Improved dry tropospheric propagation delay mapping function for GPS measurements in Egypt

Abstract

A large number of models and mapping functions have been developed for use in the analysis of space geodetic data. The performance of tropospheric delay prediction models used for GPS degrades at very low elevation angles. On the other hand, most standard tropospheric models were experimentally derived using available radiosonde data, which were mostly observed on the European and North American continents. In this paper an investigation is presented of several models, including those developed by Hopfield, Saastamoinen, Niell (NMF), Chao, Black & Eisner (B&E), Yan & Ping, Vienna (VMF) and Isobaric (IMF), to determine the errors of these models in predicting dry tropospheric delay and to present a new mapping function which has better low elevation angle performance up to 5° and is suitable for the atmospheric conditions of Egypt. A very significant improvement in the GPS height component can be achieved by using the new mapping function especially for the atmospheric conditions of Egypt.

Keywords::

• Egypt
• EMA
• mapping function
• new mapping function

Acknowledgements

The author thanks all members of the Egyptian Meteorological Authority for preparing, realising and analysing the measurements of Temperature, Pressure and Humidity with different heights within their authority. The support of the department is gratefully acknowledged.