{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T18:51:17Z","timestamp":1783104677801,"version":"3.54.6"},"reference-count":44,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2021,12,21]],"date-time":"2021-12-21T00:00:00Z","timestamp":1640044800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Major advancements in the monitoring of both the occurrence and impacts of space weather can be made by evaluating the occurrence and distribution of ionospheric disturbances. Previous studies have shown that the fluctuations in total electron content (TEC) values estimated from Global Navigation Satellite System (GNSS) observations clearly exhibit the intensity levels of ionospheric irregularities, which vary continuously in both time and space. The duration and intensity of perturbations depend on the geographic location. They are also dependent on the physical activities of the Sun, the Earth\u2019s magnetic activities, as well as the process of transferring energy from the Sun to the Earth. The aim of this study is to establish ionospheric irregularity maps using ROTI (rate of TEC index) values derived from conventional dual-frequency GNSS measurements (30-s interval). The research areas are located in Southeast Asia (15\u00b0S\u201325\u00b0N latitude and 95\u00b0E\u2013115\u00b0E longitude), which is heavily affected by ionospheric scintillations, as well as in other regions around the globe. The regional ROTI map of Southeast Asia clearly indicates that ionospheric disturbances in this region are dominantly concentrated around the two equatorial ionization anomaly (EIA) crests, occurring mainly during the evening hours. Meanwhile, the global ROTI maps reveal the spatial and temporal distributions of ionospheric scintillations. Within the equatorial region, South America is the most vulnerable area (22.6% of total irregularities), followed by West Africa (8.2%), Southeast Asia (4.7%), East Africa (4.1%), the Pacific (3.8%), and South Asia (2.3%). The generated maps show that the scintillation occurrence is low in the mid-latitude areas during the last solar cycle. In the polar regions, ionospheric irregularities occur at any time of the day. To compare ionospheric disturbances between regions, the Earth is divided into ten sectors and their irregularity coefficients are calculated accordingly. The quantification of the degrees of disturbance reveals that about 58 times more ionospheric irregularities are observed in South America than in the southern mid-latitudes (least affected region). The irregularity coefficients in order from largest to smallest are as follows: South America, 3.49; the Arctic, 1.94; West Africa, 1.77; Southeast Asia, 1.27; South Asia, 1.24; the Antarctic, 1.10; East Africa, 0.89; the Pacific, 0.32; northern mid-latitudes, 0.15; southern mid-latitudes, 0.06.<\/jats:p>","DOI":"10.3390\/rs14010010","type":"journal-article","created":{"date-parts":[[2021,12,21]],"date-time":"2021-12-21T09:50:43Z","timestamp":1640080243000},"page":"10","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Spatial and Temporal Distributions of Ionospheric Irregularities Derived from Regional and Global ROTI Maps"],"prefix":"10.3390","volume":"14","author":[{"given":"Chinh Thai","family":"Nguyen","sequence":"first","affiliation":[{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"},{"name":"Department of Geodesy, Faculty of Geomatics and Land Administration, Hanoi University of Mining and Geology, Hanoi 100000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5771-0703","authenticated-orcid":false,"given":"Seun Temitope","family":"Oluwadare","sequence":"additional","affiliation":[{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nhung Thi","family":"Le","sequence":"additional","affiliation":[{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"},{"name":"Faculty of Surveying, Mapping and Geographic Information, Hanoi University of Natural Resources and Environment, Hanoi 100000, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5721-5561","authenticated-orcid":false,"given":"Mahdi","family":"Alizadeh","sequence":"additional","affiliation":[{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"},{"name":"Faculty of Geodesy and Geomatics Engineering, K. N. Toosi University of Technology, Tehran 19697, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jens","family":"Wickert","sequence":"additional","affiliation":[{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"},{"name":"Institute of Geodesy and Geoinformation Science, Technische Universit\u00e4t Berlin, 10623 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5443-0370","authenticated-orcid":false,"given":"Harald","family":"Schuh","sequence":"additional","affiliation":[{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"},{"name":"Institute of Geodesy and Geoinformation Science, Technische Universit\u00e4t Berlin, 10623 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"282","DOI":"10.1016\/j.asr.2018.08.044","article-title":"Characterization of GPS-TEC over African equatorial ionization anomaly (EIA) region during 2009\u20132016","volume":"63","author":"Oluwadare","year":"2018","journal-title":"Adv. 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