Ac. Aikin, PRODUCTION OF STRATOSPHERIC HNO3 BY DIFFERENT ION-MOLECULE REACTION-MECHANISMS, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102(11D), 1997, pp. 12921-12925
Precipitation of energetic charged particles into the polar winter str
atosphere leads to an enhancement of nitric acid. Three different ion-
molecule reaction mechanisms have been suggested as the cause of the H
NO3 enhancement: 1) OH production by ion-molecule reactions and subseq
uent reaction with NO2 to produce HNO3, 2) positive ion-negative ion r
ecombination, and 3) positive hydrated ion reaction with N2O5. It is s
hown that the OH reaction can be disregarded. While H+(H2O)(n) + N2O5
may be important below 40 km, it accounts for less than half the HNO3
production at 45 km and is negligible in comparison with ion-ion recom
bination at higher altitudes. The inclusion of ion-ion recombination g
reatly reduces the ion pair production requirements for HNO3 productio
n.