Derivation of surface direct beam spectral albedo for a wide range of incident angles from spectral reflectance measurements under overcast conditions

2002 ◽  
Author(s):  
Shusun Li ◽  
Xiaobing Zhou
Keyword(s):  
Spectral Reflectance ◽  
Direct Beam ◽  
Wide Range ◽  
Reflectance Measurements

Characterization of Quantum well Structures Using Microscope-Spectrophotometry

1993 ◽  
Vol 324 ◽  
Author(s):  
Rachel M Geatches ◽  
Karen J Reeson ◽  
Alan J Criddle ◽  
Roger P Webb
Keyword(s):  
Quantum Wells ◽  
Spectral Reflectance ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
Measurement Range ◽  
Aluminium Content ◽  
Quantum Well Structures ◽  
Nondestructive Characterization ◽  
Reflectance Measurements

AbstractIn this paper the application of microscope-spectrophotometry to the nondestructive characterization of a variety of multi-layer GaAs/A1GaAs structures, is described. Spectral reflectance results are used to indirectly determine variations in aluminium content, and the interdependency of aluminium content with layer thicknesses. The penetration depth of light from the visible spectrum is assessed from the correlation between spectral reflectance measurements and fitted optical models. Finally, a series of single quantum wells are investigated, and it is concluded that a significant improvement in the characterization of these materials will be achieved with an extension of the spectral measurement range into the ultra violet.

Regional predictions of soil organic carbon content from spectral reflectance measurements

2009 ◽  
Vol 104 (3) ◽  
pp. 442-446 ◽  
Author(s):  
H. Aïchi ◽  
Y. Fouad ◽  
C. Walter ◽  
R.A. Viscarra Rossel ◽  
Zohra Lili Chabaane ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Spectral Reflectance ◽  
Organic Carbon Content ◽  
Soil Organic Carbon Content ◽  
Reflectance Measurements

Canopy structure and imaging geometry may create unique problems during spectral reflectance measurements of crop canopies in bioregenerative advanced life support systems

2007 ◽  
Vol 6 (2) ◽  
pp. 109-121
Author(s):  
Andrew C. Schuerger ◽  
Kenneth L. Copenhaver ◽  
David Lewis ◽  
Russell Kincaid ◽  
George May
Keyword(s):  
Remote Sensing ◽  
Plant Growth ◽  
Spectral Reflectance ◽  
Life Support ◽  
Support Systems ◽  
Canopy Structure ◽  
Advanced Life Support ◽  
Sensing System ◽  
Plant Canopies ◽  
Reflectance Measurements

AbstractHuman exploration missions to the Moon or Mars might be helped by the development of a bioregenerative advanced life-support (ALS) system that utilizes higher plants to regenerate water, oxygen and food. In order to make bioregenerative ALS systems competitive to physiochemical life-support systems, the ‘equivalent system mass’ (ESM) must be reduced by as much as possible. One method to reduce the ESM of a bioregenerative ALS system would be to deploy an automated remote sensing system within plant production modules to monitor crop productivity and disease outbreaks. The current study investigated the effects of canopy structure and imaging geometries on the efficiency of measuring the spectral reflectance of individual plants and crop canopies in a simulated ALS system. Results indicate that canopy structure, shading artefacts and imaging geometries are likely to create unique challenges in developing an automated remote sensing system for ALS modules. The cramped quarters within ALS plant growth units will create problems in collecting spectral reflectance measurements from the nadir position (i.e. directly above plant canopies) and, thus, crop canopies likely will be imaged from a diversity of orientations relative to the primary illumination source. In general, highly reflective white or polished surfaces will be used within an ALS plant growth module to maximize the stray light that is reflected onto plant canopies. Initial work suggested that these highly reflective surfaces might interfere with the collection of spectral reflectance measurements of plants, but the use of simple remote sensing algorithms such as 760/685 band ratios or normalized difference vegetation index (NDVI) images greatly reduced the effects of the reflective backgrounds. A direct comparison of 760/685 and NDVI images from canopies of lettuce, pepper and tomato plants indicated that unique models of individual plants are going to be required to properly assess the health conditions of canopies. A mixed model of all three plant species was not effective in predicting plant stress using either the 760/685 or NDVI remote sensing algorithms.

scholarly journals Managing Nitrogen, Potassium, and Boron in New Guinea Impatiens: Is More Better?

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 777B-777
Author(s):  
Dharmalingam S. Pitchay* ◽  
Jonathan M. Frantz ◽  
Jonathan M. Locke ◽  
Charles Krause
Keyword(s):  
New Guinea ◽  
Production Costs ◽  
Plant Performance ◽  
Nutrient Deficiencies ◽  
Tissue Samples ◽  
Wide Range ◽  
New Guinea Impatiens ◽  
Reflectance Measurements ◽  
Insight Into

Growers tend to over fertilize their plants as a way to minimize the likelihood of encountering nutrient deficiencies that would reduce the quality of their plants. Much of the nutrition literature focuses on the nutritional extremes namely of toxicity and deficiency. Once plants get to this stage, little can be done to correct the problem. Characteristics of plant performance in super-optimal conditions, yet below toxic levels, is less well known, and needs to be developed to help growers identify problems in their production practices before they impact sales. New Guinea Impatiens were grown over a wide range of N, K, and B levels, from 15% to 400% full strength Hoagland's solution for each nutrient after establishing transplanted rooted cuttings in a peat: perlite soilless media. Plants were grown for four weeks during treatment, during which time the flowers were pinched. After only 2 weeks of treatment, plants with 200% and 400% N were significantly shorter than control plants and plants with 15% N. Reflectance measurements and photographs were made twice a week. At the end of the four weeks, plant tissue was analyzed for form of N, root development and structure, and leaf area. Tissue samples were also analyzed with SEM and energy dispersive X-ray analysis to determine changes in nutrient location and tissue structure. This data provides insight into the nutrition economy of plants in general, tests the use of reflectance spectrometry as a method of detecting super-optimal fertilizer concentrations, and will help growers optimize their fertilization requirements to reduce production costs yet maintain high plant quality.

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