Vietnam Academy of Science and Technology

Project's information

Project's title	Study on the characteristics of low-latitude night ionosphere disturbances from DEMETER satellite and continuous GPS data in Vietnam and neighbour areas.
Project’s code	VAST05.04/20-21
Research hosting institution	Institute of Geophysics
Project leader’s name	Nguyen Chien Thang
Project duration	01/01/2020 - 30/06/2023
Project’s budget	600 million VND
Classify	Grade B
Goal and objectives of the project	To clarify the appearance of nighttime ionosphere disturbances in Southeast Asia using DEMETER satellite and continuous GPS data for the period 2005-2010.
Main results	- Theoretical results: The rapidly varying events of electron density and ion density oscillations are quasi-periodic oscillations distributed in the latitude range of about ~30o in the Southern hemisphere, and little narrower in the Northern hemisphere. The strong occurrence of this perturbation under the condition of weak magnetic activity. Statistical analysis of large-amplitude ionosphere disturbance events related to plasma bubble evolution and formation on DEMETER satellite data shows that they are centered around the geomagnetic equator with a extension in latitude which is uniform whatever the longitude and of the order of +/-15° around the magnetic equator. Seasonal variations in the observed plasma bubble perturbations show peaks at the equinoxes. From continuous GPS data, we observe an anomalous structure with two peaks on either side of the magnetic equator (at about 7-8o N latitude). The peak time is about ~7h00 UT (~14h00 LT), North peak latitude ~21o N, and South peak latitude 5-6o S, almost symmetrical about the magnetic equator. The nighttime ionosphere disturbances appear according to a distinct seasonal, the maximum frequency occurs in the equinox months higher than in the solstice months. The frequency of nighttime ionosphere disturbance at stations dependent on solar activity. The ionosphere disturbances usually appear before midnight local. According to latitude, the night ionization anomalies appear to be concentrated around the position about 4-5o latitude from the daytime equatorial ionization anomaly to the equator. - Applied results: The research results contribute information about the ionosphere anomalies in Southeast Asia to help improve the regional and global ionospheric models, improve the efficiency of using satellite signals in the Southeast Asia region and the world.
Novelty and actuality and scientific meaningfulness of the results	The distribution maps and statistical characteristics of events related to nighttime ionospheric disturbances by the years are built from DEMETER satellite data for the period 2005-2010. The project has built a software and database related to the implementation process and the results of the project including plasma parameters such as electron density data, O+ molecular ion density along the night orbit from DEMETER satellite. The software is built on the web based on Microsoft's ASP programming language, runs on a Windows server with IIS, Internet Information Services.
Products of the project	- Scientific papers in referred journals (list): [1]. Nguyen Thanh, Dung, Minh Le Huy, Christine Amory-Mazaudier, Rolland Fleury, Susumu Saito, Thang Nguyen Chien, Hong Pham Thi Thu, Thanh Le Truong, and Mai Nguyen Thi. (2021). Characterization of Ionospheric Irregularities over Vietnam and Adjacent Region for the 2008-2018 Period, Vietnam Journal of Earth Sciences, 43(4), 465-84. https://doi.org/10.15625/2615-9783/16502. [2]. Nguyen, C. T., Berthelier, J.-J., Petitdidier, M., Amory-Mazaudier, C., & Le Huy, M. (2022). Climatology of nighttime medium-scale traveling ionospheric disturbances at mid and low latitudes observed by the DEMETER satellite in the topside ionosphere during the period 2005–2010. Journal of Geophysical Research: Space Physics, 127, e2022JA030517. https://doi.org/10.1029/2022JA030517 - Technological products (describe in details: technical characteristics, place): + The database of plasma parameters from DEMETER satellite, GPS data in Vietnam and in Southeast Asia for the period 2005-2010. The software allows searching and rendering search results + Distribution maps and statistical characteristics of events related to nighttime ionosphere disturbances for each year from DEMETER satellite for the period 2005-2010. + The monthly average TEC maps of time and latitude in Southeast Asia for the period 2005-2010.
Research area	Provide scientific database for specialized research facilities on geomagnetism-ionosphere.
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