{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,13]],"date-time":"2026-01-13T21:29:25Z","timestamp":1768339765160,"version":"3.49.0"},"reference-count":51,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2023,10,9]],"date-time":"2023-10-09T00:00:00Z","timestamp":1696809600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["42274040"],"award-info":[{"award-number":["42274040"]}]},{"name":"Specialized Research Fund for State Key Laboratories","award":["42274040"],"award-info":[{"award-number":["42274040"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>In this paper, GNSS stations\u2019 observational data, global ionospheric maps (GIM) and the electron density of FORMOSAT-7\/COSMIC-2 occultation are used to study ionospheric anomalies before the submarine volcanic eruption of Hunga Tonga\u2013Hunga Ha\u2019apai on 15 January 2022. (i) We detect the negative total electron content (TEC) anomalies by three GNSS stations on 5 January before the volcanic eruption after excluding the influence of solar and geomagnetic disturbances and lower atmospheric forcing. The GIMs also detect the negative anomaly in the global ionospheric TEC only near the epicenter of the eruption on 5 January, with a maximum outlier exceeding 6 TECU. (ii) From 1 to 3 January (local time), the equatorial ionization anomaly (EIA) peak shifts significantly towards the Antarctic from afternoon to night. The equatorial ionization anomaly double peak decreases from 4 January, and the EIA double peak disappears and merges into a single peak on 7 January. Meanwhile, the diurnal maxima of TEC at TONG station decrease by nearly 10 TECU and only one diurnal maximum occurred on 4 January (i.e., 5 January of UT), but the significant ionospheric diurnal double-maxima (DDM) are observed on other dates. (iii) We find a maximum value exceeding NmF2 at an altitude of 100~130 km above the volcanic eruption on 5 January (i.e., a sporadic E layer), with an electron density of 7.5 \u00d7 105 el\/cm3.<\/jats:p>","DOI":"10.3390\/rs15194879","type":"journal-article","created":{"date-parts":[[2023,10,9]],"date-time":"2023-10-09T05:07:13Z","timestamp":1696828033000},"page":"4879","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Analysis of Ionospheric Anomalies before the Tonga Volcanic Eruption on 15 January 2022"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0054-6690","authenticated-orcid":false,"given":"Jiandi","family":"Feng","sequence":"first","affiliation":[{"name":"School of Civil Engineering and Geomatics, Shandong University of Technology, Zibo 255000, China"},{"name":"State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190, China"}]},{"given":"Yunbin","family":"Yuan","sequence":"additional","affiliation":[{"name":"Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1386-8795","authenticated-orcid":false,"given":"Ting","family":"Zhang","sequence":"additional","affiliation":[{"name":"Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China"}]},{"given":"Zhihao","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Geomatics, Shandong University of Technology, Zibo 255000, China"}]},{"given":"Di","family":"Meng","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Geomatics, Shandong University of Technology, Zibo 255000, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1250","DOI":"10.1029\/JZ070i005p01250","article-title":"Observation of ionospheric disturbances following the Alaska earthquake","volume":"70","author":"Leonard","year":"1965","journal-title":"J. Geophys. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"632","DOI":"10.1126\/science.180.4086.632","article-title":"Earthquake Prediction: Variation of Seismic Velocities before the San Francisco Earthquake","volume":"180","author":"Whitcomb","year":"1973","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"413","DOI":"10.3319\/TAO.2004.15.3.413(EP)","article-title":"Ionospheric Precursors of Earthquakes; Recent Advances in Theory and Practical Applications","volume":"15","author":"Pulinets","year":"2004","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3602","DOI":"10.1002\/2017JA023921","article-title":"Preseismic ionospheric anomalies detected before the 2016 Kumamoto earthquake","volume":"122","author":"Iwata","year":"2017","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"e2020JA028761","DOI":"10.1029\/2020JA028761","article-title":"Detecting Seismo-Ionospheric Anomalies Possibly Associated with the 2019 Ridgecrest (California) Earthquakes by GNSS, CSES, and Swarm Observations","volume":"126","author":"Xie","year":"2021","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1007\/s10950-015-9516-x","article-title":"Statistical analysis of seismo-ionospheric anomalies related to Ms > 5.0 earthquakes in China by GPS TEC","volume":"20","author":"Ke","year":"2016","journal-title":"J. Seismol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"L17312","DOI":"10.1029\/2011GL047908","article-title":"Ionospheric electron enhancement preceding the 2011 Tohoku-Oki earthquake","volume":"38","author":"Heki","year":"2011","journal-title":"Geophys. Res. Lett."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Le, H., Liu, J.Y., and Liu, L. (2011). A statistical analysis of ionospheric anomalies before 736 M6.0+ earthquakes during 2002\u20132010. J. Geophys. Res. Space Phys., 116.","DOI":"10.1029\/2010JA015781"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"B02202","DOI":"10.1029\/2008JB005722","article-title":"Global Positioning System detection and energy estimation of the ionospheric wave caused by the 13 July 2003 explosion of the Soufri\u00e8re Hills Volcano, Montserrat","volume":"114","author":"Dautermann","year":"2009","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1016\/j.epsl.2015.11.029","article-title":"Atmospheric resonant oscillations by the 2014 eruption of the Kelud volcano, Indonesia, observed with the ionospheric total electron contents and seismic signals","volume":"434","author":"Nakashima","year":"2016","journal-title":"Earth Planet. Sci. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2836","DOI":"10.1016\/j.asr.2017.07.007","article-title":"Atmospheric-ionospheric disturbances following the April 2015 Calbuco volcano from GPS and OMI observations","volume":"60","author":"Liu","year":"2017","journal-title":"Adv. Space Res."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1146\/annurev.fluid.39.050905.110207","article-title":"The Fluid Mechanics Inside a Volcano","volume":"39","author":"Gonnermann","year":"2006","journal-title":"Annu. Rev. Fluid Mech."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1265","DOI":"10.1029\/2019RG000668","article-title":"Ionospheric Detection of Natural Hazards","volume":"57","author":"Astafyeva","year":"2019","journal-title":"Rev. Geophys."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"L14303","DOI":"10.1029\/2006GL026249","article-title":"Explosion energy of the 2004 eruption of the Asama Volcano, central Japan, inferred from ionospheric disturbances","volume":"33","author":"Heki","year":"2006","journal-title":"Geophys. Res. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"721","DOI":"10.1029\/92GL00258","article-title":"Harmonic excitation of mantle Rayleigh waves by the 1991 eruption of Mount Pinatubo, Philippines","volume":"19","author":"Kanamori","year":"1992","journal-title":"Geophys. Res. Lett."},{"key":"ref_16","unstructured":"Kakinami, Y., Kamogawa, M., Tanioka, Y., Watanabe, S., Gusman, A.R., Liu, J.-Y., Watanabe, Y., and Mogi, T. (2012). Geophysical Research Letters, Wiely."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"10303","DOI":"10.1002\/2016JA023382","article-title":"Ionospheric detection and localization of volcano eruptions on the example of the April 2015 Calbuco events","volume":"121","author":"Shults","year":"2016","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"GI2002","DOI":"10.1029\/2004GI000092","article-title":"Localization of the source of ionospheric disturbance generated during an earthquake","volume":"6","author":"Afraimovich","year":"2006","journal-title":"Int. J. Geomagn. Aeron."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1016\/j.geog.2015.01.003","article-title":"Ionospheric total electron content disturbance associated with May 12, 2008, Wenchuan earthquake","volume":"6","author":"Li","year":"2015","journal-title":"Geod. Geodyn."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.jvolgeores.2016.06.017","article-title":"Total electron content anomalies associated with global VEI4+ volcanic eruptions during 2002\u20132015","volume":"325","author":"Li","year":"2016","journal-title":"J. Volcanol. Geotherm. Res."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Zhou, M., Gao, H., Yu, D., Guo, J., Zhu, L., Yang, L., and Pan, S. (2022). Analysis of the Anomalous Environmental Response to the 2022 Tonga Volcanic Eruption Based on GNSS. Remote Sens., 14.","DOI":"10.3390\/rs14194847"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e2022GL098577","DOI":"10.1029\/2022GL098577","article-title":"Impacts of the January 2022 Tonga Volcanic Eruption on the Ionospheric Dynamo: ICON-MIGHTI and Swarm Observations of Extreme Neutral Winds and Currents","volume":"49","author":"Harding","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"e2022GL100555","DOI":"10.1029\/2022GL100555","article-title":"Oscillations of the Ionosphere Caused by the 2022 Tonga Volcanic Eruption Observed With SuperDARN Radars","volume":"49","author":"Zhang","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e2022JA030527","DOI":"10.1029\/2022JA030527","article-title":"Pronounced Suppression and X-Pattern Merging of Equatorial Ionization Anomalies after the 2022 Tonga Volcano Eruption","volume":"127","author":"Aa","year":"2022","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"e2022GL098827","DOI":"10.1029\/2022GL098827","article-title":"The 15 January 2022 Hunga Tonga eruption history as inferred from ionospheric observations","volume":"49","author":"Astafyeva","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"e2022GL098222","DOI":"10.1029\/2022GL098222","article-title":"Rapid Conjugate Appearance of the Giant Ionospheric Lamb Wave Signatures in the Northern Hemisphere After Hunga-Tonga Volcano Eruptions","volume":"49","author":"Lin","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1186\/s40623-022-01674-7","article-title":"Ionospheric signatures of repeated passages of atmospheric waves by the 2022 Jan. 15 Hunga Tonga-Hunga Ha\u2019apai eruption detected by QZSS-TEC observations in Japan","volume":"74","author":"Heki","year":"2022","journal-title":"Earth Planets Space"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"e2022GL099163","DOI":"10.1029\/2022GL099163","article-title":"Detection of Different Properties of Ionospheric Perturbations in the Vicinity of the Korean Peninsula After the Hunga-Tonga Volcanic Eruption on 15 January 2022","volume":"49","author":"Hong","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"e2022GL100145","DOI":"10.1029\/2022GL100145","article-title":"Spectral Characteristics of Ionospheric Disturbances Over the Southwestern Pacific from the 15 January 2022 Tonga Eruption and Tsunami","volume":"49","author":"Ghent","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"e2022GL098158","DOI":"10.1029\/2022GL098158","article-title":"Global Propagation of Ionospheric Disturbances Associated with the 2022 Tonga Volcanic Eruption","volume":"49","author":"Themens","year":"2022","journal-title":"Geophys. Res. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1186\/s40623-022-01619-0","article-title":"Ionospheric disturbances observed over Japan following the eruption of Hunga Tonga-Hunga Ha\u2019apai on 15 January 2022","volume":"74","author":"Saito","year":"2022","journal-title":"Earth Planets Space"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1051\/swsc\/2020030","article-title":"Impact of medium-scale traveling ionospheric disturbances on network real-time kinematic services: CATNET study case","volume":"10","author":"Juan","year":"2020","journal-title":"J. Space Weather. Space Clim."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"e2019JA027681","DOI":"10.1029\/2019JA027681","article-title":"Global View of Ionospheric Disturbance Impacts on Kinematic GPS Positioning Solutions during the 2015 St. Patrick\u2019s Day Storm","volume":"125","author":"Yang","year":"2020","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_34","first-page":"e2023SW003476","article-title":"The ionospheric effects of the 2022 Hunga Tonga Volcano eruption and the associated impacts on GPS Precise Point Positioning across the Australian region","volume":"21","author":"Carter","year":"2023","journal-title":"ESS Open Arch."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"A11","DOI":"10.1029\/2007JA012459","article-title":"Total Electron Content Estimation with Reg-Est","volume":"112","author":"Nayir","year":"2007","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1002\/swe.20054","article-title":"Online, automatic, near-real time estimation of GPS-TEC: IONOLAB-TEC","volume":"11","author":"Sezen","year":"2013","journal-title":"Space Weather.-Int. J. Res. Appl."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"A8","DOI":"10.1029\/2003JA010342","article-title":"Global dayside ionospheric uplift and enhancement associated with interplanetary electric fields","volume":"109","author":"Tsurutani","year":"2004","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1978","DOI":"10.1016\/j.asr.2017.07.010","article-title":"Study of ionospheric precursors using GPS and GIM-TEC data related to earthquakes occurred on 16 April and 24 September, 2013 in Pakistan region","volume":"60","author":"Pundhir","year":"2017","journal-title":"Adv. Space Res."},{"key":"ref_39","unstructured":"Triebe, O., Hewamalage, H., Pilyugina, P., Laptev, N.P., Bergmeir, C., and Rajagopal, R. (2021). NeuralProphet: Explainable Forecasting at Scale. arXiv."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"561","DOI":"10.5194\/npg-11-561-2004","article-title":"Application of the cross wavelet transform and wavelet coherence to geophysical time series","volume":"11","author":"Grinsted","year":"2004","journal-title":"Nonlin. Process. Geophys."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Yang, Z., Gu, S.-Y., Qin, Y., Teng, C.-K.-M., Wei, Y., and Dou, X. (2022). Ionospheric Oscillation with Periods of 6&ndash;30 Days at Middle Latitudes: A Response to Solar Radiative, Geomagnetic, and Lower Atmospheric Forcing. Remote Sens., 14.","DOI":"10.3390\/rs14225895"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3217","DOI":"10.1029\/2017JA025166","article-title":"Was Magnetic Storm the Only Driver of the Long-Duration Enhancements of Daytime Total Electron Content in the Asian-Australian Sector between 7 and 12 September 2017?","volume":"123","author":"Lei","year":"2018","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_43","first-page":"A4","article-title":"Observations and simulations of seismoionospheric GPS total electron content anomalies before the 12 January 2010 M7 Haiti earthquake","volume":"116","author":"Liu","year":"2011","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/0032-0633(71)90205-4","article-title":"The F-layer dynamo","volume":"19","author":"Rishbeth","year":"1971","journal-title":"Planet. Space Sci."},{"key":"ref_45","unstructured":"Martyn, D. (1955). Theory of height and ionization density changes at the maximum of a Chapman-like region, taking account of ion production, decay, diffusion and tidal drift. Phys. Ionos., 254."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"L19101","DOI":"10.1029\/2007GL030741","article-title":"Motions of the equatorial ionization anomaly crests imaged by FORMOSAT-3\/COSMIC","volume":"34","author":"Lin","year":"2007","journal-title":"Geophys. Res. Lett."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"7166","DOI":"10.1002\/2016JA022394","article-title":"Equatorial ionization anomaly in the low-latitude topside ionosphere: Local time evolution and longitudinal difference","volume":"121","author":"Chen","year":"2016","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"5949","DOI":"10.1029\/2018JA025469","article-title":"The Response Time of Equatorial Ionization Anomaly Crest: A Unique Precursor to the Time of Equatorial Spread F Initiation","volume":"123","author":"Aswathy","year":"2018","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"e2022JA030706","DOI":"10.1029\/2022JA030706","article-title":"Hemispherically Asymmetric Evolution of Nighttime Ionospheric Equatorial Ionization Anomaly in the American Longitude Sector","volume":"127","author":"Cai","year":"2022","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/0021-9169(89)90122-0","article-title":"Recent work on mid-latitude and equatorial sporadic-E","volume":"51","author":"Whitehead","year":"1989","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"A9","DOI":"10.1029\/2008JA013158","article-title":"On blanketing sporadic E and polarization effects near the equatorial electrojet","volume":"113","author":"Tsunoda","year":"2008","journal-title":"J. Geophys. Res. Space Phys."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/19\/4879\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:03:17Z","timestamp":1760130197000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/19\/4879"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,9]]},"references-count":51,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2023,10]]}},"alternative-id":["rs15194879"],"URL":"https:\/\/doi.org\/10.3390\/rs15194879","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,10,9]]}}}