The work was divided in five Subtasks, each coordinated by a lead country:
Subtask A dealt with field inter-comparisons of existing spectro-radiometers and pyrgeometers and characterized these instruments as a function of inclination, temperature, direction and spectral composition of incoming radiation, in order to specify uncertainty and predict performance.
Subtask C focused on increasing the available amount of narrow-band spectral radiation data by measurement, evaluation and analyses of such data and associated quantities under various atmospheric conditions and climates, and the compilation and publication of such data.
In order to increase the quality of modelled spectral radiation data, experts in Subtask D compiled narrow-band spectral radiation models for arbitrary atmospheric and ground surface conditions, and improved the methods of estimating meteorological parameters needed as input to such models.
Solar illuminance and luminance data and related solar irradiance and radiance data were acquired under Subtask E, following the guidelines of the International Daylight Measuring Program (IDMP), and data analysis and model validation were conducted in order to increase the available amount of daylighting data.
To provide input needed for energy balance analysis of solar systems
and buildings, the participants in Subtask F acquired and evaluated (longwave)
atmospheric radiation and related data under various specified
atmospheric conditions and climates, and reviewed and validated
parameterizations for atmospheric radiation, relating to both horizontal