Tropospheric circulation and interplanetary magnetic sector boundaries followed by MeV proton streams

Abstract

TRANSITS of some interplanetary magnetic sector boundaries across the Earth were shown by Svestka et al.1 to be followed by streams of protons with energies in the range of a few MeV. These proton boundary transits were associated with a characteristic decrease2–4 of the vorticity area index (VAI) during Northern Hemisphere winter that was about twice as large as the decrease associated with all the other boundary transits during the same interval. I show here that the MeV proton streams associated by Svestka et al.1 with certain sector boundary transits apparently select boundary transits associated with unusually active conditions in the solar wind. These proton boundary transits were associated with a larger change in tropospheric circulation than were the other boundary transits observed during the same interval of time. New information in the present study of sector boundary transits relating changes in solar wind velocity, density and magnetic field to the resulting terrestrial changes in vorticity area index, geomagnetic activity and cosmic ray flux at Earth may provide a test for proposed physical mechanisms.