In this paper, we present a systematic study on the characteristics and evolution of the F-3 layer using the Jicamarca incoherent scatter radar (ISR) observations made during 2014-2018. These results are also compared with those obtained from collocated digisonde observations in an effort to understand the F-3 layer in more detail. The purpose of the comparison is twofold: first is to see how the digisonde observations compare with those of ISR, and second is to see to what extent our understanding on the F-3 layer is observationally complete. The basic characteristics of the F-3 layers observed by digisonde and ISR are found to compare well. When the F-3 layer becomes topside ledge, which was missed by the digisonde, ISR observations provided vital information in characterizing such F-3 layers. Importantly, the ISR capability to observe the F-3 layer irrespective of its density being lower or higher than that of the F-2 layer could help understand the evolution of F-3 layer. The occurrence statistics show two distinct maxima, one centered on 11:00 LT and the other centered on 18:00 LT quite consistent with earlier report. While the first peak is found to be consistent with model prediction, we suggest that the second peak is governed by quiet time height varying zonal electric field linked with sunset electrodynamics. Results presented and discussed here based on ISR observations are first of its kind and reveal the behavior and evolution of the F-3 layer not reported before.
展开▼
