Photochemical response of neutral and ionized middle atmosphere composition to the strong solar proton event of October 1989

One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middle atmosphere chemistry including ionized components in the D-region is examined. The ionization rate, and ozone, NO and OH density temporal and spatial (vertical) deviations induced by the SPE, calculated by a 1-D time-dependent photochemical model separately for daytime and nighttime (not shown here), are used in a 1-D model of the lower ionosphere to calculate the response of ionized components to combined forcing by ionization rate and neutral chemical composition disturbances. The radio wave absorption caused by electron density disturbances after the SPE is calculated and compared with observations. The computed ozone values are compared with observations, as well.