Establishment of a radiation network connected to ordinary weather stations and evaluation of their observations

Summary

This paper describes instruments and evaluation methods of a radiation network established some time ago under the technical supervision of the author. The network is closely attached to a normal network of meteorological stations and instruments are operated by meteorological personnel.

Observations at each station cover direct solar radiation, short wave sky radiation and outgoing radiation while continuous recordings of global radiation are also obtained. The instrument used for the latter purpose, theRobitzsch-actinograph, is the only orthodox and commonly known apparatus among the network equipment. All other instruments had to be developed with particular regard to simple operation. At the same time, their design aimed at measurement accuracies at least equal to those of radiation equipment utilized so far.

Entirely new ways have also been created for the evaluation of results, in order to make measurements with secondary radiation equipment, as much as possible, independent of frequent calibrations by means of standard apparatus at the central observatory. This has been achieved by determining the appropriate constants of the instruments from their own series of observation. For this purpose, the writer's formula for global radiation, found twenty years ago and more recently confirmed theoretically, was available. It allows that radiation component at clear sky to be calculated as monthly mean values within a few percent. The formula enables the calibration factors of theRobitzsch-actinograph, known to be affected by both annual and diurnal variations, to be determined from hour to hour. Thus errors of all hourly mean values should not exceed ±5%. The validity of the method is proved by obvious agreement of calibration factors for the same month in different years.

For actinometrical measurements, the paper describes a method whose application allows the solar constant to be determined from measurements of one season, or viceversa, as this quantity is known, calibration factors of the actinometer used may be found for the total radiation behind different filters.

Corresponding methods for pyrgeometric measurements are also discussed in the paper.

Beside the description of a new simple photographic recorder for global radiation at day and night a survey has been made of meteorological problems solvable by recordings of that radiation.