CIE 085-1989

CIE TC2-17 was formed with the purpose of updating CIE 20 (TC-2.2) Recommendations for the integrated irradiance and the spectral distribution of simulated solar radiation for testing purposes. The present document is the first of two, of which the second will deal with solar simulators. It gives a brief overview of parameterization methods and contains a number of tables and figures for solar spectral irradiances for typical atmosphere conditions defined by a set of meteorological parameters. The calculated data show satisfactory agreement with results obtained by direct measurement.

It has become obvious that the solar spectral irradiance data on which the recommendations in the original document were based were no longer the most reliable. During the past decade a vast amount of new data has become available both through modernized measurement techniques as well as improved modelling and parameterization methods. Contrary to the situation some years ago, the stage has now been reached where results for solar spectral irradiances at ground level as measured and those obtained by reliable modeling, using extraterrestrial data as basis, show agreement to accuracies well within predictable or estimable uncertainties. It has thus become possible to calculate solar spectral irradiance levels and characteristics for any site on earth provided appropriate meteorological and atmospheric parameters are applied in reliable modeling formulas. This enables close simulation of solar irradiance characteristics for any geographical site, without the need of having to make in situ measurements.

It is also desirable that the number of spectral bands for which integrated solar irradiance levels are given, should be increased, especially in the ultraviolet region where the degradation coefficient for organic material increases nearly exponentially with a decrease in wavelength.

The aim of the report is to present data and recommend methods for calculating the integrated and spectral irradiance of the extraterrestrial and ground level solar radiation as a basis for simulation for testing purposes. These data are required in

* aerospace technique for testing satellites and space vehicles in sun simulators,
* space biology for testing biological objects under extra-terrestrial conditions in laboratory,
* technology for the purpose of testing the resistance of technical objects to irradiance in laboratories,
* biology and medical science for irradiation of organisms in solaria under the condition found in nature, and
* photovoltaic conversion for precise calculation of efficiencies and testing in solar simulators.

For obtaining ground level spectral irradiance data, use has been made of modelling, using extraterrestrial data as a basis and taking into account atmospheric attenuation parameters. This has been supplemented by direct spectral measurement.

The Technical Report consists of 48 pages with 11 figures and 8 tables.