{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:21:49Z","timestamp":1760235709195,"version":"build-2065373602"},"reference-count":37,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2021,9,24]],"date-time":"2021-09-24T00:00:00Z","timestamp":1632441600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["41904013","41774026","41730109"],"award-info":[{"award-number":["41904013","41774026","41730109"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"National Science Foundation of Jiangsu Normal University","award":["19XSRS010"],"award-info":[{"award-number":["19XSRS010"]}]},{"name":"Postgraduate Research &amp; Practice Innovation Program of Jiangsu Province","award":["KYCX20_2363"],"award-info":[{"award-number":["KYCX20_2363"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Global Navigation Satellite System (GNSS) water vapor tomography provides a four-dimensional (4-D) distribution of water vapor in the atmosphere for weather monitoring. It has developed into a widely used technique in numerical weather prediction (NWP). Vertical stratification is essential in discretizing the tomographic region. Traditional discretization methods divide the tomographic area into regular voxels with an equal height interval, which ignores the dynamic exponential distribution of water vapor. In recent years, non-uniform stratification methods have been widely validated by tomographic experiments. However, such experiments have not proposed a specific calculation method for stratification thickness. Therefore, in this paper, we introduced an adaptive non-uniform stratification method that follows the exponential distribution of water vapor in the tomographic region and presented the process of iterative calculation to acquire the optimal stratification interval. The proposed approach was applied based on the exponential decreasing trend in water vapor with increasing altitude. Moreover, it could adaptively calculate the interval of stratification height according to water vapor content. The tomographic experiments were performed using Global Positioning System (GPS) data from 19 ground-based stations in the Hong Kong Satellite Positioning Reference Station Network (SatRef) from 1 to 31 August 2019. The results indicated that, compared to the traditional stratification method, the root mean square error derived from the proposed approach was reduced by 0.26 g\/m3. Additionally, severe weather can negatively affect the accuracy of the tomographic results. The results also showed that the accuracy of the tomographic results was reduced with increasing altitude. Moreover, the performance of the tomographic water vapor fields below 3000 m was improved by the proposed approach.<\/jats:p>","DOI":"10.3390\/rs13193818","type":"journal-article","created":{"date-parts":[[2021,9,27]],"date-time":"2021-09-27T22:16:38Z","timestamp":1632780998000},"page":"3818","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["An Adaptive Non-Uniform Vertical Stratification Method for Troposphere Water Vapor Tomography"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4621-566X","authenticated-orcid":false,"given":"Hao","family":"Wang","sequence":"first","affiliation":[{"name":"School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou 221116, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8603-8322","authenticated-orcid":false,"given":"Nan","family":"Ding","sequence":"additional","affiliation":[{"name":"School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou 221116, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1243-0481","authenticated-orcid":false,"given":"Wenyuan","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"15787","DOI":"10.1029\/92JD01517","article-title":"GPS meteorology: Remote sensing of atmospheric water vapor using the Global Positioning System","volume":"97","author":"Bevis","year":"1992","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.1016\/S1364-6826(00)00249-2","article-title":"Ground-based GPS water vapour estimation: Potential for meteorological forecasting","volume":"63","author":"Baker","year":"2001","journal-title":"J. Atmos. Solar-Terr. Phys."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/S0079-1946(97)00254-1","article-title":"An experiment for estimation of the spatial and temporal variations of water vapor using GPS data","volume":"23","author":"Ruis","year":"1998","journal-title":"Phys. Chem. Earth"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1175\/1520-0426(1995)012<0468:GSOAWV>2.0.CO;2","article-title":"GPS\/STORM-GPS sensing of atmospheric water vapor for meteorology","volume":"12","author":"Rocken","year":"1995","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"830","DOI":"10.1175\/1520-0450(1996)035<0830:GMDEOT>2.0.CO;2","article-title":"GPS Meteorology: Direct estimation of the absolute value of precipitable water","volume":"35","author":"Duan","year":"1996","journal-title":"J. Appl. Meteorol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1175\/JTECH-1697.1","article-title":"Comparison of near-real time estimates of integrated water vapor derived with GPS, radiosondes, and microwave radiometer","volume":"22","author":"Baelen","year":"2005","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1807","DOI":"10.1029\/97JD03015","article-title":"Three months of continuous monitoring of atmospheric water vapor with a network of Global Positioning System receivers","volume":"103","author":"Emardson","year":"1998","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1918","DOI":"10.1109\/TGRS.2008.2010401","article-title":"Variability and climatology of PWV from global 13-year GPS observations","volume":"47","author":"Jin","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"53","DOI":"10.3319\/TAO.2000.11.1.53(COSMIC)","article-title":"The GPS radio occultation technique","volume":"11","author":"Kursinski","year":"2001","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1007\/s00585-000-0223-7","article-title":"4D tropospheric tomography using GPS slant wet delays","volume":"18","author":"Flores","year":"2000","journal-title":"Ann. Geophys."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"935","DOI":"10.1186\/BF03352308","article-title":"Local GPS tropospheric tomography","volume":"52","author":"Hirahara","year":"2000","journal-title":"Earth Planets Space"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"927","DOI":"10.1186\/BF03352307","article-title":"Three-dimensional distribution of water vapor estimated from tropospheric delay of GPS data in a mesoscale precipitation system of the Baiu front","volume":"52","author":"Seko","year":"2000","journal-title":"Earth Planets Space"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2211","DOI":"10.1016\/j.asr.2005.07.002","article-title":"Tomographic determination of the spatial distribution of water vapor using GPS observations","volume":"37","author":"Troller","year":"2006","journal-title":"Adv. Space Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1704","DOI":"10.1016\/j.asr.2010.05.034","article-title":"Development of a GNSS water vapour tomography system using algebraic reconstruction techniques","volume":"47","author":"Bender","year":"2011","journal-title":"Adv. Space Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1007\/s00190-014-0715-y","article-title":"Voxel-optimized regional water vapor tomography and comparison with radiosonde and numerical weather model","volume":"88","author":"Chen","year":"2014","journal-title":"J. Geodesy"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"7185","DOI":"10.1109\/TGRS.2016.2597241","article-title":"Maximally using GPS observation for water vapor tomography","volume":"54","author":"Yao","year":"2016","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Bao, Z., Fan, Q., Yao, Y., Xu, C., and Li, X. (2017). An improved tomography approach based on adaptive smoothing and ground meteorological observations. Remote Sens., 9.","DOI":"10.3390\/rs9090886"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"5880","DOI":"10.1109\/JSTARS.2016.2546316","article-title":"An optimal weighting method of global positioning system (GPS) troposphere tomography","volume":"9","author":"Guo","year":"2017","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1805","DOI":"10.5194\/angeo-31-1805-2013","article-title":"GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles","volume":"31","author":"Xia","year":"2013","journal-title":"Ann. Geophys."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Zhao, Q., Yao, Y., and Yao, W. (2018). Troposphere water vapour tomography: A horizontal parameterised approach. Remote Sens., 10.","DOI":"10.3390\/rs10081241"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"311","DOI":"10.5194\/angeo-35-311-2017","article-title":"New parameterized model for GPS water vapor tomography","volume":"35","author":"Ding","year":"2017","journal-title":"Ann. Geophys."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"911","DOI":"10.5194\/angeo-32-911-2014","article-title":"Near real-time water vapor tomography using ground-based GPS and meteorological data: Long-term experiment in Hong Kong","volume":"32","author":"Jiang","year":"2014","journal-title":"Ann. Geophys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1007\/s00190-011-0454-2","article-title":"4D GPS water vapor tomography: New parameterized approaches","volume":"85","author":"Perler","year":"2011","journal-title":"J. Geod."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1007\/BF02826630","article-title":"Determination of weighed mean tropospheric temperature using ground meteorological measurements","volume":"4","author":"Liu","year":"2001","journal-title":"Geo-Spat. Inf. Sci."},{"key":"ref_25","first-page":"1","article-title":"Global Mapping Function (GMF): A new empirical mapping function based on numerical weather model data","volume":"33","author":"Niell","year":"2006","journal-title":"Geophys. Res. Lett."},{"key":"ref_26","first-page":"247","article-title":"Atmospheric correction for the troposphere and the stratosphere in radio ranging satellites","volume":"15","author":"Saastamoinen","year":"1972","journal-title":"Use Artif. Satell. Geod."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"230","DOI":"10.5081\/jgps.4.1.230","article-title":"Troposphere modeling in a regional GPS network","volume":"4","author":"Skone","year":"2005","journal-title":"J. Glob. Position. Syst."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2927","DOI":"10.1109\/TGRS.2006.877755","article-title":"Water vapor tomography using GPS phase observations: Simulation results","volume":"44","author":"Nilsson","year":"2006","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1727","DOI":"10.5194\/angeo-25-1727-2007","article-title":"Preconditions to ground based GPS water vapour tomography","volume":"25","author":"Bender","year":"2007","journal-title":"Ann. Geophys."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"775","DOI":"10.6028\/jres.080A.071","article-title":"Vapor pressure formulation for water in range 0 to 100\u00b0. A Revision","volume":"80A","author":"Wexler","year":"1976","journal-title":"J. Res. Natl. Bur. Stand. Sect. A Phys. Chem."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1855","DOI":"10.1175\/JAMC-D-11-0119.1","article-title":"Analysis of water vapor over Nigeria using radiosonde and satellite data","volume":"51","author":"Adeyemi","year":"2012","journal-title":"Appl. Meteorol. Clim."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1002\/joc.3412","article-title":"A multi-sensor study of water vapour from radiosonde, MODIS and AERONET: A case study of Hong Kong","volume":"33","author":"Liu","year":"2013","journal-title":"Int. J. Climatol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1007\/s13143-010-1012-1","article-title":"Comparison of atmospheric water vapor profiles obtained by GPS, MWR, and radiosonde","volume":"46","author":"Ha","year":"2010","journal-title":"Asia-Pac. J. Atmos. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1475","DOI":"10.1109\/LGRS.2018.2853183","article-title":"Hybrid regularized GPS tropospheric sensing using 3-D ray tracing technique","volume":"15","author":"Amerian","year":"2018","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_35","first-page":"193","article-title":"B-spline function-based approach for GPS tropospheric tomography","volume":"24","author":"Amerian","year":"2020","journal-title":"GPS Solut."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1007\/s10291-021-01114-1","article-title":"A new integrated method of GNSS and MODIS measurements for tropospheric water vapor tomography","volume":"25","author":"Zhang","year":"2021","journal-title":"GPS Solut."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Zhang, W., Zhang, S., Ding, N., and Zhao, Q. (2020). A tropospheric tomography method with a novel height factor model including two parts: Isotropic and anisotropic height factors. Remote Sens., 12.","DOI":"10.3390\/rs12111848"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/19\/3818\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:04:12Z","timestamp":1760166252000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/19\/3818"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,24]]},"references-count":37,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2021,10]]}},"alternative-id":["rs13193818"],"URL":"https:\/\/doi.org\/10.3390\/rs13193818","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2021,9,24]]}}}