{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T10:27:26Z","timestamp":1768818446757,"version":"3.49.0"},"reference-count":65,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2022,11,9]],"date-time":"2022-11-09T00:00:00Z","timestamp":1667952000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Natural Science Foundation of China","award":["42274021"],"award-info":[{"award-number":["42274021"]}]},{"name":"Natural Science Foundation of China","award":["B20046"],"award-info":[{"award-number":["B20046"]}]},{"name":"Natural Science Foundation of China","award":["2022ZZCX06"],"award-info":[{"award-number":["2022ZZCX06"]}]},{"name":"Natural Science Foundation of China","award":["41730109"],"award-info":[{"award-number":["41730109"]}]},{"name":"Construction Program of Space-Air-Ground-Well Cooperative Awareness Spatial Information Project","award":["42274021"],"award-info":[{"award-number":["42274021"]}]},{"name":"Construction Program of Space-Air-Ground-Well Cooperative Awareness Spatial Information Project","award":["B20046"],"award-info":[{"award-number":["B20046"]}]},{"name":"Construction Program of Space-Air-Ground-Well Cooperative Awareness Spatial Information Project","award":["2022ZZCX06"],"award-info":[{"award-number":["2022ZZCX06"]}]},{"name":"Construction Program of Space-Air-Ground-Well Cooperative Awareness Spatial Information Project","award":["41730109"],"award-info":[{"award-number":["41730109"]}]},{"name":"Independent Innovation Project of \u201cDoubleFirst Class\u201d Construction","award":["42274021"],"award-info":[{"award-number":["42274021"]}]},{"name":"Independent Innovation Project of \u201cDoubleFirst Class\u201d Construction","award":["B20046"],"award-info":[{"award-number":["B20046"]}]},{"name":"Independent Innovation Project of \u201cDoubleFirst Class\u201d Construction","award":["2022ZZCX06"],"award-info":[{"award-number":["2022ZZCX06"]}]},{"name":"Independent Innovation Project of \u201cDoubleFirst Class\u201d Construction","award":["41730109"],"award-info":[{"award-number":["41730109"]}]},{"name":"the State Key Program of the National Natural Science Foundation of China","award":["42274021"],"award-info":[{"award-number":["42274021"]}]},{"name":"the State Key Program of the National Natural Science Foundation of China","award":["B20046"],"award-info":[{"award-number":["B20046"]}]},{"name":"the State Key Program of the National Natural Science Foundation of China","award":["2022ZZCX06"],"award-info":[{"award-number":["2022ZZCX06"]}]},{"name":"the State Key Program of the National Natural Science Foundation of China","award":["41730109"],"award-info":[{"award-number":["41730109"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>One of the main challenges of Global Navigation Satellite System (GNSS) tomography is in solving ill-conditioned system equations. Vertical constraint models are typically used in the solution procedure and play an important role in the quality of the GNSS tomography, in addition to helping resolve ill-posed problems in system equations. In this study, based on a water vapor (WV) parameter, namely IRPWV, a new vertical constraint model with six sets of coefficients for six different WV states was developed and tested throughout 2019 in the Hong Kong region with four tomographic schemes, which were carried out with the model and the traditional vertical constraint model using three different types of water vapor scale height parameters. Experimental results were numerically compared against their corresponding radiosonde-derived WV values. Compared with the tests that used the traditional model, our results showed that, first, for the daily relative error of WV density (WVD) less than 30%, the new model can lead to at least 10% and 49% improvement on average at the lower layers (below 3 km, except for the ground surface) and the upper layers (about 5\u201310 km), respectively. Second, the skill score of the monthly root-mean-square error (RMSE) of layered WVD above 10 accounted for about 83%, 87%, and 64%. Third, for the annual biases of layered WVD, the new model significantly decreased by 1.1\u20131.5 g\/m3 at layers 2\u20133 (about 1 km), where all schemes showed the maximal bias value. Finally, for the annual RMSE of layered WVD, the new model at the lower (about 0.6\u20133 km) and upper layers improved by 13\u201342% and 5\u201347%, respectively. Overall, the new model performed better on GNSS tomography and significantly improved the accuracy of GNSS tomographic results, compared to the traditional model.<\/jats:p>","DOI":"10.3390\/rs14225656","type":"journal-article","created":{"date-parts":[[2022,11,10]],"date-time":"2022-11-10T02:07:48Z","timestamp":1668046068000},"page":"5656","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Development of a New Vertical Water Vapor Model for GNSS Water Vapor Tomography"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5380-0587","authenticated-orcid":false,"given":"Moufeng","family":"Wan","sequence":"first","affiliation":[{"name":"Jiangsu Key Laboratory of Resources and Environmental Information Engineering, China University of Mining and Technology, Xuzhou 221116, China"},{"name":"School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9376-1148","authenticated-orcid":false,"given":"Kefei","family":"Zhang","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Resources and Environmental Information Engineering, China University of Mining and Technology, Xuzhou 221116, China"},{"name":"School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0994-402X","authenticated-orcid":false,"given":"Suqin","family":"Wu","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Resources and Environmental Information Engineering, China University of Mining and Technology, Xuzhou 221116, China"},{"name":"School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0607-6877","authenticated-orcid":false,"given":"Peng","family":"Sun","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Resources and Environmental Information Engineering, China University of Mining and Technology, Xuzhou 221116, China"},{"name":"School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China"}]},{"given":"Longjiang","family":"Li","sequence":"additional","affiliation":[{"name":"Jiangsu Key Laboratory of Resources and Environmental Information Engineering, China University of Mining and Technology, Xuzhou 221116, China"},{"name":"School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"373","DOI":"10.1038\/359373a0","article-title":"The Hydrological Cycle and Its Influence on Climate","volume":"359","author":"Chahine","year":"1992","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5686","DOI":"10.1175\/JCLI3990.1","article-title":"Robust Responses of the Hydrological Cycle to Global Warming","volume":"19","author":"Held","year":"2006","journal-title":"J. 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