Seasonal and sunspot-cycle changes in the day-to-day variability ofSq

Abstract

SUMMARY A study has been made of seasonal and sunspot-cycle changes in the day-to-day variability of Sq, using data from magnetic observatories for which long runs exist. For sunspot-cycle changes, the absolute variability, as measured by the standard deviation (sd) of the range, increases from sunspot minimum to sunspot maximum. However, the ratio of sd to range, arguably a more meaningful parameter physically, is generally smaller at sunspot maximum than sunspot minimum. This is interpreted to show that the fractional variability in dynamo winds is less at sunspot maximum than sunspot minimum. The seasonal changes of variability show consistent global patterns, including an interesting hemispheric asymmetry.