How are magnetic storms on Earth related to sunspot activity?
Earth’s field is sum of 3 parts: External Magnetic Field Anomalous Induced Magnetic Field Main Magnetic Field 1. External magnetic field about 1-5% of total field biggest secular variation is diurnal, with an amplitude of tens of nT also a seasonal variation, i.e., diurnal variation greatest in summer strongest at equator all suggest role of sun EM (UV and x-rays) ionizes particles in ionosphere Sun’s tidal force produces cyclic wind currents in ionosphere, which in turn produces electrical currents ionosphere directly produces 2/3 of observed diurnal effect; induced currents in Earth contribute about 1/3 magnetic storms: external field occasionally variable over minutes, at hundreds of nT or more (magnetic storm) from 100s to 1000s of nT sunspot number is computed according to the Wolf Sunspot Number R=k (10g+s), where g is the number of sunspot groups (regions), s is the total number of individual spots in all the groups, and k is a variable scaling factor (usually <1) that indicates
