Nf. Arnold et Tr. Robinson, SOLAR-CYCLE CHANGES TO PLANETARY WAVE-PROPAGATION AND THEIR INFLUENCEON THE MIDDLE ATMOSPHERE CIRCULATION, Annales geophysicae, 16(1), 1998, pp. 69-76
Recent observations suggest that there may be a causal relationship be
tween solar activity and the strength of the winter Northern Hemispher
e circulation in the stratosphere. A three-dimensional model of the at
mosphere between 10-140 km was developed to assess the influence of so
lar minimum and solar maximum conditions on the propagation of planeta
ry waves and the subsequent changes to the circulation of the stratosp
here. Ultraviolet heating in the middle atmosphere was kept constant i
n order to emphasise the importance of non-linear dynamical coupling.
A realistic thermosphere was achieved by relaxing the upper layers to
the MSIS-90 empirical temperature model. In the summer hemisphere, str
ong radiative damping prevents significant dynamical coupling from tak
ing place. Within the dynamically controlled winter hemisphere, small
perturbations are reinforced over long periods of time, resulting in s
ystematic changes to the stratospheric circulation. The winter vortex
was significantly weakened during solar maximum and western phase of t
he quasi-biennial oscillation, in accordance with reported 30 mb geopo
tential height and total ozone measurements.