{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T08:27:37Z","timestamp":1772008057747,"version":"3.50.1"},"reference-count":46,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2024,8,2]],"date-time":"2024-08-02T00:00:00Z","timestamp":1722556800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2023YFC3107800"],"award-info":[{"award-number":["2023YFC3107800"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["42376011"],"award-info":[{"award-number":["42376011"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2023YFC3107800"],"award-info":[{"award-number":["2023YFC3107800"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42376011"],"award-info":[{"award-number":["42376011"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Sonic layer depth (SLD) is crucial in ocean acoustics research and profoundly influences sound propagation and Sonar detection. Carrying 90% of oceanic kinetic energy, mesoscale eddies significantly impact the propagation of acoustic energy in the ocean. Recent studies classified mesoscale eddies into normal eddies (warm anticyclonic and cold cyclonic eddies) and abnormal eddies (cold anticyclonic and warm cyclonic eddies). However, the influence of mesoscale eddies, especially abnormal eddies, on SLD remains unclear. Based on satellite altimeter and reanalysis data, we explored the influence of mesoscale eddies on seasonal variations in SLD in the South China Sea. We found that the vertical structures of temperature anomalies within the eddies had a significant impact on the sound speed field. A positive correlation between sonic layer depth anomaly (SLDA) and eddy intensity (absolute value of relative vorticity) was investigated. The SLDA showed significant seasonal variations: during summer (winter), the proportion of negative (positive) SLDA increased. Normal eddies (abnormal eddies) had a more pronounced effect during summer and autumn (spring and winter). Based on mixed-layer heat budget analysis, it was found that the seasonal variation in SLD was primarily induced by air\u2013sea heat fluxes. However, for abnormal eddies, the horizontal advection and vertical convective terms modulated the variations in the SLDA. This study provides additional theoretical support for mesoscale eddy\u2013acoustic coupling models and advances our understanding of the impact of mesoscale eddies on sound propagation.<\/jats:p>","DOI":"10.3390\/rs16152845","type":"journal-article","created":{"date-parts":[[2024,8,2]],"date-time":"2024-08-02T13:14:42Z","timestamp":1722604482000},"page":"2845","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Influence of Abnormal Eddies on Seasonal Variations in Sonic Layer Depth in the South China Sea"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-3864-8649","authenticated-orcid":false,"given":"Xintong","family":"Liu","sequence":"first","affiliation":[{"name":"School of Marine Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519020, China"}]},{"given":"Chunhua","family":"Qiu","sequence":"additional","affiliation":[{"name":"School of Marine Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519020, China"},{"name":"Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering School of Marine Sciences, Sun Yat-sen University, Guangzhou 510275, China"}]},{"given":"Tianlin","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Marine Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519020, China"},{"name":"Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering School of Marine Sciences, Sun Yat-sen University, Guangzhou 510275, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4957-4238","authenticated-orcid":false,"given":"Huabin","family":"Mao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Science and Technology on Operational Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China"}]},{"given":"Peng","family":"Xiao","sequence":"additional","affiliation":[{"name":"School of Ocean Engineering and Technology, Sun Yat-sen University, Zhuhai 519000, China"}]}],"member":"1968","published-online":{"date-parts":[[2024,8,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Jensen, F.B., Kuperman, W.A., Porter, M.B., and Schmidt, H. 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