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GNSS meteorology in spatially dense networks / Fabian Peter Hurter (2014)

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Titre :	GNSS meteorology in spatially dense networks
Type de document :	Thèse/HDR
Auteurs :	Fabian Peter Hurter, Auteur
Editeur :	Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse
Année de publication :	2014
Collection :	Astronomisch-Geodätische Arbeiten in der Schweiz, ISSN 0025-6676 num. 91
Importance :	185
Format :	21 x 30 cm
ISBN/ISSN/EAN :	978-3-908440-37-6
Note générale :	Bibliographie
Langues :	Anglais (eng)
Descripteur :	[Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Bernese [Termes IGN] données GNSS [Termes IGN] météorologie [Termes IGN] propagation du signal [Termes IGN] retard troposphérique zénithal [Termes IGN] signal GNSS [Termes IGN] station GNSS [Termes IGN] station météorologique [Termes IGN] teneur en vapeur d'eau [Termes IGN] traitement du signal
Index. décimale :	30.84 Applications de géodésie spatiale à l'atmosphère
Résumé :	(auteur) Two basic products from GNSS meteorology have been investigated in detail: (a) the Zenith Total Delay (ZTD) and, (b) wet refractivity fields reconstructed from Zenith Wet Delays (ZWD).The thesis aims at quantifying the accuracies of GNSS-derived ZTDs and refractivities and at characterizing their temporal and spatial resolution. In a first study using operational radiosondes and Global Navigation Satellite System (GNSS) data from the Swiss meteorological station in Payerne, the following uncertainty figures are obtained: With respect to the radiosonde, the GNSS-derived ZTD has a 1–3mm dry bias. Annual systematic variations of the comparison are found to have an amplitude of 1–2 mm . Removal of most systematic effects from the GNSS minus radiosonde ZTD time series plus a thorough budget of the radiosonde uncertainties allows the derivation of the random GNSS uncertainties. In the winter half-year, the standard deviation is shown to be 2.5–3.5 mm , during the summer half-year we obtain 3.5–5.0 mm. In a further study in the western part of Switzerland, wet refractivities have been derived on the basis of interpolated ZWDs from the Automatic GNSS Network for Switzerland (AGNES). The employed interpolation algorithm is termed least-squares collocation. It makes use of a deterministic function to describe the general parametric field and a correlation function describing the spatial and temporal correlations between the zenith wet delays. Corresponding wet refractivities show accuracies superior to results from tomographic reconstructions of a similar data set. Further inclusion of ground meteorological measurements of temperature and water vapour pressure im- prove the derived refractivities in the lowest 2 km of the troposphere. Radio occultations are added to the reconstruction. The data combination enables the extension of the radio occultation profiles down to the ground. It is also shown that the GNSS data largely contributes to the profile quality above the atmospheric boundary layer. Transformation of the wet refractivities to humidity values with temperature profiles from a radiometer in Payerne show accuracies of a similar order of mag nitude to those from numerical weather prediction analysis. Hence, application of the algorithm in nowcasting of rain or investigating boundary layer processes are envisaged. The third part of the thesis investigates the results from a campaign network of 34 geodetic- grade receivers. They were deployed close to and around Zermatt (Switzerland) for one month in summer 2010. The stations were spaced at distances of a few kilometers from each other and at heights between 1600–3500 m above mean sea level. The mountainous region provides an excellent natural laboratory to investigate the influences affecting the accuracy of the ZTD. Additionally, the Alpine region is prone to small-scale fluctuations in the troposphere. Thus, the spatial and temporal variability of the ZTD has been investigated. The influences of satellite obstructions, antenna and receiver types and a number of processing strategies on the estimated ZTD are analysed and validated with measurements from radiosondes launched during the campaign. The analysis suggests that 1 hour temporal resolution should not be undercut for estimated ZTDs. A temporal resolution of 30 minutes introduces more noise without better following the tropospheric fluctuation. The horizontal variability observed in ZTDs indicates correlation scale lengths of a few kilometers. From comparison with radiosondes, the ZTD uncertainty is shown to have 4–6 mm standard deviation. Some stations show signs of systematic effects caused by multipath and low- quality antenna patterns. Through the GNSS-inherent negative correlation of height with zenith delay, both parameters are similarly affected by these systematic influences. The performance of the numerical weather prediction model COSMO-2 is characterized in terms of integrated atmospheric state. The analysis yields preliminary recommendations on the assimilation of zenith total path delays into weather models in regions of highly complex topography such as the Swiss Alps.
Note de contenu :	1 Introduction 1.1 Review of GNSS meteorology 1.2 Potential synergies with other water vapour measurements . 1.3 Challenges in GNSS meteorology 1.4 Objectives and structure of the thesis 2 Theory 2.1 Refractivity and path delay in the atmosphere 2.2 Collocation with the software COMEDIE 2.3 Water vapour tomography software AWATOS2 3 Comparison of zenith path delays from GNSS and radiosonde measurements 3.1 Data description 3.2 Formal uncertainties of ZTD estimates from GNSS 3.3 Comparison of ZTDs 3.4 Influence of processing strategy on GNSS ZTDs 3.5 2nd and 3rd order ionospheric effects . 3.6 Comparison of ZWDs 3.7 Formal uncertainty of radiosonde-derived ZTDs 3.8 Derivation of random GNSS ZTD uncertainty 3.9 Correlation between GNSS heights and ZTDs 3.10 Discussion . 3.11 Conclusion . 4 Payerne profile study 4.1 Abstract 4.2 Introduction 4.3 Description of data sets 4.4 Processing 4.5 Results . 4.6 Discussion 4.7 Conclusions 5 Geodetic water vapor campaign in Zermatt 5.1 Data description and processing 5.2 Troposphere results 5.3 Conclusions 6 Conclusions
Numéro de notice :	12952
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Thèse étrangère
En ligne :	http://www.sgc.ethz.ch/sgc-volumes/sgk-91.pdf
Format de la ressource électronique :	URL
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=76823

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
12952-01	30.84	Livre	Centre de documentation	Géodésie	Disponible

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2014 -2024 IGN

Centre de documentation
scientifique