Ge. Kocharov et al., On the quasi-five-year variation of nitrate abundance in polar ice and solar flare activity in the past, SOLAR PHYS, 188(1), 1999, pp. 187-190
The quasi-five-year variation in the abundance of nitrate in Central Greenl
and ice is revealed. Probable origin of the variation is the connection of
solar proton events with the period of declining solar activity. Such a con
nection exists during more than 200 years and appears to be a fundamental p
roperty of solar activity.