58 research outputs found
Errors in Scale Values for Magnetic Elements for Helsinki
Using several lines of evidence we show that the scale values of the
geomagnetic variometers operating in Helsinki in the 19th century were not
constant throughout the years of operation 1844-1897. Specifically, the adopted
scale value of the Horizontal Force variometer appears to be too low by ~30%
during the years 1866-1874.5 and the adopted scale value of the Declination
variometer appears to be too low by a factor of ~2 during the interval
1885.8-1887.5. Reconstructing the Heliospheric Magnetic Field strength from
geomagnetic data has reached a stage where a reliable reconstruction is
possible using even just a single geomagnetic data set of hourly or daily
values. Before such reconstructions can be accepted as reliable, the underlying
data must be calibrated correctly. It is thus mandatory that the Helsinki data
be corrected. Such correction has been satisfactorily carried out and the HMF
strength is now well constrained back to 1845
Does Building a Relative Sunspot Number Make Sense? A Qualified 'Yes'
Recent research has demonstrated that the number of sunspots per group
('active region') has been decreasing over the last two or three solar cycles
and that the classical Relative Sunspot Number (SSN) no longer is a good
representation of solar magnetic activity such as revealed by e.g. the F10.7 cm
microwave flux. The SSN is derived under the assumption that the number of
spots per group is constant (in fact, nominally equal to 10). When this is no
longer the case (the ratio is approaching 5, only half of its nominal value)
the question arises how to construct a sunspot number series that takes that
into account. We propose to harmonize the SSN with the sunspot Group Count that
has been shown to follow F10.7 very well, but also to include the day-to-day
variations of the spot count in order to preserve both long-term and short-term
variability.Comment: 4 pages, 1 Figur
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