Modelling Propagation Impairments of Earth-Space Links Using Numerical Weather Prediction Tools
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Universite´ catholique de Louvain Ph.D. thesis Modelling propagation impairments of Earth-Space links using Numerical Weather Prediction tools by Laurent Quibus Thesis submitted in partial fulfillment of the requirements for the degree of Docteur en sciences de l’ing´enieuret technologie Composition of the jury Prof. Danielle Vanhoenacker-Janvier – Supervisor UCLouvain, BE Prof. Christophe Craeye – President UCLouvain, BE Prof. Claude Oestges – Secretary UCLouvain, BE Dr. Laurent Delobbe IRM, BE Dr. Rafiq Hamdi IRM, BE Dr. Laurent F´eral U. Toulouse III, FR Louvain-la-Neuve 2020 ii Acknowledgments The content of this work was partially supported by the F.R.S.–FNRS under grant FRFC T.1049.15 (NEWPORT), and by the European Space Agency under the contract ESA4000113886/15/NL/LVH. First, I wish to express profuse thanks to Danielle Vanhoenacker-Janvier, the supervisor of this thesis at UCLouvain. I thank her for accepting me as her PhD student, back in 2015, with the opportunities to work on the NEWPORT project and on the ASALASCA ESA contract. I thank her for her support during the four years and a half that followed, including the chance to partic- ipate in other activities, to attend scientific meetings (EuCAP, ASAPE, ...), and thereof to interact with many scientists in radio-propagation or connected fields. I hardly could have hoped for more understanding, availability, and patience when discussing the progress of the present work and all this entails. I would like to thank the other supervisors of NEWPORT: Rafiq Hamdi and Laurent Delobbe with the Royal Meteorological Institute of Belgium. They both shared their knowledge, regarding Numerical Weather Predictions and weather radars respectively, with great kindness and a communicative pas- sion. I am thankful they accepted to join the thesis committee. My thanks extend warmly to the other researchers who worked on NEWPORT: Rozemien De Troch for providing data from the ALARO model and for undertaking its comparison with the WRF surface fields, and Maryna Lukach for processing Wideumont’s radar data into rain attenuation and for analysing the results. I am very grateful to the other members of the jury for offering some of their time and expertise to evaluate the present work. My thanks go to Claude Oestges, with UCLouvain, for joining the thesis committee and for insisting for a stronger quantitative assessment of the propagation results. My thanks also go to Christophe Craeye, with UCLouvain too, for accepting to preside over the jury. Additional thanks are reserved for Laurent F´eral,with the Universit´e of Toulouse III - Paul Sabatier (FR), who kindly answered the invitation to the jury as an external expert on propagation and its use for NWPs. This thesis would not have been possible without the prior development of a NWP-based simulator of propagation impairments in the wake of the ESA/ESTEC EODDL contract. I wish to acknowledge especially the contri- butions of ONERA (FR) and thank Nicolas Jeannin and Laurent Castanet for providing their source code. I also thank Carlos Pereira, formerly with UCLouvain, for his precious help in getting started with WRF. I owe many thanks to Antonio Martellucci with ESA/ESTEC (NL) for his involvement and leadership regarding ESA propagation activities, most relevantly here the ASALASCA contract and the ASAPE group. I also thank particularly Spiros Ventouras, with STFC/RAL (UK), for his efforts and his feedback as coordinator of the ASALASCA researchers, whom I thank too. I have multiple reasons to express my gratitude towards Carlo Riva and Lorenzo Luini, with PoLiMi (IT). First, I thank them and ASI (IT) for the iii iv Acknowledgments opportunity to test NWP-derived nonrainy attenuation against beacon and radiometric data from the Spino d’Adda station. Second, I thank them for the work on beacon data calibration following Prof. Luini’s visit at UCLouvain. Regarding these activities on beacon data calibration, and about their method with GNSS data, I wish to thank Gustavo Siles, with the Universi- dad Privada Boliviana (BO), and Jos´eManuel Riera, with the Universidad Polit´ecnicade Madrid (ES). I also thank Prof. Riera and Domingo Pimienta del Valle, with UPM as well, for sharing radiometric statistics from Madrid. I thank F´elixCuervo, with Joanneum Research (AT), for his work in com- paring NWP-derived attenuations to beacon and radiometric data in Graz. Also at JR, I thank Joel Fl´aviofor his feedback on the propagation impair- ments simulator. I also thank Michael Schoenhuber and Michael Schmidt. I thank Ondrej Fiser and Viktor Pek, with the Institute of Atmospheric Physics and the University of Pardubice (CZ), and Martin Grabner, with the Czech Metrology Institute (CZ), for the tests on beacon signal processing done at the occasion of Prof. Fiser’s short term scientific mission in UCLouvain. For her extensive work on the nonrainy attenuation during her stay at UCLouvain, and afterwards in India, I also thank Gargi Rakshit, with the University of Calcutta (IN), and I thank her advisor Animesh Maitra. I thank Eric Pottiaux and V´eroniqueDehant, with the Royal Observatory of Belgium, for their help in obtaining and processing GNSS data. I am also highly thankful to Martin Rytir, with the Norwegian Defence Research Establishment (NO), and Terje Tjelta, with Telenor (NO), for the opportunity to work with low-elevation scintillation measurements from Isjord radio. And, for their contribution on this topic during their master’s thesis, I thank Cyriac de Villenfagne de Vogelsanck and Joachim Kervyn de Meerendre. Additionally, I thank Pierre-Yves Gousenbourger and Laurent Jacques, with UCLouvain, for some suggestions regarding interpolation techniques. There is still plenty of my gratitude left for my colleagues at UCLouvain. I thank Alberto Graziani, for his ideas and involvement in ESA activities about beacon signal processing, radiometry, GNSS, and more. I thank Dmitry Ko- valev, for his time spent on the Alphasat station, for sharing this thesis’ tem- plate, for being so helpful and tolerating my presence in an office the longest. I thank Alessandro Vergani and Mojtaba Razavian for their work and collab- oration on beacon data processing, ITU-R models, and NWPs. I thank Pasha Bekhrad for his efforts with NWPs for adaptive optics. I am appreciative for nice interactions with many others: Cleopatra, Jean, Babak, Denis, Thomas, Thomas, Ha, Ferran, Sergei, Evgenii, Igor, Modeste, Julian, Vasilii, Lo¨ıc,Bilel, Husnain, Christopher, Martin, Dimitri, Simon, Maxime, Farzad, ... For their roles in managing the ICTEAM/ELEN computing resources put at work for this thesis, I happily thank Brigitte Dupont and Fran¸coisHubin. I was glad to receive great administrative help from UCLouvain. I thank es- pecially Marie-Christine Vandingenen, Christel Derzelle, and Isabelle Dargent. I wish to also thank the instructors, assistants, technicians, and students of the ”Projet 2” for making my teaching duty a new adventure every year. Finally, I thank my parents, my grandparents, family and friends, for pro- viding perhaps the most important kind of support, if not the kindest even. Abstract Communication channels between the Earth and satellites are in the on-going process to be scaled up to higher and higher carrier frequencies above 20 GHz. The change is driven forward as an increasing number of services fill up the spectral bands allocated at lower frequencies, and as using higher frequencies also results in larger bandwidths, antenna gains and directivity. However, chal- lenges to high frequency transmissions are posed by the stronger impairments of the signal as it propagates through the troposphere. In particular, the power of the signal is attenuated due to the presence of oxygen, water vapour, clouds, rain, and turbulence. The attenuation affects the signal-to-noise ratio (SNR) by up to tens of dB so that Fade Mitigation Techniques (FMTs) become needed. Ideally, the design of FMTs should be based on direct measurements of the attenuation. Earth-space propagation experimental campaigns offer this refer- ence thanks to spaceborne beacons emitting continuously at selected frequen- cies. These experiments are however costly, limited to a few receiving stations in a certain region, and lasting typically only a few years. The stations also require additional equipments such as radiometers in order to obtain the to- tal attenuation and not just the contribution from rain events and amplitude scintillation. There is therefore an interest for models capable to derive the at- tenuation components from alternative measurements, so as to supplement the beacon data or fill the gaps in their coverage. Numerical Weather Predictions (NWPs) are important candidates as they aim to re-create, or even forecast, the state of the atmosphere (pressure, temperature, water, ...) starting with the assimilation of various measurements collected globally. This thesis prin- cipal objective is hence the investigation of the performances of a NWP-based simulator of the attenuation within the context of propagation experiments. The thesis opens by introducing further the problems in Earth-space propa- gation, FMTs, propagation impairments, propagation experiments, and NWPs. A short review of the propagation experiments shows their current limits in frequency (1 to 3, ∼ 20 GHz and < 50 GHz), coverage (mostly temperate), duration (usually ∼ 1 − 5 years), number of stations (from 1 to rarely ∼ 20), and orbits (overwhelmingly geosynchronous orbits (GSO)). A short review of the previous usage of NWPs demonstrates the rarity of results simulated over the long-term (> 1 year), with high resolutions (< 5 km horizontally, < 1 h), or for non-GSO links. It also points out the existence of two methods for the rain attenuation (rain volumetric content or rain rate), and of two methods for the cloud attenuation (NWP parametrisation or Salonen/Mattioli). The thesis continues on the description of the propagation models, NWP models, interpolations or conversion of coordinates, and error metrics involved in the simulation of the attenuation from NWP data and its comparison with other reference datasets (beacon, radiometer, and weather radar).