Precipitable water vapour estimation using GPS in Uganda

Precipitable water vapour estimation using GPS in Uganda: A study on obtaining the Zenith Wet Delay

Koning, A.M.

van de Giesen, N.C. (mentor)
Verhagen, A.A. (mentor)
D'ujanga, F. (mentor)

Civil Engineering and Geosciences

Geoscience and Remote Sensing

2017-01-31

Additional thesis - To improve weather monitoring, local near-real time weather forecasts and climate monitoring, a dense network of sensors should be set up. As shown already in the 1990s, GPS is a promising measurement device to form a dense network for meteorology observation. Because of economic reasons, a network of dual frequency GPS receivers is densified using low-cost single frequency GPS receivers. In this thesis and the complementary thesis written by E.M.J. Stierman (2016), respectively, the quality of the Tropospheric Zenith delay and the Precipiatble Water Vapour recordings that are estimated using the single frequency receivers in the network are investigated. To do this, two networks of small (<10km) spacing and large (30-90 km) spacing have been set-up. After this, a L2- and C2-measurement is generated for the single frequency receivers, using epoch-differenced ionospheric delay for L2 and regular ionospheric delay for the C2 measurement together with the L1 and C1 observations of the single frequencyreceiver. This is done to be able to use web-based PPP processing software of NRCan, that estimates the ZTD for dual frequency data. The single frequency GPS show a ZTD that is much more variable in time than the ZTD found by dual frequency measurements. Secondly, the standard deviation to which the single frequency measurements converge is about 5 cm. It takes about half a day to obtain this precision. For comparison; the dual frequency receivers obtain a standard deviation well below 1 cm in less than 2.5 hours. The results show this processing method for single frequency receivers is not good enough to obtain an accurate and precise measurement of the ZTD. Further research could be done on taking the correlation between the made observation and generated observations into account, using other processing methods, for instance double differences, or improving this processing method.

precipitable water vapour
GPS
single frequency receiver

http://resolver.tudelft.nl/uuid:ec036b6b-b914-4b53-95f8-63638a0faa10

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Student theses

student report

(c) 2017 Koning, A.M.