Ionospheric plasma irregularities inside the mid-latitude trough by using Swarm observations

The mid-latitude ionospheric trough (MIT) is a well-known feature in the topside ionosphere and plasmasphere. In this report, we investigated the plasma irregularities inside the MIT region based on the high-resolution (2 Hz) measurements of electron density and temperature from the Swarm satellite. We developed a method to automatically identify the mid-latitude trough from Swarm in-situ density measurements, and the small-scale irregularities inside MIT region can also be well determined by considering appropriate thresholds of both the relative (∆Ne/Ne) and absolute (∆Ne) density fluctuations. Further statistics has been performed based-on the multi-years database of identified MITs and irregularities from Swarm. Finally, we provided for the first time the seasonal and magnetic local time distributions of irregularities within the MIT region, and the involved plasma instabilities that cause the irregularities at the MIT region have been discussed.