{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,5]],"date-time":"2025-11-05T06:56:23Z","timestamp":1762325783785,"version":"build-2065373602"},"reference-count":41,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2023,12,12]],"date-time":"2023-12-12T00:00:00Z","timestamp":1702339200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NSFC-Shandong Joint Fund Key Project","award":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"],"award-info":[{"award-number":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"]}]},{"name":"Laoshan Laboratory science and technology innovation projects","award":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"],"award-info":[{"award-number":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"],"award-info":[{"award-number":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Strategic Priority Research Program of the Chinese Academy of Sciences","award":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"],"award-info":[{"award-number":["U22A20587","LSKJ202201406-2","41906027","XDB42000000"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Determining the dynamic processes of the subsurface ocean is a critical yet formidable undertaking given the sparse measurement resources available presently. In this study, using the light gradient boosting machine algorithm (LightGBM), we report for the first time a machine learning strategy for retrieving subsurface velocities at 1000 dbar depth in the Southern Ocean from information derived from satellite observations. Argo velocity measurements are used in the training and validation of the LightGBM model. The results show that reconstructed subsurface velocity agrees better with Argo velocity than reanalysis datasets. In particular, the subsurface velocity estimates have a correlation coefficient of 0.78 and an RMSE of 4.09 cm\/s, which is much better than the ECCO estimates, GODAS estimates, GLORYS12V1 estimates, and Ora-S5 estimates. The LightGBM model has a higher skill in the reconstruction of subsurface velocity than the random forest and the linear regressor models. The estimated subsurface velocity exhibits a statistically significant increase at 1000 dbar since the 1990s, providing new evidence for the deep acceleration of mean circulation in the Southern Ocean. This study demonstrates the great potential and advantages of statistical methods for subsurface velocity modeling and oceanic dynamical information retrieval.<\/jats:p>","DOI":"10.3390\/rs15245699","type":"journal-article","created":{"date-parts":[[2023,12,12]],"date-time":"2023-12-12T05:23:22Z","timestamp":1702358602000},"page":"5699","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Retrieval of Subsurface Velocities in the Southern Ocean from Satellite Observations"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-1617-4327","authenticated-orcid":false,"given":"Liang","family":"Xiang","sequence":"first","affiliation":[{"name":"Laboratory of Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China"},{"name":"Laboratory for Ocean and Climate Dynamics, Laoshan Laboratory, Qingdao 266237, China"},{"name":"Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China"}]},{"given":"Yongsheng","family":"Xu","sequence":"additional","affiliation":[{"name":"Laboratory of Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China"},{"name":"Laboratory for Ocean and Climate Dynamics, Laoshan Laboratory, Qingdao 266237, China"},{"name":"Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Hanwei","family":"Sun","sequence":"additional","affiliation":[{"name":"Spaceborne Radar Research Center, Beijing Institude of Radio Measurement, Beijing 100039, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5285-5738","authenticated-orcid":false,"given":"Qingjun","family":"Zhang","sequence":"additional","affiliation":[{"name":"Institute of Remote Sensing Satellite, Chinese Academy of Space Technology, Beijing 100094, China"}]},{"given":"Liqiang","family":"Zhang","sequence":"additional","affiliation":[{"name":"Institute of Remote Sensing Satellite, Chinese Academy of Space Technology, Beijing 100094, China"}]},{"given":"Lin","family":"Zhang","sequence":"additional","affiliation":[{"name":"Naval Submarine Academy, Qingdao 266199, China"}]},{"given":"Xiangguang","family":"Zhang","sequence":"additional","affiliation":[{"name":"Laboratory of Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China"},{"name":"Laboratory for Ocean and Climate Dynamics, Laoshan Laboratory, Qingdao 266237, China"},{"name":"Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China"}]},{"given":"Chao","family":"Huang","sequence":"additional","affiliation":[{"name":"Laboratory of Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China"},{"name":"Laboratory for Ocean and Climate Dynamics, Laoshan Laboratory, Qingdao 266237, China"},{"name":"Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4694-3683","authenticated-orcid":false,"given":"Dandan","family":"Zhao","sequence":"additional","affiliation":[{"name":"Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao 266061, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,12,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1038\/s41586-018-0320-y","article-title":"Global Surface Warming Enhanced by Weak Atlantic Overturning Circulation","volume":"559","author":"Chen","year":"2018","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"eabj8394","DOI":"10.1126\/sciadv.abj8394","article-title":"Surface Warming\u2013Induced Global Acceleration of Upper Ocean Currents","volume":"8","author":"Peng","year":"2022","journal-title":"Sci. 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