Low Altitude Tailing Es (LATTE): Analysis of Sporadic‐E Layer Height at Different Latitudes of Middle and Low Region.

In this paper, the Earth's sporadic‐E (Es) layer vertical motion is investigated by using an image processing technique for automatic scaling ionograms from Mohe (122.37°E, 53.50°N, dip angle 71°), Beijing (116.25°E, 40.25°N, dip angle 59°), Wuhan (114.61°E, 30.53°N, dip angle 46°) and Fuke (109.13°E, 19.52°N, dip angle 27°). Es traces descend with different periodicities, indicating tidal modulation to Es layers. Comparing winds from a combination of the Ionospheric Connection Explorer/Michelson Interferometer for Global High‐Resolution Thermospheric Imaging and meteor radar measurements with Es layers, we find that Es traces at high altitudes (above 110 km) rapidly move down in accordance with the descent of the wind shear nulls, which indicates the important role of the tides in the formation and descent of the Es layer at high altitude. The lower‐lying Es layers, however, do not descend with the wind shear null, but stay at the bottom of the E region (∼100 km) for a long time, which cannot be explained by tidal wind shear theory. In addition, the time duration of the Es layers staying at low latitudes increases with the decreasing latitude. Simulation results demonstrate that the low altitude tailing Es layer is dominated by the dramatically enhanced collision frequency at the lower height of the mesosphere and the lower thermosphere region. Plain Language Summary: Sporadic‐E (Es) layers are stochastic ionospheric plasma irregularities at ionospheric E region, which can significantly affect the propagation of radio waves in the ionosphere, hence are of particular interest for modern electronic systems such as HF/VHF communication systems, skywave over‐the‐horizon radars, and shortwave electronic reconnaissance/localization systems. The intensity and occurrence of Es layers exhibits complex variations in space and time, depending on the nature of atmospheric, solar and geomagnetic activities. Because of the highly complex behavior of the Es layer, the prediction of its occurrence has been one of the most difficult issues in space weather forecast. In this study, the image processing technique is used to investigate the vertical motion of the Es layer at different latitudes. Observational results demonstrate that the Es formation and movement at high altitudes are controlled by tides with different periods. However, at low altitudes, Es layers descend at a slow speed and stay at low altitudes for a long time. Observation and simulation results show that the formation of Es layers at higher altitude (above 110 km) is ascribed to the traditional wind shear theory, while the lower‐lying Es traces lasting for a long time is controlled by the dramatically enhanced collision frequency. Key Points: Michelson Interferometer for Global High‐Resolution Thermospheric Imaging/Ionospheric Connection Explorer and meteor radar measurements are combined to study the relationship between sporadic‐E (Es) layer and wind shearThe time duration of the Es layer staying at lower altitudes increases with decreasing latitudeSimulation driven by winds from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension model reproduces the tailing Es layer at the bottom of the E region [ABSTRACT FROM AUTHOR]