The Effect of Solar Proton Events on Ozone and Other Constituents, in Solar Variability and Its Effects on Climate

Solar proton events(SPEs) can cause changes in constituents in the Earth's middle atmosphere. The highly energetic protons cause ionizations, excitations, dissociations, and dissociative ionizations of the background constituents. Complicated ion chemistry leads to HOx production and dissociation of N2 leads to NOy production. Both the HOx and NOy increases can result in changes to ozone in the stratosphere and mesosphere. The HOx increases lead to short-lived ozone decreases in the mesosphere and upper stratosphere due to the short lifetimes of the HO* constituents. The NOy increases lead to long-lived stratospheric ozone changes because of the long lifetime of NOy constituents this region. The NOy-induced ozone changes are generally decreases, however, the NOy constituents can interfere with chlorine and bromine radicals in the lowest part of the stratosphere and cause ozone increases. Temperature changes have been predicted to occur as a result of the larger SPEs. Atmospheric changes have been observed as a result of eleven SPEs since 1969. Neutral wind variations were measured shortly after the July 1982 and April 1984 SPEs. The recent July 2000 SPE caused NOx increases that lasted for two months past the event. The two periods of largest SPEs (August 1972 and October 1989) caused ozone decreases that lasted for several weeks past the events.