Summary
The absolute errors to be expected in reflectivity measured with four different types of commercially available 2nd Class pyranometers have been enumerated and evaluated from laboratory studies and W. M. O. recommendations. The maximum errors to be expected were between ±10 and ±20% at a solar elevation of 60° and between ±20 and ±30% for a solar elevation of 10°. The comparative error, i. e., the difference in reflectivity measured by different types of pyranometers, was measured under field conditions and reached 25% at a solar elevation of 60° and 40% at 10°. Random errors, including those due to individual differences in pyranometers of the same type, were found to be negligibly small. Large and asymetrial diurnal variations in reflectivity were observed. They paralleled the diurnal changes in the fraction of diffuse incident radiation, but could not be explained by changes of the fractional infrared composition of solar radiation as the latter were very small. Analysis by multiple regression suggested that the reflectivity for the direct beam radiation was higher than for the diffuse radiation.
Zusammenfassung
Die absoluten Fehler, die zu erwarten sind, wenn man die Reflexion mit vier verschiedenen von der Industrie gelieferten Pyranometern der Kategorie 2 nach der WMO-Einteilung mißt, wurden in Laboratoriumsexperimenten entsprechend WMO-Rekommandationen bestimmt und berechnet. Die maximalen Fehler, die man erwarten muß, liegen zwischen ±10 und ±20% bei einer Sonnenhöhe von 60° und zwischen ±20 und ±30% bei einer Sonnenhöhe von 10°. Die Abweichungen zwischen den Instrumenten, d. h. die Unterschiede der Reflektivität, wenn man sie mit verschiedenen Arten von Pyranometern mißt, wurden im Feld bestimmt und erreichten 25% bei einer Sonnenhöhe von 60° und 40% bei 10°. Die Zufallsfehler, welche auch die Fehler umfassen, die durch individuelle Unterschiede der einzelnen Pyranometer derselben Type entstehen, wurden als vernachlässigbar klein erkannt. Es wurden große und unsymmetrische Tagesgänge der Reflektivität beobachtet. Sie verlaufen parallel zum Tagesgang des Anteils der diffusen einfallenden Strahlung, können aber nicht durch Änderungen im Ausmaß des infraroten Spektralanteils der Sonnenstrahlung erklärt werden, da der letztere sehr klein war. Eine Untersuchung mit multiplen Regressionen ergab, daß die Reflektivität für direkte Strahlung höher ist als für diffuse Strahlung.
Similar content being viewed by others
References
Anderson, M. C.: The Role of Heat Transfer in the Design and Performance of Solarimeters. J. appl. Meteorol.6, 941–947 (1967).
Ångström, A.: The Solar Constant and the Temperature of the Earth. Progress in Oceanography3, 1–5 (1965).
Brounstein, A. M., K. D. Lebedeva, andS. I. Sivkov: Influence of Spectral Characteristics of Receiving Surfaces of Instruments on the Accuracy of Measuring Radiant Fluxes. P. 218–226, in: Actinometry and Atmospheric Optics, Tallinn, Valgus (1968).
Colwell, R. N.,et al.: Basic Matter and Energy Relationships Involved in Remote Reconnaissance. Photogr. Engng29, 761–799 (1963).
Cowan, I. R.: The Interception and Absorption of Radiation in Plant Stands. J. appl. Ecol.5, 367–379 (1968).
Drummond, A. M.: On the Measurement of Sky Radiation. Arch. Met. Geoph. Biokl., B,7, 414–436 (1956).
Drummond, A. M.: The Absolute Calibration of Thermal Radiation Detectors. Proc. 22nd Ann. Conf. Instrument Soc. America P 6-1-PHYMMID-67 (1967).
Drummond, A. M.: Instruction Manual: Solar Radiation Instrumentation and Measurement Methods. U.S. Army Natick Laboratories, S. O. 18248 (DAAG 17-67-M-2421) (1968).
Flowers, E. C., andN. F. Helfert: Laboratory and Field Investigations of Eppley Radiation Sensors. Mo. Weather Rev.94, 259–264 (1966).
Fuquay, D., andK. Buettner: Laboratory Investigations of Some Characteristics of the Eppley Pyrheliometer. Trans. Am. geophys. Un.38, 38–43 (1957).
Gates, D. M.: Radiant Energy, Its Receipt and Disposal. Meteorological Monographs6, 1–26 (1965).
Griffiths, J. S.: Test Requirements, in: Handbook of Solar Simulation for Thermal Vacuum Testing. CR. 4, pp. 1–23. Institute of Environmental Sciences, Mt. Prospect, Ill. (1968).
Grulois, J.: La variation annuelle du coefficient d'albedo des surfaces superieures du Peuplement. Bull. Soc. R. Bot. Belgique101, 141–153 (1968).
Hamilton, R. A., andR. H. Collingbourne: A Difficulty in the Interpretation of Certain Solar Radiation Measurements. Q. J. R. Met. Soc.93, 186–194 (1967).
Harris, L.: The Optical Properties of Metal Blacks and Carbon Blacks. Monograph Series No. 1. The Eppley Foundation for Research, Newport, R. I. (1967).
Hart, H. E., andN. J. Rosenberg: An Extended Cylindrical Shield for Use with an Inverted Eppley Pyranometer to Measure Albedo over Small Areas. Hort. Prog. Rep.60, 30–42. Univ. of Nebraska agric. Exp. Stn. (1967).
Hill, A. N.: Calibration of Solar Radiation Equipment in the U. S. Weather Bureau. Solar Energy10, 1–4 (1966).
Howard, J. A.: Spectral Energy Relations of Isobilateral Leaves. Aust. J. biol. Sci.,19, 757–766 (1966).
Isobe, S.: Preliminary Studies on Physical Properties of Plant Communities. Bull. Natn. Inst. Agric. Sci. (Japan), A,9, 29–67 (1962).
Latimer, J. R.: Calibration Program of the Canadian Meteorological Service. Solar Energy10, 4–7 (1966).
Latimer, J. R.: Investigation of Solar Radiation Instruments at the National Atmospheric Radiation Centre of the Canadian Meteorological Service. Paper No. 3/1, Int. Solar Energy Soc. Conf., Melbourne (1970).
Lettau, H., andK. Lettau: Short Wave Radiation Climatonomy. Tellus21, 208–222 (1969).
MacDonald, T. H.: Some Characteristics of the Eppley Pyrheliometer. Mo. Weather Rev.79, 153–159 (1951).
Mantell, A. andG. Stanhill: Comparison of Methods for Evaluating the Response of Lawn Grass to Irrigation and Nitrogen Treatment. Agron. J.58, 465–468 (1966).
Monteith, J. L.: Solarimeter for Field Use. J. Scient. Instrum.36, 341–346 (1959).
Rijks, D. A.: Water Use by Irrigated Cotton in Sudan. 1. Reflection of Short-Wave Radiation. J. Appl. Ecol.4, 561–568 (1967).
Robinson, N.: Solar Radiation. New York: Elsevier, 1966.
Rusin, N.: Meteorological and Radiational Regime of Antarctica. Israel Progr. Scient. Transl., Jerusalem, 1964.
Scott, D., P. H. Menalda, andR. W. Brougham: Spectral Analysis of Radiation Transmitted and Reflected by Different Vegetations. N. Z. J. Bot.6, 427–449 (1968).
Simpson, G. C.: Further Studies in Terrestrial Radiation. Mem. R. Meteor. Soc.3, 1–26 (1928).
World Meteorological Organization: Measurement of Radiation and Sunshine. Guide to Meteorological Instruments and Observing Practices. 2nd ed., Geneva, 1965.
Author information
Authors and Affiliations
Additional information
With 7 Figures
Contribution from The Volcani Institute of Agricultural Research, Bet Dagan, Israel. 1970 Series, No. 1810-E.
Rights and permissions
About this article
Cite this article
Stanhill, G., Fuchs, M. & Oguntoyinbo, J. The accuracy of field measurements of solar reflectivity. Arch. Met. Geoph. Biokl. B. 19, 113–132 (1971). https://doi.org/10.1007/BF02332259
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02332259