Contribution of permanent stations GPS data to estimate the water vapor content over Algeria
- 28 Downloads
In the last decade, important studies have demonstrated that GPS can be also used as an efficient tool for measuring the integrated water vapor (IWV) in the atmosphere which is a useful quantity for climatological and weather forecasting applications. This study presents the first results obtained by using the time series GPS stations of six local stations belonging to the continuously operating Algerian network, and 13 stations of the IGS (International GNSS Service) for the estimation of the value of the IWV locally. In this paper, tropospheric parameters are obtained from double difference processing of GPS observations, collected from 2008 to 2015, using the Bernese 5.2 software. For the validation of GPS IWV values, three approaches are used. In the first, the GPS IWV are compared with the corresponding ERA-Interim values derived from interpolations in time and space. The results show a good agreement with correlation coefficients exceeding 85% and an RMS (root mean square) between 2.22 and 5.53 kg m−2. In the second approach, we compare GPS IWV and radiosondes over two stations, where the results showed an acceptable concordance and equivalent to those of the first approach. In the third approach, the GPS ZWD (zenith wet delay), roughly IWV, values are compared with the daily rainfall data provided by the Algerian Meteorological Office. The results show that the temporal variation of ZWD and the high rainfall collected by rain gauges (not far from those of GPS) present a perfect coincidence over the surrounding observed peaks. Finally, the analysis of the annual time cycle of ZWD and precipitation carried out on the data of geographically and climatically different GPS stations shows that these two parameters depend on the latitude of the site. The first experimental results of this study further strengthen the strong potential of GPS in meteorological applications.
KeywordsGNSS/GPS Integrated water vapor ERA-Interim Precipitations
We are particularly grateful to our colleagues from geophysical and geodesic laboratories of Luxembourg University especially Addisu H. and Kibrom E. A. We thank the National Meteorological Office for allowing us to use their data. Thanks to the team of the National Institute of Cartography and Remote Sensing, which participated in the installation of the stations and observations campaigns.
- Baltink HK, Van Der Marel H, Van der Hoeven AG (2002) Integrated atmospheric water vapor estimates from a regional GPS network. J Geophys Res: Atmospheres 107(D3). https://doi.org/10.1029/2000JD000094
- Berrisford P, Dee DPKF, Fielding K, Fuentes M, Kallberg P, Kobayashi S, Uppala S (2009) The ERA-interim archive. ERA report series 1:1–16Google Scholar
- Bevis M, Businger S, Chiswell S, Herring TA, Anthes RA, Rocken C, Ware RH (1994) GPS meteorology: mapping zenith wet delays onto precipitable water. J Appl Meteorol 33(3):379–386. https://doi.org/10.1175/15200450(1994)033<0379:GMMZWD>2.0.CO;2 CrossRefGoogle Scholar
- Bock O, Bouin M, Walpersdorf A, Lafore JP, Janicot S, Guichard F, Agusti Panareda A (2007b) Comparison of ground based GPS precipitable water vapour to independent observations and NWP model reanalyzes over Africa. Q.J.R. Meteorol Soc 133:2011–2027. https://doi.org/10.1002/qj.185 CrossRefGoogle Scholar
- Boehm J, Werl B, Schuh H (2006) Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium-Range Weather Forecasts operational analysis data. J Geophys Res: Solid Earth 111(B2). https://doi.org/10.1029/2005JB003629
- Böhm J, Niell A, Tregoning P, Schuh H (2006) Global mapping function (GMF): a new empirical mapping function based on numerical weather model data. Geophys Res Lett 33(7) https://doi.org/10.1029/2005GL025546
- Dach R, Hugentobler U, Fridez P, Meindl M (2007) Bernese GPS software version 5.0. Astronomical institute, University of Bern, 640, 114Google Scholar
- Guerova G (2003) Application of GPS derived water vapor for numerical weather prediction in Switzerland. PhD thesis, Institute of Applied Physics, University of Bern, BerneGoogle Scholar
- Hagemann S, Bengtsson L, Gendt G (2003) On the determination of atmosphericwater vapor from GPS measurements. J Geophys Res: Atmospheres 108(D21). https://doi.org/10.1029/2002JD003235
- Jones J (2010) An assessment of the quality of GPS water vapor estimates and their usein operational meteorology and climate monitoring. PhD thesis, University of Nottingham. http://eprints.nottingham.ac.uk/11287/1/JJ_Thesis_Final.pdf
- Roeckner E, Bäuml G, Bonaventura L, Brokopf R, Esch M, Giorgetta M, Rhodn A (2003) The atmospheric general circulation model ECHAM 5. PART I: model description. Report/MPI für Meteorologie, 349. http://pubman.mpdl.mpg.de/pubman/item/escidoc:995269/component/escidoc:995268/max_scir p_349.pdf
- Vey S, Dietrich R., Fritsche M, Rulke A, Steigenberger P, Rothacher M (2009) On the homogeneity and interpretation of precipitale water time series derived from global GPS observations. J Geophys Res (D: Atmos), 114, https://doi.org/10.1029/2008JD010415.