Title: Interactions between the 11-year solar cycle and the QBO in a zonally averaged two-dimensional dynamical-photochemical model
Author: John P. McCormack
Affil: Naval Research Laboratory, Washington DC
Email: mccormack@uap2.nrl.navy.mil
Authors: David E. Siskind
Affils: Naval Research Laboratory, Washington DC
Abstract: Variations in solar ultraviolet (UV) flux over the 11-year solar cycle have a direct effect on the distribution of ozone and temperature in the upper stratosphere (40-50 km altitude). There now exists a considerable body of observational evidence indicating a relationship between these variations in solar UV flux and periodic climate signals in the troposphere and lower stratosphere (below 30 km altitude). Although the physical mechanism(s) relating the higher altitude variations to the lower altitude climatic signal remain(s) to be determined, one possible explanation involves a feedback mechanism in which the initial perturbation to the upper stratosphere triggers a change in the wave driving of the stratospheric meridional circulation. This in turn could alter the wave-driven fluxes of heat and momentum in the lower stratosphere, in effect translating the effects of the 11-year solar variations downward. Zonally averaged two-dimensional model simulations of the photochemistry and dynamics of the stratosphere are well-suited for investigating this type of feedback mechanism. Long-term model simulations including an 11-year variation in solar UV and a realistic quasi-biennial oscillation (QBO) in stratospheric winds and temperatures are presented to show how changes in stratospheric photochemistry and transport over interannual time scales impact the distributions of chemical species such as ozone, water vapor, and methane that influence the radiative balance of the climate system.