Results of Russian geomagnetic observatories in the 19th century: magnetic activity, 1841–1862

H Nevanlinna,L Häkkinen

doi:10.5194/angeo-28-917-2010

Abstract

Abstract. Hourly (spot readings) magnetic data (H- and D-components) were digitized from Russian yearbook tables for the years 1850–1862 from four observatories. The pdf pictures for digitization were taken by a normal digital camera. The database obtained consists of about 900 000 single data points. The time series of hourly magnetic values reveal slow secular variations (declination only) as well as transient and regular geomagnetic variations of external origin. The quality and homogeneity of the data is satisfactory. Daily Ak-indices were calculated using the index algorithm that has been earlier applied to 19th century data from Helsinki (Finland) as well as modern magnetic observatory recordings. The activity index series derived from the Russian data is consistent with earlier activity index series for 1850–1862. The digitized index data series derived in this study was extended back to 1841 by including magnetic C9 activity index data available from a Russian observatory (St. Petersburg). Magnetic data rescued here is well suitable for various reconstructions for studies of the long-term variation of the space weather in the 19th century.

Highlights

The history of Russian geomagnetic network goes back to the 1820s when a resurgence of interest in geomagnetism took place in the international scientific community
Ak-indices were calculated using the index algorithm that has been earlier applied to 19th century data from Helsinki (Finland) as well as modern magnetic observatory recordings
Magnetic data rescued here is well suitable for various reconstructions for studies of the long-term variation of the space weather in the 19th century

Summary

Introduction

The history of Russian geomagnetic network goes back to the 1820s when a resurgence of interest in geomagnetism took place in the international scientific community. The Helsinki observatory started its operations in 1844 and they continued, largely unchanging, with the same magnetic instrumentation for almost 70 years until 1912 (Nevanlinna, 2004). Original Russian yearbooks have been preserved, in more or less complete collections, and they are available in libraries of several countries that were in co-operation in magnetism and meteorology with Russia in the 19th century. This discovery, soon modified and completed by e.g., Ampere, gave a great impetus for scientific studies of the true character of the origin of the Earth’s magnetic field: The Earth would be a huge electromagnet maintaining its magnetic field by induction mechanisms rather than by permanent magnetism proposed by Gilbert in 1600 It was known in the early 19th century that regular daily variation of magnetic elements followed the local solar time showing largest deviation near midday. The index algorithm applied to the Russian data (Menvielle et al, 1995) (based on hourly values) is the same that has been utilized in the analysis of Helsinki (Finland) magnetic observatory data 1844–1897 (Nevanlinna, 2004)

Magnetic observations

Digitization of tabulated observatory data

Time series of magnetic data 1850–1862

Magnetic activity