{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T23:59:48Z","timestamp":1768262388354,"version":"3.49.0"},"reference-count":38,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2018,6,12]],"date-time":"2018-06-12T00:00:00Z","timestamp":1528761600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Research Grant for Specially Hired Associate Professor of Central South University","award":["202045005"],"award-info":[{"award-number":["202045005"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The tropospheric wet delay induced by water vapor is a major error source in precise point positioning (PPP), significantly influencing the convergence time to obtain high-accuracy positioning. Thus, high-quality water vapor information is necessary to support PPP processing. This study presents the use of tomographic wet refractivity (WR) fields in PPP to examine their impacts on the positioning performance. Tests are carried out based on 1-year of 2013 global navigation satellite system (GNSS) observations (30 s sampling rate) from three stations with different altitudes in the Hong Kong GNSS network. Coordinate errors with respect to reference values at a 0.1 m level of convergence is used for the north, east, and up components, whilst an error of 0.2 m is adopted for 3D position convergence. Experimental results demonstrate that, in both static and kinematic modes, the tomography-based PPP approach outperforms empirical tropospheric models in terms of positioning accuracy and convergence time. Compared with the results based on traditional, Saastamoinen, AN (Askne and Nordis), and VMF1 (Vienna Mapping Function 1) models, 23\u201348% improvements of positioning accuracy, and 5\u201330% reductions of convergence time are achieved with the application of tomographic WR fields. When using a tomography model, about 35% of the solutions converged within 20 min, whereas only 23%, 25%, 25%, and 30% solutions converged within 20 min for the traditional, Saastamoinen, AN, and VMF1 models, respectively. Our study demonstrates the benefit to real-time PPP processing brought by additional tomographic WR fields as they can significantly improve the PPP solution and reduce the convergence time for the up component.<\/jats:p>","DOI":"10.3390\/rs10060928","type":"journal-article","created":{"date-parts":[[2018,6,12]],"date-time":"2018-06-12T10:58:32Z","timestamp":1528801112000},"page":"928","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Real-Time Precise Point Positioning Using Tomographic Wet Refractivity Fields"],"prefix":"10.3390","volume":"10","author":[{"given":"Wenkun","family":"Yu","sequence":"first","affiliation":[{"name":"Department of Land Surveying & Geo-Informatics, Hong Kong Polytechnic University, Hong Kong, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Biyan","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Geosciences and Info-Physics, Central South University, Changsha 410000, China"},{"name":"Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring Ministry of Education, School of Geoscience and Info-Physics, Central South University, Changsha 410000, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wujiao","family":"Dai","sequence":"additional","affiliation":[{"name":"School of Geosciences and Info-Physics, Central South University, Changsha 410000, China"},{"name":"Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring Ministry of Education, School of Geoscience and Info-Physics, Central South University, Changsha 410000, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaomin","family":"Luo","sequence":"additional","affiliation":[{"name":"GNSS Research Center, Wuhan University, Wuhan 430000, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,6,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5005","DOI":"10.1029\/96JB03860","article-title":"Precise point positioning for the efficient and robust analysis of GPS data from large networks","volume":"102","author":"Zumberge","year":"1997","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1007\/s11200-005-0022-4","article-title":"A possible detection of the 26 December 2004 Great Sumatra-Andaman Islands Earthquake with solution products of the International GNSS Service","volume":"49","author":"Kouba","year":"2005","journal-title":"Stud. Geophys. Geod."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1007\/s00190-010-0424-0","article-title":"Regional reference network augmented precise point positioning for instantaneous ambiguity resolution","volume":"85","author":"Li","year":"2011","journal-title":"J. Geodesy"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"10044","DOI":"10.1002\/2014JD021486","article-title":"Real-time retrieval of precipitable water vapor from GPS precise point positioning","volume":"119","author":"Yuan","year":"2014","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Leick, A., Rapoport, L., and Tatarnikov, D. (2015). GPS Satellite Surveying, Wiley. [4th ed.].","DOI":"10.1002\/9781119018612"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Luo, X., Lou, Y., Xiao, Q., Gu, S., Chen, B., and Liu, Z. (2018). Investigation of ionospheric scintillation effects on BDS precise point positioning at low-latitude regions. GPS Solut., 22.","DOI":"10.1007\/s10291-018-0728-8"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"055003","DOI":"10.1088\/0957-0233\/24\/5\/055003","article-title":"Near-real-time regional troposphere models for the GNSS precise point positioning technique","volume":"24","author":"Hadas","year":"2013","journal-title":"Meas. Sci. Technol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Lou, Y., Huang, J., Zhang, W., Liang, H., Zheng, F., and Liu, J. (2017). A New Zenith Tropospheric Delay Grid Product for Real-Time PPP Applications over China. Sensors, 18.","DOI":"10.3390\/s18010065"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Wilgan, K., Hadas, T., Hordyniec, P., and Bosy, J. (2017). Real-time precise point positioning augmented with high-resolution numerical weather prediction model. GPS Solut.","DOI":"10.1007\/s10291-017-0617-6"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"433","DOI":"10.1007\/s10291-014-0403-7","article-title":"Development of an improved empirical model for slant delays in the troposphere (GPT2w)","volume":"19","author":"Schindelegger","year":"2015","journal-title":"GPS Solut."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"663","DOI":"10.1109\/TGRS.2015.2456099","article-title":"A Comprehensive Evaluation and Analysis of the Performance of Multiple Tropospheric Models in China Region","volume":"54","author":"Chen","year":"2016","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1186\/1880-5981-66-30","article-title":"Local troposphere augmentation for real-time precise point positioning","volume":"66","author":"Shi","year":"2014","journal-title":"Earth Planets Space"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"899","DOI":"10.1017\/S0373463314000265","article-title":"A New Method to Accelerate PPP Convergence Time by using a Global Zenith Troposphere Delay Estimate Model","volume":"67","author":"Yao","year":"2014","journal-title":"J. Navig."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"677","DOI":"10.1007\/s10291-015-0477-x","article-title":"Using a regional numerical weather prediction model for GNSS positioning over Brazil","volume":"20","author":"Alves","year":"2016","journal-title":"GPS Solut."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1007\/s10291-016-0518-0","article-title":"Modeling tropospheric wet delays with dense and sparse network configurations for PPP-RTK","volume":"21","author":"Morel","year":"2017","journal-title":"GPS Solut."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"115107","DOI":"10.1088\/0957-0233\/22\/11\/115107","article-title":"Performance analysis of NOAA tropospheric signal delay model","volume":"22","author":"Ibrahim","year":"2011","journal-title":"Meas. Sci. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"5965","DOI":"10.5194\/amt-9-5965-2016","article-title":"Tropospheric delay parameters from numerical weather models for multi-GNSS precise positioning","volume":"9","author":"Lu","year":"2016","journal-title":"Atmos. Meas. Tech."},{"key":"ref_18","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_19","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. Geodesy"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.atmosres.2011.12.008","article-title":"The precision of humidity in GNSS tomography","volume":"107","author":"Rohm","year":"2012","journal-title":"Atmos. Res."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5249","DOI":"10.5194\/amt-9-5249-2016","article-title":"Assessing the performance of troposphere tomographic modeling using multi-source water vapor data during Hong Kong\u2019s rainy season from May to October 2013","volume":"9","author":"Chen","year":"2016","journal-title":"Atmos. Meas. Tech."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1002\/qj.785","article-title":"On the relationship between water vapour field evolution and the life cycle of precipitation systems","volume":"137","author":"Reverdy","year":"2011","journal-title":"Q. J. R. Meteorol. Soc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1127\/0941-2948\/2013\/0413","article-title":"Precipitation on the lee side of the Vosges Mountains: Multi-instrumental study of one case from the COPS campaign","volume":"22","author":"Labbouz","year":"2013","journal-title":"Meteorol. Z."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1839","DOI":"10.1109\/JSTARS.2015.2406313","article-title":"Capturing the signature of severe weather events in Australia using GPS measurements","volume":"8","author":"Zhang","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.1175\/JTECH-D-16-0115.1","article-title":"Detecting Water Vapor Variability during Heavy Precipitation Events in Hong Kong Using the GPS Tomographic Technique","volume":"34","author":"Chen","year":"2017","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Saastamoinen, J. (1972). Atmospheric correction for the troposphere and stratosphere in radio ranging satellites. The Use of Artificial Satellites for Geodesy, AGU.","DOI":"10.1029\/GM015p0247"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/BF02522083","article-title":"Contributions to the theory of atmospheric refraction Part II, Refraction corrections in satellite geodesy","volume":"107","author":"Saastamoinen","year":"1973","journal-title":"Bull. Geodesique"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1029\/RS022i003p00379","article-title":"Estimation of tropospheric delay for microwaves from surface weather data","volume":"22","author":"Askne","year":"1987","journal-title":"Radio Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1007\/s00190-008-0216-y","article-title":"Forecast Vienna Mapping Functions 1 for real-time analysis of space geodetic observations","volume":"83","author":"Boehm","year":"2008","journal-title":"J. Geodesy"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"4861","DOI":"10.5194\/amt-9-4861-2016","article-title":"Comparison of GPS tropospheric delays derived from two consecutive EPN reprocessing campaigns from the point of view of climate monitoring","volume":"9","author":"Baldysz","year":"2016","journal-title":"Atmos. Meas. Tech."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1475","DOI":"10.5194\/amt-7-1475-2014","article-title":"Limited constraint, robust Kalman filtering for GNSS troposphere tomography","volume":"7","author":"Rohm","year":"2014","journal-title":"Atmos. Meas. Tech."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2661","DOI":"10.1029\/2000GL011525","article-title":"Obtaining single path phase delays from GPS double differences","volume":"27","author":"Alber","year":"2000","journal-title":"Geophys. Res. Lett."},{"key":"ref_33","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_34","unstructured":"Kouba, J., and Street, B. (2018, June 12). A Guide to Using International GNSS Service (IGS) Products. Available online: https:\/\/kb.igs.org\/hc\/en-us\/articles\/201271873-A-Guide-to-Using-the-IGS-Products."},{"key":"ref_35","unstructured":"Dach, R., Lutz, S., Walser, P., and Fridez, P. (2015). Bernese GNSS Software Version 5.2, Astronomical Institute, University of Bern. User Manual."},{"key":"ref_36","unstructured":"Chan, K., and Li, C. (2018, June 12). The Hong Kong Satellite Positioning Reference Station Network (SatRef)\u2014System Configurations, Applications and Services 2007. Available online: https:\/\/www.fig.net\/resources\/proceedings\/fig_proceedings\/fig2007\/papers\/ts_5a\/ts05a_04_chan_li_1332.pdf."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1007\/s10291-013-0345-5","article-title":"Integrating GPS and GLONASS to accelerate convergence and initialization times of precise point positioning","volume":"18","author":"Li","year":"2014","journal-title":"GPS Solut."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1002\/qj.828","article-title":"The ERA-Interim reanalysis: Configuration and performance of the data assimilation system","volume":"137","author":"Dee","year":"2011","journal-title":"Q. J. R. Meteorol. Soc."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/6\/928\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:08:23Z","timestamp":1760195303000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/6\/928"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,6,12]]},"references-count":38,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2018,6]]}},"alternative-id":["rs10060928"],"URL":"https:\/\/doi.org\/10.3390\/rs10060928","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,6,12]]}}}