Coupling Between E Region Quasi‐Periodic Echoes and F Region Medium‐Scale Traveling Ionospheric Disturbances at Low Latitudes

Abstract

AbstractE region quasi‐periodic (QP) echoes from a VHF coherent backscatter radar, sporadic E (Es) layer from a digisonde, and F region medium‐scale traveling ionospheric disturbances (MSTIDs) from global navigation satellite systems receivers were simultaneously observed at low latitudes. The results on the night of 3 March 2018 show that the QP echoes in radar height‐time intensity maps were clustered into groups, coinciding with the periods of MSTIDs and strong Es layer. The MSTIDs had phase fronts elongating in the northwest‐southeast direction and propagated southwestward from middle to low latitudes. Similar to the propagation direction of MSTIDs, the low‐latitude Es layers also propagated southwestward. For the QP echoing clusters, a westward drift was seen from the radar multibeam observations. The Doppler velocities of QP echoes show beam dependence, with significantly enhanced positive values (motion away from the radar) in the westernmost beam. Based on a preliminary statistical analysis during the period March–June 2018, it was found that out of a total of 102 nights, there are 32 nights when QP echoes were generated. The simultaneous occurrences of QP echoes and MSTIDs were observed on six nights. We suggest that when the MSTIDs coming from middle latitudes approach low latitudes, the polarization electric fields associated with the MSTIDs could modulate the E region plasma instability producing QP echoes at low latitudes through the E‐F region electrodynamic coupling.