Formation of the Evening Time F3 Layer Investigated Using Jicamarca Incoherent Scatter Radar Observations

Abstract

AbstractThe formation of the evening time F3 layer remains elusive. One of the hypotheses for the formation of the evening time F3 layer relies on the height gradient in the vertical plasma drift. In this paper, we test the validity of the hypothesis using Jicamarca incoherent scatter radar observations of height profiles of electron density and vertical plasma drift. Results show that the evening F3 layer could occur when the plasma drift is moderate and the height gradient in the vertical plasma drift is small or insignificant. Given that the production in the evening hours is negligible, these results call for interpretation for understanding the formation of the evening F3 layer. We propose that in addition to the known role of vertical plasma drift, the height variation in the recombination loss of electrons plays an important role in the formation of evening F3 layer over the geomagnetic equator.