HAO Colloquium - Min-Yang Chou, COSMIC

Space weather links to natural and anthropogenic events

The Earth’s ionosphere consists of a great number of electrically charged particles which is strongly affected by solar and geomagnetic forcing. Under the quiet geomagnetic conditions, geophysical and meteorological events on Earth, such as earthquake, tsunami, typhoon, and tornado, are considered to be another branch to affect the ionosphere. These natural events can generate atmospheric gravity waves propagating upward into the ionosphere, triggering ionospheric disturbances and irregularities that may introduce errors into the positioning and navigation for the Global Navigation Satellite Systems. On the other hands, rapid developments in space technology have enabled human exploration beyond the Earth’s orbit. A great number of space vehicles carrying payloads into orbits also cause changes to the adjacent space environment. 

In this talk, I will first present the ionospheric responses to the natural event: super typhoon. Two Category 5 Super Typhoon Meranti and Nepartak swept toward Taiwan in 2016 and triggered unprecedented concentric ripples in the ionosphere. These ionospheric ripples are the manifestation of typhoon-induced concentric gravity waves in the ionosphere. Gravity wave perturbations in the ionosphere affect the ionospheric electrodynamics, leading to the ionospheric instabilities in the low-latitude ionosphere. It is suggested that gravity wave-driven wind perturbations could produce dynamo currents to affect the ionospheric electrodynamics, coupling with the Perkins instability to trigger the ionospheric instabilities. The NRL SAMI3/ESF model is further used to confirm the interconnection between the concentric gravity waves and Perkins instability. 

Next, I will present the ionosphere variability in response to three SpaceX rocket launches (Jason-3, Formosat-5, and Falcon Heavy missions). In GNSS TEC observations, we found that the rocket launches can be another source to trigger ionospheric disturbances by atmospheric waves. Large amounts of rocket exhaust into the ionosphere also cause plasma depletions, resulting in a gigantic plasma hole in the ionosphere. We also found that rocket with different trajectory and attitude during orbit insertion could cause ionospheric perturbations with different morphology. These results demonstrate that the man-made space weather will become an important issue as these anthropogenic space weather events are expected to increase at an enormous rate in the near future.   

Date and time: 
Wednesday, May 22, 2019 - 2:00pm to 3:00pm