Open AccessAuroral records from Canada 1769–1821
Author(s) -
Broughton Peter
Publication year - 2002
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001ja000241
Subject(s) - latitude , solar minimum , sunspot , geomagnetic latitude , solar maximum , earth's magnetic field , sunspot number , high latitude , atmospheric sciences , environmental science , meteorology , solar cycle , climatology , geography , geology , physics , geodesy , solar wind , plasma , magnetic field , quantum mechanics
Over 1000 previously unused Canadian auroral observations from manuscript sources between 1771 and 1819 are examined. They are especially reliable because they are part of meteorological registers which simultaneously contain information on cloudiness and are significant because they add substantially to the scarce database of historical records, especially from high geomagnetic latitudes (57° < Φ 1800 < 70°). The statistics derived from these data show an interval of low auroral activity from about 1785 to 1815, a decade earlier than the Dalton solar activity minimum, superimposed on a fairly regular periodicity of about 11 years and seasonal variations. The relationship between the auroral occurrence frequency and solar activity from 1795 to 1815 is similar to what is normally seen at lower latitudes suggesting that the auroral oval contracted more than usual during the Dalton minimum. The data support the type of relationship found by Ohl, which directly relates the frequency of auroral occurrence at high latitudes during the declining portion of one solar cycle to the sunspot number at the following maximum and the rapidity with which the solar activity returns to a maximum.