EVIDENCE FOR POLARIZATION ELECTRIC-FIELDS IN THE DAYTIME F-REGION ABOVE MILLSTONE-HILL

Persistent anticorrelations between the ion drift components V(perpendicular-to N) and V(parallel-to) are seen in the daytime F region near solar maximum above Millstone Hill. The possibility that all of these anticorrelations may be spurious has been ruled out by calculating the correlations and anticorrelations which are introduced by simply adding random errors to the line-of-sight velocity measurements for each experiment considered. Variations in h(m)F2 follow V(parallel-to) during most of these intervals, suggesting that a neutral wind causes the h(m)F2 variations and is responsible for the anticorrelations between V(perpendicular-to N) and V(parallel-to) by setting up polarization electric fields by the wind dynamo mechanism. It is widely believed that such F region polarization electric fields cannot occur or are very weak during the daytime, as they are shorted out by the E region conductivity. However, calculations of the E and F region Pedersen conductivities using Millstone Hill electron density profiles and the mass spectrometer/incoherent scatter (MSIS) 86 model show how the F region Pedersen conductivities increase from solar minimum to solar maximum, so that the height-integrated Pedersen conductivities are larger in the F region than in the E region under winter daytime conditions at solar maximum. Thus the E region conductivity is not capable of fully shorting out the F region polarization electric fields above Millstone Hill during daytime at solar maximum. These are apparently the first calculations of ionospheric conductivities above Millstone Hill using incoherent scatter electron density profiles.