{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T18:50:03Z","timestamp":1776797403870,"version":"3.51.2"},"reference-count":56,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2024,6,9]],"date-time":"2024-06-09T00:00:00Z","timestamp":1717891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["42025404"],"award-info":[{"award-number":["42025404"]}]},{"name":"National Natural Science Foundation of China","award":["42188101"],"award-info":[{"award-number":["42188101"]}]},{"name":"National Natural Science Foundation of China","award":["41874195"],"award-info":[{"award-number":["41874195"]}]},{"name":"National Natural Science Foundation of China","award":["42274205"],"award-info":[{"award-number":["42274205"]}]},{"name":"National Natural Science Foundation of China","award":["42130210"],"award-info":[{"award-number":["42130210"]}]},{"name":"National Natural Science Foundation of China","award":["2022YFF0503700"],"award-info":[{"award-number":["2022YFF0503700"]}]},{"name":"National Natural Science Foundation of China","award":["XDB41000000"],"award-info":[{"award-number":["XDB41000000"]}]},{"name":"National Natural Science Foundation of China","award":["220100051"],"award-info":[{"award-number":["220100051"]}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["42025404"],"award-info":[{"award-number":["42025404"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["42188101"],"award-info":[{"award-number":["42188101"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["41874195"],"award-info":[{"award-number":["41874195"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["42274205"],"award-info":[{"award-number":["42274205"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["42130210"],"award-info":[{"award-number":["42130210"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["2022YFF0503700"],"award-info":[{"award-number":["2022YFF0503700"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["XDB41000000"],"award-info":[{"award-number":["XDB41000000"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key R&amp;D Program of China","doi-asserted-by":"publisher","award":["220100051"],"award-info":[{"award-number":["220100051"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["42025404"],"award-info":[{"award-number":["42025404"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["42188101"],"award-info":[{"award-number":["42188101"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["41874195"],"award-info":[{"award-number":["41874195"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["42274205"],"award-info":[{"award-number":["42274205"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["42130210"],"award-info":[{"award-number":["42130210"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["2022YFF0503700"],"award-info":[{"award-number":["2022YFF0503700"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["XDB41000000"],"award-info":[{"award-number":["XDB41000000"]}]},{"name":"B-type Strategic Priority Program of the Chinese Academy of Sciences","award":["220100051"],"award-info":[{"award-number":["220100051"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["42025404"],"award-info":[{"award-number":["42025404"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["42188101"],"award-info":[{"award-number":["42188101"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["41874195"],"award-info":[{"award-number":["41874195"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["42274205"],"award-info":[{"award-number":["42274205"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["42130210"],"award-info":[{"award-number":["42130210"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["2022YFF0503700"],"award-info":[{"award-number":["2022YFF0503700"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["XDB41000000"],"award-info":[{"award-number":["XDB41000000"]}]},{"name":"open fund of Hubei Luojia Laboratory","award":["220100051"],"award-info":[{"award-number":["220100051"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Measurements of Very-Low-Frequency (VLF) transmitter signals have been widely used to investigate the effects of various space weather events on the D-region ionosphere, including nowcasting solar flares. Previous studies have established a method to nowcast solar flares using VLF measurements, but only using measurements from dayside propagation paths, and there remains limited focus on day\u2013night mixed paths, which are important for method applicability. Between March and May of 2022, the Sun erupted a total of 56 M-class and 6 X-class solar flares, all of which were well captured by our VLF receiver in Antarctica. Using these VLF measurements, we reexamine the capability of the VLF technique to nowcast solar flares by including day\u2013night mixed propagation paths and expanding the path coverage in longitude compared to that in previous studies. The amplitude and phase maximum changes are generally positively correlated with X-ray fluxes, whereas the time delay is negatively correlated. The curve-fitting parameters that we obtain for the X-ray fluxes and VLF signal maximum changes are consistent with those in previous studies for dayside paths, even though different instruments are used, supporting the flare-nowcasting method. Moreover, the present results show that, for day\u2013night mixed paths, the amplitude and phase maximum changes also scale linearly with the logarithm of the flare X-ray fluxes, but the level of change is notably different from that for dayside paths. The coefficients used in the flare-nowcasting method need to be updated for mixed propagation paths.<\/jats:p>","DOI":"10.3390\/rs16122092","type":"journal-article","created":{"date-parts":[[2024,6,10]],"date-time":"2024-06-10T08:49:03Z","timestamp":1718009343000},"page":"2092","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Examining the Capability of the VLF Technique for Nowcasting Solar Flares Based on Ground Measurements in Antarctica"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0336-3849","authenticated-orcid":false,"given":"Shiwei","family":"Wang","sequence":"first","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ruoxian","family":"Zhou","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3078-9562","authenticated-orcid":false,"given":"Xudong","family":"Gu","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"},{"name":"Hubei Luojia Laboratory, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0092-824X","authenticated-orcid":false,"given":"Wei","family":"Xu","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"},{"name":"Hubei Luojia Laboratory, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2448-2094","authenticated-orcid":false,"given":"Zejun","family":"Hu","sequence":"additional","affiliation":[{"name":"MNR Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Binbin","family":"Ni","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"},{"name":"Hubei Luojia Laboratory, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wen","family":"Cheng","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jingyuan","family":"Feng","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenchen","family":"Ma","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haotian","family":"Xu","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yudi","family":"Pan","sequence":"additional","affiliation":[{"name":"Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4009-7305","authenticated-orcid":false,"given":"Bin","family":"Li","sequence":"additional","affiliation":[{"name":"MNR Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6781-6977","authenticated-orcid":false,"given":"Fang","family":"He","sequence":"additional","affiliation":[{"name":"MNR Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6325-5049","authenticated-orcid":false,"given":"Xiangcai","family":"Chen","sequence":"additional","affiliation":[{"name":"MNR Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hongqiao","family":"Hu","sequence":"additional","affiliation":[{"name":"MNR Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,6,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"A00E36","DOI":"10.1029\/2009JA014775","article-title":"A survey of ELF and VLF research on lightning-ionosphere interactions and causative discharges","volume":"115","author":"Inan","year":"2010","journal-title":"J. Geophys. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"773","DOI":"10.1029\/2000RS002395","article-title":"Total solar eclipse effects on VLF signals: Observations and modeling","volume":"36","author":"Clilverd","year":"2001","journal-title":"Radio Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1016\/j.asr.2012.04.007","article-title":"Modeling of sub-ionospheric VLF signal perturbations associated with total solar eclipse, 2009 in Indian subcontinent","volume":"50","author":"Pal","year":"2012","journal-title":"Adv. Space Res."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2831","DOI":"10.1029\/2018JA026273","article-title":"Characteristics of energetic electron precipitation estimated from simulated bremsstrahlung X-ray distributions","volume":"124","author":"Xu","year":"2019","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Cheng, W., Xu, W., Gu, X., Wang, S., Wang, Q., Ni, B., Lu, Z., Xiao, B., and Meng, X. (2023). A Comparative Study of VLF Transmitter Signal Measurements and Simulations during Two Solar Eclipse Events. Remote Sens., 15.","DOI":"10.3390\/rs15123025"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1016\/j.asr.2023.09.063","article-title":"Modeling of Solar Eclipse effects on the sub-ionospheric VLF\/LF signals observed by multiple stations over Japan","volume":"73","author":"Basak","year":"2024","journal-title":"Adv. Space Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1729","DOI":"10.1016\/S1364-6826(01)00048-7","article-title":"Solar flare induced ionospheric D-region enhancements from VLF amplitude observations","volume":"63","author":"Thomson","year":"2001","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10509-013-1699-4","article-title":"Solar flare induced D-region ionospheric perturbations evaluated from VLF measurements","volume":"350","author":"Singh","year":"2014","journal-title":"Astrophys. Space Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"6799","DOI":"10.1002\/2015JA022233","article-title":"Study of the solar flares effect on VLF radio signal propagating along NRK-ALG path using LWPC code","volume":"121","author":"Bouderba","year":"2016","journal-title":"J. Geophys. Res."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"7613","DOI":"10.1109\/TGRS.2019.2914920","article-title":"VLF measurements and modeling of the D-region response to the 2017 total solar eclipse","volume":"57","author":"Xu","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_11","first-page":"1508","article-title":"Response characteristics of very low frequency signals from JJI transmitter to solar flare events","volume":"64","author":"Gu","year":"2021","journal-title":"Chin. J. Geophys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"120","DOI":"10.3847\/1538-4357\/acea7f","article-title":"Observational Analysis of Ly\u03b1 Emission in Equivalent-magnitude Solar Flares","volume":"954","author":"Greatorex","year":"2023","journal-title":"Astrophys. J."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1459","DOI":"10.1029\/JZ065i005p01459","article-title":"VLF propagation effects of a D-region layer produced by cosmic rays","volume":"65","author":"Moler","year":"1960","journal-title":"J. Geophys. Res."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Kolarski, A., Veselinovi\u0107, N., Sre\u0107kovi\u0107, V., Miji\u0107, Z., Savi\u0107, M., and Dragi\u0107, A. (2023). Impacts of Extreme Space Weather Events on September 6, 2017 on Ionosphere and Primary Cosmic Rays. Remote Sens., 15.","DOI":"10.3390\/rs15051403"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"10230","DOI":"10.1029\/2019JA027044","article-title":"X-ray signatures of lightning-induced electron precipitation","volume":"124","author":"Marshall","year":"2019","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"e2021JD034914","DOI":"10.1029\/2021JD034914","article-title":"Chemical response of the upper atmosphere due to lightning-induced electron precipitation","volume":"126","author":"Xu","year":"2021","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e2022JA030964","DOI":"10.1029\/2022JA030964","article-title":"VLF and Ionospheric D-Region Perturbations Associated With WWLLN-Detected Lightning in the South Pacific Region","volume":"128","author":"Chand","year":"2023","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e2022JD036541","DOI":"10.1029\/2022JD036541","article-title":"Observations of Elves and Radio Wave Perturbations by Intense Lightning","volume":"128","author":"Tomicic","year":"2023","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1007\/s11430-021-9850-7","article-title":"Artificial modification of Earth\u2019s radiation belts by ground-based very-low-frequency (VLF) transmitters","volume":"65","author":"Ni","year":"2022","journal-title":"Sci. China Earth Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"e2023SW003827","DOI":"10.1029\/2023SW003827","article-title":"Long-Term Variations of Energetic Electrons Scattered by Signals From the North West Cape Transmitter","volume":"22","author":"Hu","year":"2024","journal-title":"Space Weather"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"e2023JA031930","DOI":"10.1029\/2023JA031930","article-title":"The Global Variation of Low Ionosphere Under Action of Energetic Electron Precipitation","volume":"128","author":"Chen","year":"2023","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Wait, J.R., and Spies, K.P. (1964). Characteristics of the Earth-Ionosphere Waveguide for VLF Radio Waves, NBS Tech.. Note 300.","DOI":"10.6028\/NBS.TN.300"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1781","DOI":"10.1029\/98RS02381","article-title":"Ionospheric D region remote sensing using vlf radio atmospherics","volume":"33","author":"Cummer","year":"1998","journal-title":"Radio Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"A10314","DOI":"10.1029\/2010JA015715","article-title":"Midlatitude daytime D region ionosphere variations measured from radio atmospherics","volume":"115","author":"Han","year":"2010","journal-title":"J. Geophys. Res."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"e2021JA029288","DOI":"10.1029\/2021JA029288","article-title":"An electron density model of the D-and E-region ionosphere for transionospheric VLF propagation","volume":"126","author":"Xu","year":"2021","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1745","DOI":"10.5194\/angeo-25-1745-2007","article-title":"Lightning-driven inner radiation belt energy deposition into the atmosphere: Implications for ionisation-levels and neutral chemistry","volume":"25","author":"Rodger","year":"2007","journal-title":"Ann. Geophys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"L08103","DOI":"10.1029\/2006GL029145","article-title":"Massive disturbance of the daytime lower ionosphere by the giant \u03b3-ray flare from magnetar SGR 1806-20","volume":"34","author":"Inan","year":"2007","journal-title":"Geophys. Res. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1731","DOI":"10.5194\/angeo-26-1731-2008","article-title":"Classification of X-ray solar flares regarding their effects on the lower ionosphere electron density profile","volume":"26","author":"Grubor","year":"2008","journal-title":"Ann. Geophys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"A07301","DOI":"10.1029\/2009JA015154","article-title":"Solar flare detection sensitivity using the South America VLF Network (SAVNET)","volume":"115","author":"Raulin","year":"2010","journal-title":"J. Geophys. Res."},{"key":"ref_30","first-page":"45","article-title":"A comparative study of measured amplitude and phase perturbations of VLF and LF radio signals induced by solar flares","volume":"188","year":"2014","journal-title":"Serb. Astron. J."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2194","DOI":"10.1002\/2014JA020689","article-title":"Long-term determination of energetic electron precipitation into the atmosphere from AARDDVARK subionospheric VLF observations","volume":"120","author":"Neal","year":"2015","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Mitra, A.P. (1974). Ionospheric Effects of Solar Flares, D. Reidel.","DOI":"10.1007\/978-94-010-2231-6"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"A11317","DOI":"10.1029\/2011JA016961","article-title":"Ionospheric response to the X-class solar flare on September 7 2005","volume":"116","author":"Xiong","year":"2011","journal-title":"J. Geophys. Res."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"e2019JA027431","DOI":"10.1029\/2019JA027431","article-title":"Responses of the thermosphere and ionosphere system to concurrent solar flares and geomagnetic storms","volume":"125","author":"Qian","year":"2020","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1016\/j.jastp.2007.01.012","article-title":"D-region electron density evaluated from VLF amplitude time delay during X-ray solar flares","volume":"69","author":"Grubor","year":"2007","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"e2022SW003249","DOI":"10.1029\/2022SW003249","article-title":"Measurements and Modeling of the Responses of VLF Transmitter Signals to X-Class Solar Flares at the Great Wall Station in Antarctica","volume":"21","author":"Xu","year":"2023","journal-title":"Space Weather"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Gu, X., Yi, J., Wang, S., Hu, Z., Xu, W., Ni, B., Li, B., He, F., Chen, X., and Hu, H. (2023). Comparison of VLF Signal Responses to Solar Flares along Daytime and Nighttime Propagation Paths. Remote Sens., 15.","DOI":"10.3390\/rs15041018"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.jastp.2003.09.009","article-title":"Solar flare induced ionospheric D-region enhancements from VLF phase and amplitude observations","volume":"66","author":"McRae","year":"2004","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"106074","DOI":"10.1016\/j.jastp.2023.106074","article-title":"Lower-ionosphere electron density and effective recombination coefficients from multi-instrument space observations and ground VLF measurements during solar flares","volume":"247","author":"Dominique","year":"2023","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1016\/j.jastp.2015.12.011","article-title":"Global Ionospheric Flare Detection System (GIFDS)","volume":"138\u2013139","author":"Wenzel","year":"2016","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1783","DOI":"10.1029\/2019SW002297","article-title":"Developing a Nowcasting Capability for X-Class Solar Flares Using VLF Radiowave Propagation Changes","volume":"17","author":"George","year":"2019","journal-title":"Space Weather"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"e2021SW002820","DOI":"10.1029\/2021SW002820","article-title":"Solar flare X-ray impacts on long subionospheric VLF paths","volume":"19","author":"Belcher","year":"2021","journal-title":"Space Weather"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"9841","DOI":"10.1002\/2017JA024647","article-title":"Pulsations in the Earth\u2019s lower ionosphere synchronized with solar flare emission","volume":"122","author":"Hayes","year":"2017","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1186\/s40623-018-0794-8","article-title":"Solar flare effects on D-region ionosphere using VLF measurements during low-and high-solar activity phases of solar cycle 24","volume":"70","author":"Kumar","year":"2018","journal-title":"Earth Planets Space"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1871","DOI":"10.1016\/j.asr.2016.01.023","article-title":"Development of ground-based elf\/vlf receiver system in wuhan and its first results","volume":"57","author":"Chen","year":"2016","journal-title":"Adv. Space Res."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1727","DOI":"10.1007\/s11431-021-2057-2","article-title":"Extraction of Alpha transmitter signals from single-station observations using the direction-finding method","volume":"65","author":"Gu","year":"2022","journal-title":"Sci. China Technol. Sci."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"e2020JA029101","DOI":"10.1029\/2020JA029101","article-title":"Statistical analysis of very low frequency atmospheric noise caused by the global lightning using ground-based observations in China","volume":"126","author":"Gu","year":"2021","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2000207","DOI":"10.1109\/TGRS.2021.3056092","article-title":"Responses of the very low frequency transmitter signals during the solar eclipse on December 26, 2019 over a North-South propagation path","volume":"60","author":"Gu","year":"2022","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"166","DOI":"10.1007\/s11431-016-6103-5","article-title":"First observations of low latitude whistlers using whu ELF\/VLF receiver system","volume":"60","author":"Chen","year":"2017","journal-title":"Sci. China Technol. Sci."},{"key":"ref_50","first-page":"4300","article-title":"Observations and analyses of the sunrise effect for NWC VLF transmitter signals","volume":"63","author":"Wang","year":"2020","journal-title":"Chin. J. Geophys."},{"key":"ref_51","first-page":"145","article-title":"Sunrise effect of very-low-frequency JJI transmitter signal propagating over an east-west path","volume":"65","author":"Wang","year":"2022","journal-title":"Chin. J. Geophys."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1109\/MCOM.1979.1089999","article-title":"Minimum shift keying: A spectrally efficient modulation","volume":"17","author":"Pasupathy","year":"1979","journal-title":"IEEE Commun. Mag."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"901","DOI":"10.1002\/2017JA024907","article-title":"Polarization of Narrowband VLF Transmitter Signals as an Ionospheric Diagnostic","volume":"123","author":"Gross","year":"2018","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"e2022JA030784","DOI":"10.1029\/2022JA030784","article-title":"First results of the wave measurements by the WHU VLF wave detection system at the Chinese Great Wall station in Antarctica","volume":"127","author":"Gu","year":"2022","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"1070","DOI":"10.1051\/0004-6361:20011694","article-title":"Temporal aspects and frequency distributions of solar soft X-ray flares","volume":"382","author":"Veronig","year":"2002","journal-title":"Astron. Astrophys."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1029\/2018RS006701","article-title":"Demonstrating the use of a class of min-max smoothers for D region event detection in narrow band VLF phase","volume":"54","author":"Lotz","year":"2019","journal-title":"Radio Sci."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/12\/2092\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:56:15Z","timestamp":1760108175000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/12\/2092"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,6,9]]},"references-count":56,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2024,6]]}},"alternative-id":["rs16122092"],"URL":"https:\/\/doi.org\/10.3390\/rs16122092","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,6,9]]}}}