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Measurements of Declination at the Helsinki Magnetic-meteorological Observatory 1844-1853A project was started with the goal of putting into computer readable form all the old unpublished magnetic data at the Finnish Meteorological Institute (FMI), the successor of the Helsinki magnetic-meteorological observatory. Altogether there are available about 2.5 million visual observations of D, H and Z made during the time interval 1844-1905. The first 10 year period (1844-1853) of declination data now converted to electronic form, includes observations made at every tenth minute. The total number of observations is 489,152. We present some examples of declination observations in forms of tables and graphs showing hourly, daily, monthly, and annual means. Secular variations of the declination in 1844-1853 have been extremely linear, showing a steady eastward increase of 8 prime/year that is more than two times larger than the present annual rate of secular change in Finland. The standard deviation of the daily and monthly residuals, after removing the secular variation trend for the whole time period, is about 1 prime, demonstrating the high stability and reliability of the observations. For this reason the data may be suitable for deriving a 3-hour activity index K and daily Ak numbers, giving new information for extending the existing long series of activity characters backwards in time.
Document ID
19920019379
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Nevanlinna, Heikki
(Finnish Meteorological Inst. Helsinki, Finland)
Ketola, Anneli
(Finnish Meteorological Inst. Helsinki, Finland)
Kangas, Tuulikki
(Finnish Meteorological Inst. Helsinki, Finland)
Date Acquired
September 6, 2013
Publication Date
June 1, 1992
Publication Information
Publication: NASA. Goddard Space Flight Center, Types and Characteristics of Data for Geomagnetic Field Modeling
Subject Category
Geophysics
Accession Number
92N28622
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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