Precipitable water vapour estimation using GPS in Uganda

Abstract

Additional thesis - Precipitation and especially rainfall are very important for the world’s population. It has its positive and negative side like providing water and contrary causing floods. Therefore it is of utmost importance to make clear and accurate weather predictions. The revolution of GPS in the last few decades gave a new opportunity in doing atmospheric science. Many researches have been focused on atmospheric science using GPS in Europe and North America. This research gives a better insight in the precipitable water vapour in the atmosphere above Uganda. Besides weather prediction the results of this report could be used for climate studies in Africa. Together with the research of A.M. Koning 2016 the accuracy of the to be determined zenith tropospheric delay and the precipitable water vapour in Uganda’s atmosphere was determined. This study was done during the months September and October of year 2016 in the surroundings of Kampala. To obtain the precipitable water vapour, 3 measurement rounds were done. All three networks were spanned by 3 dual frequency GPS receivers densified with at least 5 single frequency GPS receivers. The ionospheric delays measured with the dual frequency receivers were interpolated to the single frequency GPS receivers so these were transformed into dual frequency receivers as well. Thereafter, the RINEX files were uploaded on the PPP NRCan application where the zenith tropospheric delay was determined. Using the constant of proportionality found by Bevis 1994 together with Saastamoinen’s model to determine the zenith hydrostatic delay, the precipitable water vapour was found.