PERIODIC VARIATIONS OF SOLAR-RADIATION - POSSIBLE SOURCE OF SOLAR ACTIVITY WEATHER EFFECTS

It is suggested that long-lasting co-rotating active longitudes on the Sun may be associated with small variations of the solar radiation reaching the Earth. The oscillations have a basic period of about 27 days and are not expected to have amplitudes greater than 0.1%. They result in a time-varying heat input to the Earth's continents and, since the land exchanges heat with the overlying atmosphere, this oscillatory heating process generates large-scale planetary waves, mainly of the Rossby-Haurwitz type, in the atmosphere. The prevailing westerly wind in the troposphere modifies the height structure and the meridional structure of these waves and leads to pressure oscillations with zonal wave-numbers zero, one and two and having amplitudes that should be readily detectable. © 1979.