Solar interaction regions, geomagnetic indices and the troposphere

Using key dates associated with solar interaction regions (SIR), a superposed epoch analysis is performed on the zonal and meridional kinetic energy density and square of the vorticity (enstrophy) of the main motion at 500 mb height. No relationships are found between SIR and these atmospheric dynamical parameters irrespective of the polarity (North or South) of the enhanced interplanetary magnetic fields (IMF) within the SIR, or with latitude and season. This investigation and other available results suggest that the short term solar variations do not influence large volumes of the troposphere but only localized regions. The average atmospheric kinetic energy density during active solar conditions is higher than during quiet solar condition, with no significant differences in enstrophy. This confirms an earlier result. It is also shown that SIR with enhanced southward directed IMF correspond to higher level of geomagnetic index ( A_p > 10, K_p > 3) than randomly selected days.