Precipitable water comparisons over ghana using PPP techniques and reanalysis data

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dc.date.accessioned2019-12-09T15:26:37Z
dc.date.accessioned2023-04-19T01:30:22Z
dc.date.available2019-12-09T15:26:37Z
dc.date.available2023-04-19T01:30:22Z
dc.date.issued2017-10
dc.descriptionAn article published by South African Journal of Geomatics, Vol. 6. No. 3, October 2017 and available at DOI: http://dx.doi.org/10.4314/sajg.v6i3.13en_US
dc.description.abstractAtmospheric Water vapor is an important greenhouse gas and contributes greatly in maintaining the Earth’s energy balance. This critical meteorological parameter is not being sensed by any of the 22 synoptic weather stations in Ghana. This study presents a highly precise tool for water vapor sensing based on the concept Global Navigation Satellite Systems (GNSS) meteorology and tests the computed results against global reanalysis data. Conventional approaches used to sense the atmospheric water vapor or Precipitable Water (PW) such as radiosondes, hygrometers, microwave radiometers or sun photometers are expensive and have coverage and temporal limitations. Whereas GNSS meteorological concept offers an easier, inexpensive and all-weather technique to retrieve PW or Integrated Water Vapor (IWV) from zenith tropospheric delays (ZTD) over a reference station. This study employed precise point positioning (PPP) techniques to quantify the extend of delays on the signal due to the troposphere and stratosphere where atmospheric water vapor resides. Stringent processing criteria were set using an elevation cut-off of 5 degrees, precise orbital and clock products were used as well as nominal tropospheric corrections and mapping functions implemented. The delays which are originally slanted are mapped unto the zenith direction and integrated with surface meteorological parameters to retrieve PW or IWV. The gLAB software, Canadian Spatial Reference System (CSRS) and Automatic Precise Positioning Service (APPS) online PPP services were the approaches used to compute ZTD. PW values obtained were compared with Japanese Metro Agency Reanalysis (JRA), European Centre for Medium-Range Weather Forecasts Reanalysis (ERA-interim) and National Center for Environmental Prediction (NCEP) global reanalysis data. Correlation analysis were run on the logged station data using the three approaches and global reanalysis data. The obtained results show stronger correlation between the retrieved PW values and those provided by the ERA-interim. Finally, the study results indicate that with a more densified network of GNSS base stations the retrieved PW or IWV will greatly improve numerical weather predictions in Ghana.en_US
dc.identifier.citationSouth African Journal of Geomatics, Vol. 6. No. 3, October 2017en_US
dc.identifier.urihttps://ir.knust.edu.gh/handle/123456789/11823
dc.language.isoenen_US
dc.publisherSouth African Journal of Geomaticsen_US
dc.subjectGNSS Signalsen_US
dc.subjectPPPen_US
dc.subjectIntegrated Water vapouren_US
dc.subjectPrecipitable Wateren_US
dc.subjectReanalysis Modelsen_US
dc.titlePrecipitable water comparisons over ghana using PPP techniques and reanalysis dataen_US
dc.typeArticleen_US
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