E region radar echoes from low‐latitude field‐aligned irregularities due to gravity waves and tides: A case study using radar, lidar, and radiosonde observations and simulations

摘要: On the night of 5 February 2011, height-time plot echo from E region field-aligned irregularities (FAI) received by Indian mesosphere-stratosphere-troposphere radar at Gadanki (13.5°N, 79.2°E) shows a slow-descending layered structures separated nearly 8 km in height 80–100 km and vertically elongated with quasiperiodic variations higher heights. The stratospheric thermal structure also similar slowly descending separation. Hodograph 7–9 km band-pass filtered radiosonde zonal meridional winds over form clearly an ellipse, dominant period obtained ratio major to minor axes ellipse is 24 h indicating presence nonmigrating diurnal tide vertical wavelength 8 km. two-dimensional spectrum temperature perturbations, which are assumed be due gravity waves, periods near 1 h 1.5 h. FAI periods. Altitude-time cross section ion velocity computed using composed observed wave tidal parameters. As Tirunelveli (8.7°N, 77.8°E) weaker amplitudes above 90 km, removal contribution reveals slanting plasma blob heights continuous lower present study demonstrates role tides waves formation echoes respectively.