Some preliminary results of the geomagnetic survey of the northern part of the Federal Republic of Germany in 1982

Conclusion

As forF, further improvements can be hardly expected; that applies to both technique of measurement and reduction routine.

The effort of reduction according to additional stations is considerable. On principle, the effort can be cut down, if future surveys will be conducted during years of the quiet sun, i. e., minimum particle radiation, again — as was the case in 1965.0 and 1935.0. Then, obviously, in most cases a correction derived from the deviations of hourly means against daily means (Voppel, Wienert [1974]) of the reference observatories (WNG and FUR) may be sufficient, provided that the measurements are carried out not between the early morning and the late afternoon. At noon, both longitude and latitude influences become maximum and most complicated, as was revealed by a statistic investigation (Voppel, Wienert [1974]) and also by an isolated case (Schulz, Beblo [1984]). Only measurements carried out during disturbed intervals and during strong Sq variations are to be reduced according to the nearest of a few additional high-quality variation stations.

What is valid for the reduction ofF, that is valid for the other components, because theF variations were calculated fromH andZ variations. From this follows that the residuals ofD and particularly ofI to a great extent are due to uncertainties of measurement. Therefore, in the future, efforts must be focused upon a reliable reproduction of the standards of these components at secular points. However, as has been emphasized in the beginning, only the next survey can clarify as to what extent the probe theodolite contributes to the uncertainty of measurement.