TY - JOUR
T1 - Field calibration of reference reflectance panels
AU - Jackson, Ray D.
AU - Susan Moran, M.
AU - Slater, Philip N.
AU - Biggar, Stuart F.
N1 - Funding Information:
The rangeo f differencefsro mthe mean of seven measuremenotfs V(O°/O) for the pressed-halosnt andardw as +0.2% for incidencea nglesr angingf rom2 0° to 70° . It is reasonablteo assumet hat the We wish to thank I. B. Schutt for the same precision can be obtained for construction of the painted halon panel V(O°/O) of the referencpea nelsC. onsid-# 3, Che Nianzeng for the construction of ering the variousf actorsi,t is our opinion BaSO 4 panels :#:10 and #11, and C. M. U. that the accuracyo f the methodis on the Neale for construction and the loan of order of 1%, althoughth is is difficult to panel #12. We avpreciate the creative verify. assistance of W. C. Bausch, C. M. U. Major advantageosf the techniquefo r Neale, T. R. Clarke, and H. L. Kelly reference-panceall ibratiodne scribehde re during the conduct of the experiments. over conventionalal boratoryc alibration Thanks are due W. C. Bausch, 1. 1. Hsia, methodasr e,first, that the irradiancea nd F. E. Nicodemus, and P. M. Teillet for viewingg eometryis the samea s is used their constructive suggestions towards im-in field measuremenatns d, second,t hat proving the manuscript. The University the equipmenat nd facilitiesn eededa re of Arizona authors acknowledge NASA availableo r can be constructeadt many support under Contract No. NAS5-27382 field researchs tationsH. alon powderi s and Grant No. NAG5-196. commerciallayv ailablea, ndthe necessary tools to constructa pressed-halosnt an-dard can usuallyb e obtainedA. disad-vantageo f the techniqueis that the sky must be sufficientlyc loud-freet hat sky irradiancec hangesa re minimal during the measuremenpte riod. This requirement can be restrictived uringl ongperi-ods of cloudyw eather. Reflectancef actors for panels con-structedb y the samep ersona t the same
PY - 1987/6
Y1 - 1987/6
N2 - The measurement of radiation reflected from a surface must be accompanied by a near-simultaneous measurement of radiation reflected from a reference panel in order to calculate a bidirectional reflectance factor for the surface. Adequate calibration of the reference panel is necessary to assure valid reflectance-factor data. A procedure is described by which a reference panel can be calibrated with the sun as the irradiance source, with the component due to diffuse flux from the atmosphere subtracted from the total irradiance. Furthermore, the radiometer that is used for field measurements is also used as the calibration instrument. The reference panels are compared with a pressed polytetrafluoroethylene (halon) standard. The advantages of this procedure over conventional laboratory calibration methods are, first, that the irradiance and viewing geometry is the same as is used in field measurements and, second, that the needed equipment is available, or can be constructed, at most field research laboratories, including the press necessary to prepare the halon standard. A disadvantage of the method is that cloud-free sky conditions are required during the measurement period. The accuracy of the method is estimated to be 1%. Calibration results are given for four reference panels.
AB - The measurement of radiation reflected from a surface must be accompanied by a near-simultaneous measurement of radiation reflected from a reference panel in order to calculate a bidirectional reflectance factor for the surface. Adequate calibration of the reference panel is necessary to assure valid reflectance-factor data. A procedure is described by which a reference panel can be calibrated with the sun as the irradiance source, with the component due to diffuse flux from the atmosphere subtracted from the total irradiance. Furthermore, the radiometer that is used for field measurements is also used as the calibration instrument. The reference panels are compared with a pressed polytetrafluoroethylene (halon) standard. The advantages of this procedure over conventional laboratory calibration methods are, first, that the irradiance and viewing geometry is the same as is used in field measurements and, second, that the needed equipment is available, or can be constructed, at most field research laboratories, including the press necessary to prepare the halon standard. A disadvantage of the method is that cloud-free sky conditions are required during the measurement period. The accuracy of the method is estimated to be 1%. Calibration results are given for four reference panels.
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U2 - 10.1016/0034-4257(87)90032-0
DO - 10.1016/0034-4257(87)90032-0
M3 - Article
AN - SCOPUS:0023524713
VL - 22
SP - 145
EP - 158
JO - Remote Sensing of Environment
JF - Remote Sensing of Environment
SN - 0034-4257
IS - 1
ER -