Page 7 - NCU Newsletter - NO23

“ Enormous Variations in the Ionospheric Amplitude Caused by ” the Moon’s Gravitational Force: A Significant Discovery by NCU’s Space Science Research Team Professor Liu Jann-Yenq, Dr. Wu Tsung-Yu, Dr. Lin Chi-Yen, and Professor Chang Chi-Wei published the article“The Three-dimensional Plasma Structures and Flows of the Earth’s Upper Atmosphere Due to the M o o n ’s G r a v i t a t i o n a l F o r c e ” o n t h e w o r l d ’s t o p j o u r n a l Scientific Reports. They fully utilized the data of radio occultation collected by the satellites FORMOSAT- and FORMOSAT- for the past years, analyzing the three-dimensional structures of the global ionosphere and the lunar tide effect cast upon it by the moon’s gravitational force. Their discovery was unprecedent- ed. For thousands of years, humans have known the rise and fall of sea levels, and such a natural phenomenon is called the tide, which is caused by lunar gravity. The research team led by Professor Liu Jann-Yenq further discovered that the amplitude of the ionosphere also has such high and low tides. The team collected the radio occultation data from FORMOSAT- and FORMO- SAT- satellites and analyzed the three-dimensional structures of the ionosphere. They discovered that the moon’s pull can cause the amplitude of the global ionosphere to fluctuate between and km, and the amplitude of the ionospheric tides can be a thousand times larger than that of the sea tides. Sea tides on the Earth can be constrained by geographical landscapes; the features of high and low tides in different regions thus vary. However, distinct from sea tides, the lunar tides observed in the ionosphere clearly demonstrate the moon’s gravitational force, which is closer to the Photo by Lin Yen-Tsen NCU’s research team publishes its research on ionospheric amplitude change caused by the moon’s gravitational force. Figures on the left are data from the satellites FORMO- SAT-3 and FORMOSAT-7. Figures on the right demonstrate how the amplitude of the ionosphere is affected by the moon’s gravitational force. Photo courtesy of Professor Liu Jann-Yenq “FORMOSAT- and FORMOSAT- are the satellites developed in the collaborative research project by Taiwan and the United States, aiming to build a highly reliable mission-oriented meteorological satellite system. By receiving signals from the Global Naviga- tion Satellite System (GNSS), the satellites can collect data on atmospheric pressure, temperature, humidity, and the vertical distribution of the ionosphere's elec- tron density. The observation range covers the whole world. Thanks to the densely accumulated observation data; we could thus successfully discover the three-di- mensional tidal phenomenon of the global iono- sphere,”said Professor Liu Jann-Yenq. ACADEMIC RESEARCH AND DEVELOPMENT 05