Analysis of Tropospheric Correction Models for Local Events within the GSTB Test Case APAF

Achim Hornbostel, Mohammed M. Hoque

Abstract:	The Atmospheric Performance Assessment Facility (APAF) is a Standalone Test Case lead by DLR and performed together with the University of Armed Forces, Munich, in the frame of ESA’s Galileo System Testbed (GSTB-V1). APAF has been responsible to support the tasks of the GSTB V1 Core Element Test Cases by specific products and services related to atmospheric, namely ionospheric, tropospheric and simulation issues. One task of the test case was the evaluation of tropospheric correction models for Galileo users not only with respect to their mean performance but also in case of local events, i. e. extreme local deviations from standard weather conditions or rapid changes of weather conditions. Different models for the tropospheric zenith delay have been compared with 15 years of radiosonde measurements for 11 globally distributed sites and 7 sites in South Asia in order to find the distributions of the residual zenith delay for the different correction models. Additionally, model zenith delays which were derived from meteorological measurements with high temporal resolution have been compared with IGS zenith delays for the site Oberpfaffenhofen, Germany, for selected severe events. The analyzed models include both non-blind models using actual meteorological measurements at the user location, as well as blind models not using such information and relying only on fitting of long-term statistical data. Among the blind models a new blind model proposed by ESA was tested.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	902 - 914
Cite this article:	Hornbostel, Achim, Hoque, Mohammed M., "Analysis of Tropospheric Correction Models for Local Events within the GSTB Test Case APAF," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 902-914.
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