Solar influence on meteor rates and atmospheric density variations at meteor heights

Lindblad (1967) has concluded that there was an inverse relation between meteor rates and the solar cycle brought about by an increase in atmospheric density gradient at the height of meteor ionization. The present paper investigates Lindblad's conclusion more fully by using three long series of continuous radar meteor data from New Zealand and Canada. The results confirm a clear variation of total rate from year to year, inversely correlated with the annual sunspot number. Although meteor rates call for a density gradient variation inversely related to the solar cycle, direct evidence for such a variation remains nonexistant. Possibly the effect is being obscured by other density changes occurring at these heights. Analysis of meteor rates within the same one-year period in the two hemispheres has established that seasonal rate changes brought about by the variation of the angle between the latitude of the observing station and the apex of the earth's way override change of density gradient in at least one of the hemispheres and possibly both in controlling meteor rates within the year.