Solar atmospheric coupling by electrons (SOLACE): 2. Calculated stratospheric effects of precipitating electrons, 1979–1988

Abstract

An analysis has been carried out of the effects of energetic electron precipitation (EEP) on stratospheric NO y , NO 2 , and O 3 . Solar wind observations used together with precipitating electron fluxes observed aboard TIROS spacecraft show a close relationship between the long‐ and short‐term fluctuations in the solar wind and EEP over a period of 16 years. Daily electron energy spectra for 4.25≤E≤1050 keV and energy deposition profiles are developed for both hemispheres for L≥5 and used in two‐dimensional chemical transport simulations for the period January 15, 1979, through December 31, 1987. Results indicate that globally averaged column NO y (from 25 to 40 km) increases by ≈ 12% between 1979 and 1983–1985 with a rapid decline to 1979 levels between early 1985 and 1987. Day‐by‐day comparisons of the results with the Stratospheric Aerosol and Gas Experiment (SAGE II) column NO 2 and O 3 for the period October 24, 1984, and December 31, 1987, show good agreement with the inclusion of EEP in the simulations. Northern near‐hemispheric decreases of column NO 2 of ≈ 35% observed by SAGE II between early 1985 and 1987 are well simulated with the inclusion of EEP. Comparisons of several simulations with one another and with SAGE II NO 2 data and Solar Backscattered Ultraviolet (SBUV) (V6) O 3 data suggest that SOLACE represents a solar‐ terrestrial coupling mechanism which, for solar cycle 21, is as important to stratospheric O 3 as solar UV flux variations.