{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T06:11:13Z","timestamp":1782367873170,"version":"3.54.5"},"reference-count":40,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2023,10,15]],"date-time":"2023-10-15T00:00:00Z","timestamp":1697328000000},"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":"National Natural Science Foundation of China","award":["41804032"],"award-info":[{"award-number":["41804032"]}]},{"name":"National Natural Science Foundation of China","award":["SKLGIE2021-M-3-2"],"award-info":[{"award-number":["SKLGIE2021-M-3-2"]}]},{"name":"National Natural Science Foundation of China","award":["ZR2022QD078"],"award-info":[{"award-number":["ZR2022QD078"]}]},{"name":"Specialized Research Fund for State Key Laboratories","award":["42274040"],"award-info":[{"award-number":["42274040"]}]},{"name":"Specialized Research Fund for State Key Laboratories","award":["41804032"],"award-info":[{"award-number":["41804032"]}]},{"name":"Specialized Research Fund for State Key Laboratories","award":["SKLGIE2021-M-3-2"],"award-info":[{"award-number":["SKLGIE2021-M-3-2"]}]},{"name":"Specialized Research Fund for State Key Laboratories","award":["ZR2022QD078"],"award-info":[{"award-number":["ZR2022QD078"]}]},{"name":"State Key Laboratory of Geo-Information Engineering","award":["42274040"],"award-info":[{"award-number":["42274040"]}]},{"name":"State Key Laboratory of Geo-Information Engineering","award":["41804032"],"award-info":[{"award-number":["41804032"]}]},{"name":"State Key Laboratory of Geo-Information Engineering","award":["SKLGIE2021-M-3-2"],"award-info":[{"award-number":["SKLGIE2021-M-3-2"]}]},{"name":"State Key Laboratory of Geo-Information Engineering","award":["ZR2022QD078"],"award-info":[{"award-number":["ZR2022QD078"]}]},{"name":"Youth Project of Natural Science Foundation of Shandong Province","award":["42274040"],"award-info":[{"award-number":["42274040"]}]},{"name":"Youth Project of Natural Science Foundation of Shandong Province","award":["41804032"],"award-info":[{"award-number":["41804032"]}]},{"name":"Youth Project of Natural Science Foundation of Shandong Province","award":["SKLGIE2021-M-3-2"],"award-info":[{"award-number":["SKLGIE2021-M-3-2"]}]},{"name":"Youth Project of Natural Science Foundation of Shandong Province","award":["ZR2022QD078"],"award-info":[{"award-number":["ZR2022QD078"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Studying the temporal and spatial dependence of ionospheric anomalies using total electron content (TEC) can provide an important reference for developing empirical ionospheric models. In this study, winter anomaly, annual anomaly, and the contributions of winter anomaly to annual anomaly were investigated during solar cycle 24 (2008\u20132018) by using the global ionosphere maps of the Center for Orbit Determination in Europe during the geomagnetic activity quiet period (Kp \u2264 5) based on a regression approach. Our detailed analysis shows the following: (1) Winter anomaly is more significant at 11:00\u201313:00 local time (LT), and the region of winter anomaly extends from North America to the Far East with increasing solar activity levels. (2) The minimum level of solar activity corresponding to the occurrence of winter anomaly was calculated at each grid point, which can provide a reference for single-point ionospheric modeling. (3) The annual anomaly reaches its maximum at 12:00 LT when the TEC in December is 34.4% higher than in June. (4) At 12:00 LT, the winter anomaly contributes up to 32% to the annual anomaly (at this time, the winter hemisphere contributes 57% to the annual anomaly).<\/jats:p>","DOI":"10.3390\/rs15204968","type":"journal-article","created":{"date-parts":[[2023,10,15]],"date-time":"2023-10-15T10:47:32Z","timestamp":1697366852000},"page":"4968","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Analysis of Winter Anomaly and Annual Anomaly Based on Regression Approach"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-9055-0146","authenticated-orcid":false,"given":"Kaixin","family":"Wang","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"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0054-6690","authenticated-orcid":false,"given":"Jiandi","family":"Feng","sequence":"additional","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"},{"name":"State Key Laboratory of Geo-Information Engineering, Xi\u2019an 710054, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8861-5189","authenticated-orcid":false,"given":"Zhenzhen","family":"Zhao","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Geomatics, Shandong University of Technology, Zibo 255000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Baomin","family":"Han","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Geomatics, Shandong University of Technology, Zibo 255000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,15]]},"reference":[{"key":"ref_1","first-page":"685","article-title":"Some Further Measurements of Upper Atmospheric Ionization","volume":"150","author":"Appleton","year":"1935","journal-title":"Proc. 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