Observations of the Earth's magnetic field made in Edinburgh from 1670 to the present day

Abstract

Magnetic observations made at the same site give valuable information about the time changes (the secular variation) of the geomagnetic field. This paper gives details of all known measurements of the geomagnetic field in and around Edinburgh since the earliest observation of magnetic declination (the difference between true and magnetic north) by George Sinclair in 1670. Early observations of the strength of the field were only relative measurements. Approximate conversion factors are derived to enable these data to be expressed in modern absolute units (nanoteslas). Observed values of declination, inclination and the horizontal intensity of the geomagnetic field are plotted and compared with values computed from mathematical models of the field covering the interval 1690 to 1990, inclusive. The earlier observations were not corrected for the effects of the rapidly varying magnetic fields caused by electric currents in the upper atmosphere. The consequences of this are estimated.

High‐resolution secular variation of the geomagnetic field in western Europe over the last 4 centuries: Comparison and integration of historical data from Paris and London

“…A new series (Ia) is produced by smoothing the inclination annual means (I*) with an 11-year moving average filter (Figure 14). [Barraclough, 1995] and curves of declination evolution are available for Freiberg [RSsler et al, 1978] and Rome [Cafarella et al, 1992]. Several other sites in Europe are rich in historical magnetic observations.…”

Geomagnetic field declination: from decadal to centennial scales

“…-Edinburgh: raw data published by Barraclough (1995), adjusted to Eskdalemuir observatory (ESK); -London: raw data published by Malin and Bullard (1981), adjusted to Hartland observatory (HAD); 5 -Paris: raw data published by Alexandrescu et al (1996Alexandrescu et al ( , 1997 and reviewed recently by Mandea and Le Mouël (2016), adjusted to Chambon la Foret observatory (CLF); -Munich: 11-year filtered smoothing spline fitted to raw data, as published by Korte et al (2009), adjusted to Furstenfeldbruck observatory (FUR); -Rome: assembled time-series using data published by Cafarella et al (1992 b) for Rome area and for three 10 successively operating Italian observatories (Pola, 1881(Pola, -1922Castellaccio, 1933Castellaccio, -1962L'Aquila, 1960L'Aquila, -2011, adjusted to L'Aquila observatory (AQU).…”

“…Additionally, a special attention is given to the 11-year 20 solar-cycle-related constituent, present in the declination annual means. Finally, we elaborate on our previous analysis of three very long declination time-series, by i) including in the analysis two more: Paris (Alexandrescu et al, 1996(Alexandrescu et al, , 1997Mandea and Le Mouël, 2016) and Edinburgh (Barraclough, 1995), ii) discussing the first time derivative of the five timeseries, iii) comparing in detail our analysis on jerk occurrence to the Alexandrescu et al (1997) and Korte et al (2009) ones, and iv) comparing with time-series provided by the gufm1 main field model by Jackson et al (2000). …”

After some 350 years – zero declination again in Paris

“…We can quote the time series of declination and sometimes inclination which have been compiled by (Malin and Bullard, 1981), Cafarella et al (1992), Barraclough (1995), Alexandrescu et al (1996) and Korte et al (2009) for London, Rome, Edinburgh, Paris and Munich respectively.…”

“…The annual means -1541-1994: from Alexandrescu et al (1996);-1995-2014: from http://www.geomag.bgs.ac.uk/data_ service/data/annual_means.shtml.…”