hyperspectral LiDAR in Vegetation Red Edge Parameters Extraction

2019 ◽  
Vol 11 (17) ◽  
pp. 2007 ◽  
Author(s):  
Changhui Jiang ◽  
Yuwei Chen ◽  
Haohao Wu ◽  
Wei Li ◽  
Hui Zhou ◽  
...  
Keyword(s):  
Spectral Range ◽  
Spectral Resolution ◽  
Spatial Information ◽  
Research Direction ◽  
Parameter Extraction ◽  
Tunable Filter ◽  
High Spectral Resolution ◽  
Red Edge ◽  
Parameters Extraction ◽  
Vegetation Parameter

Non-contact and active vegetation or plant parameters extraction using hyperspectral information is a prospective research direction among the remote sensing community. Hyperspectral LiDAR (HSL) is an instrument capable of acquiring spectral and spatial information actively, which could mitigate the environmental illumination influence on the spectral information collection. However, HSL usually has limited spectral resolution and coverage, which is vital for vegetation parameter extraction. In this paper, to broaden the HSL spectral range and increase the spectral resolution, an Acousto-optical Tunable Filter based Hyperspectral LiDAR (AOTF-HSL) with 10 nm spectral resolution, consecutively covering from 500–1000 nm, was designed. The AOTF-HSL was employed and evaluated for vegetation parameters extraction. “Red Edge” parameters of four different plants with green and yellow leaves were extracted in the lab experiments for evaluating the HSL vegetation parameter extraction capacity. The experiments were composed of two parts. Firstly, the first-order derivative of the spectral reflectance was employed to extract the “Red Edge” position (REP), “Red Edge” slope (RES) and “Red Edge” area (REA) of these green and yellow leaves. The results were compared with the referenced value from a standard SVC© HR-1024 spectrometer for validation. Green leaf parameter differences between HSL and SVC results were minor, which supported that notion the HSL was practical for extracting the employed parameter as an active method. Secondly, another two different REP extraction methods, Linear Four-point Interpolation technology (LFPIT) and Linear Extrapolation technology (LET), were utilized for further evaluation of using the AOTF-HSL spectral profile to determine the REP value. The differences between the plant green leaves’ REP results extracted using the three methods were all below 10%, and the some of them were below 1%, which further demonstrated that the spectral data collected from HSL with this spectral range and resolution settings was applicable for “Red Edge” parameters extraction.

scholarly journals High spectral resolution ozone absorption cross-sections – Part 1: Measurements, data analysis and comparison with previous measurements around 293 K

2014 ◽  
Vol 7 (2) ◽  
pp. 609-624 ◽  
Author(s):  
V. Gorshelev ◽  
A. Serdyuchenko ◽  
M. Weber ◽  
W. Chehade ◽  
J. P. Burrows
Keyword(s):  
Data Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Spectral Resolution ◽  
Spectral Region ◽  
Uncertainty Budget ◽  
High Spectral Resolution ◽  
Absorption Cross ◽  
Ozone Absorption ◽  
Better Than

Abstract. In this paper we discuss the methodology of taking broadband relative and absolute measurements of ozone cross-sections including uncertainty budget, experimental set-ups, and methods for data analysis. We report on new ozone absorption cross-section measurements in the solar spectral region using a combination of Fourier transform and echelle spectrometers. The new cross-sections cover the spectral range 213–1100 nm at a spectral resolution of 0.02–0.06 nm in the UV–visible and 0.12–0.24 nm in the IR at eleven temperatures from 193 to 293 K in steps of 10 K. The absolute accuracy is better than three percent for most parts of the spectral region and wavelength calibration accuracy is better than 0.005 nm. The new room temperature cross-section data are compared in detail with previously available literature data. The temperature dependence of our cross-sections is described in a companion paper (Serdyuchenko et al., 2014).

scholarly journals High spectral resolution ozone absorption cross-sections – Part 1: Measurements, data analysis and comparison with previous measurements around 293 K

2013 ◽  
Vol 6 (4) ◽  
pp. 6567-6611 ◽  
Author(s):  
V. Gorshelev ◽  
A. Serdyuchenko ◽  
M. Weber ◽  
W. Chehade ◽  
J. P. Burrows
Keyword(s):  
Data Analysis ◽  
Cross Sections ◽  
Spectral Resolution ◽  
Spectral Region ◽  
Uncertainty Budget ◽  
Companion Paper ◽  
High Spectral Resolution ◽  
Absorption Cross ◽  
Ozone Absorption ◽  
Better Than

Abstract. In this paper we discuss the methodology of taking broadband relative and absolute measurements of ozone cross-sections including uncertainty budget, experimental set-ups, and methods for data analysis. We report on new ozone absorption cross-section measurements in the solar spectral region using a combination of Fourier transform and echelle spectrometers. The new cross-sections cover the spectral range 213–1100 nm at a spectral resolution of 0.02–0.06 nm in the UV-vis and 0.12–0.24 nm in the IR at eleven temperatures from 193 to 293 K in steps of 10 K. The absolute accuracy is better than three percent for most parts of the spectral region and wavelength calibration accuracy is better than 0.005 nm. The new room temperature cross-sections data are compared in detail with previously available literature data. The temperature dependence of our cross-sections is described in a companion paper.

Forest canopy chemistry with high spectral resolution remote sensing

1996 ◽  
Vol 17 (6) ◽  
pp. 1107-1128 ◽  
Author(s):  
F. ZAGOLSKI ◽  
V. PINEL ◽  
J. ROMIER ◽  
D. ALCAYDE ◽  
J. FONTANARI ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Spectral Resolution ◽  
Forest Canopy ◽  
High Spectral Resolution

Stimulated Raman Gain Spectroscopy Utilizing Counter-Propagating Pulsed Dye Lasers

1981 ◽  
Vol 35 (1) ◽  
pp. 81-85 ◽  
Author(s):  
James R. Nestor
Keyword(s):  
Spectral Resolution ◽  
Spectral Region ◽  
Low Frequency ◽  
Laser Beams ◽  
High Spectral Resolution ◽  
Laser Dyes ◽  
Raman Gain ◽  
Mechanical Waves ◽  
Bulk Medium ◽  
Coherent Raman

A simplified experimental arrangement, in which the laser beams are counter-propagating, has allowed the acquisition of Raman gain spectra without the aid of optically dispersive devices. The method allows high spectral resolution with the spatial rejection of fluorescence typical of coherent Raman techniques. Access to the low-frequency spectral region has revealed stimulated gain involving mechanical waves of the bulk medium. Quasi-continuous scans of the entire vibrational region have been made using only two laser dyes.

scholarly journals Oxygen in Unevolved Starss

2002 ◽  
Vol 12 ◽  
pp. 416-419
Author(s):  
Ann Merchant Boesgaard
Keyword(s):  
Spectral Resolution ◽  
Linear Relation ◽  
Spectral Region ◽  
High Spectral Resolution ◽  
High Signal ◽  
Signal To Noise ◽  
Spectrum Synthesis ◽  
Ultraviolet Spectral Region

AbstractWe have made observations of 24unevolvedstars of the OH lines in the ultraviolet spectral region at high spectral resolution and high signal-to-noise, typically 60 − 110 with Keck + HIRES. The O abundances have been computed by spectrum synthesis. For these cool, unevolved stars there is a linear relation between [O/H] and [Fe/H] over three orders of magnitude with very little scatter and a slope of +0.66 ±0.02. The relation between [O/Fe] and [Fe/H] is robustly linear with [O/Fe] = −0.35 (±0.03) [Fe/H]. There is no sign of a break at metallicities between −1.0 and −2.0.

Sign in / Sign up

Export Citation Format

Share Document