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Characterization of the Dynamics of the Atmosphere of Venus with Doppler Velocimetry Pedro Miguel Borges Do Canto Mota Machado

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Characterization of the Dynamics of the Atmosphere of Venus with Doppler Velocimetry Pedro Miguel Borges Do Canto Mota Machado Characterization of the Dynamics of the Atmosphere of Venus with Doppler velocimetry Pedro Miguel Borges Do Canto Mota Machado To cite this version: Pedro Miguel Borges Do Canto Mota Machado. Characterization of the Dynamics of the Atmosphere of Venus with Doppler velocimetry. Astrophysics [astro-ph]. Observatoire de Paris; Université de Lisbonne, 2013. English. NNT : 2013OBSP0270. tel-02337921 HAL Id: tel-02337921 https://hal.archives-ouvertes.fr/tel-02337921 Submitted on 4 Nov 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. UNIVERSIDADE de LISBOA OBSERVATOIRE de PARIS FACULDADE de CIÊNCIAS da ÉCOLE DOCTORALE ASTRONOMIE ET UNIVERSIDADE de LISBOA ASTROPHYSIQUE D'ILE-DE-FRANCE Doutoramento em Astronomia e Astrofisica Doctorat en Astronomie et Astrophysique Pedro Miguel Borges do Canto Mata MACHADO 2013 !I !I 1 Characterization of the Dynamics of the Atmosphere of Venus with Doppler velocimetry Thèse dirigée par David Luzet Thomas Widemann Tese orientada por David Luze Thomas Widemann Soutenue le 2 Décembre 2013 devant un jury composé de: Tese defendida a 2 de Dezembro de 2013 perante o juri: Didier Pelat (LUTH - Obs. de Paris) Président du Jury Robert Todd Clancy (Space Science lnstitute) Rapporteur Wojciech Markiewicz (Max-Planck-Institut für Aeronomie) Rapporteur Thérèse Encrenaz (LESIA - Obs. de Paris) Examinateur Giuseppe Piccioni (INAF - IAPS) Examinateur José Afonso (CAAUL/FCUL - Universidade de Lisboa) Examinateur David Luz (CAAUL/FCUL - Universidade de Lisboa) Directeur de thèse Thomas Widemann (LESIA- Obs. de Paris) Directeur de thèse UNIVERSIDADE de LISBOA OBSERVATOIRE de PARIS FACULDADE de CIÊNCIAS da ÉCOLE DOCTORALE ASTRONOMIE ET UNIVERSIDADE de LISBOA ASTROPHYSIQUE D’ILE-DE-FRANCE Departamento de Física Characterization of the Dynamics of the Atmosphere of Venus with Doppler velocimetry Pedro Miguel Borges do Canto Mota MACHADO PhD in Astronomy and Astrophysics 2013 UNIVERSIDADE de LISBOA OBSERVATOIRE de PARIS FACULDADE de CIÊNCIAS da ÉCOLE DOCTORALE ASTRONOMIE ET UNIVERSIDADE de LISBOA ASTROPHYSIQUE D’ILE-DE-FRANCE Departamento de Física Characterization of the Dynamics of the Atmosphere of Venus with Doppler velocimetry Pedro Miguel Borges do Canto Mota MACHADO Thesis directed by Dr. David Luz and Dr. Thomas Widemann, specially elaborated to obtain the degree of PhD in Astronomy and Astrophysics. 2013 ii iii “Nous nous découvrions, nous aussi, emportés vers un avenir ignoré, à travers la pensée des vents...” Antoine de Saint-Exupéry (Terre des hommes) iv Aknowledgements Along this long journey I was so fortunate that I had two beacons who helped me finding a safe way. The winds are not always peaceful. There are storms and hurricanes, tornadoes and dangerous shallows which can sink the boat. It is true that now I just feel a gentle breeze swelling my boat’s sails. It is true that I smile listening the whistle of the wind...now returning to harbour after having gave name to blank territories in old maps...I return from a harsh voyage, but I kept the love for sailing...and for the wind. I am already started dreaming about the next destination. There is no such thing as an old wind...the wind is always new, always fresh... I am grateful to my supervisors David Luz and Thomas Widemann. They were always a reference and an example of dedication and seriousness as scientists, always preserving an ethical and responsible attitude. I learned a lot with them, and I thank them for their patience and availability. We worked hard but the atmosphere was always dynamic and vibrant of joy. It was a privilege belonging to a crew which captain loves his job. Now I feel I am a much better sailor and I am eager to resume the navigation in the deep seas of science. It was a real privilege for me to work at the Observatoire de Paris. It was also a pleasure to work there. To my dear colleagues, I leave here a friendly hug, and I will remember with delight the spirit of mutual help, which has always reigned amongst us. My debt of gratitude to several researchers and staff is huge and I will remember with affection all the help and sympathy that they always provided me. The Lisbon Observatory was the place that saw my first steps on sci- ence...so, it is my home, to which I am very happy to return. The Lisbon’s Center of Astronomy and Astrophysics (CAAUL) is a pleasant and wonderful place to work, always full of enthusiasm. It seems that each one that works there is a brick in the building walls. It was an honour for me that such distinguished jury accepted to partic- ipate in this decisive stage of my life. I am very happy for that and I hope that I deserved their time and attention. I acknowledge all elements of the v vi AKNOWLEDGEMENTS jury, specially the two rapporteurs, for the attention dedicated to this thesis. I will be always grateful to my wife, Patrícia, for amplifying all that I am and by valuing what I care about. She endured this true marathon with a generous and compassionate spirit. Despite my frequent absences she was always present and the restoring force towards her was enhanced by the distance, even in a direct proportion. My dear sons, Miguel and Filipe remained my beloved friends, despite all those nights I could not tell them stories to sleep. And for not forgetting me, even if I was so often away from their cheerful company. My journey would not have been possible without the many people who cheered me on and helped me through the grey tough days. I am deeply grateful to my dear friend Eddie, that welcomed me in his house, were I felt always a warm and friendly atmosphere. I will always remember our philosophical chats and the cultural life that we shared together. It was very funny sailing together...the wind is always a pleasant bond. I thank him for the lasting encouragement, kind hospitality, and words of motivation with which I breathed the will and dedication. He will remain in my heart as a wonderful person. To my parents, Jacinto Machado and Julia, by having instilled on me the taste for mathematics and science in general. I am grateful to them for having developed and amplified on me a sharp curiosity for knowledge, by having helped me developing a cultural and artistic sensibility and encouraged me in choosing as a major goal, the pursuit of wisdom. A special word to my mother in law, Josefa, to whom I owe having had the possibility of being absent so often, without harming too much the stability of my family. I thank her for her patience and dedication. I would like dedicate a special thanks to my colleagues, researchers and friends who have supported and helped me from the very beginning of this true marathon. I highlight Javier Peralta, João Retrê, Emmanuel Lellouch, Sanjay Limaye, Bruno Siccardi, Francoise Roques, Manuela Sornig, Brad Sandor, Dimitri Titov, Agustin Sánchez-Lavega, Ricardo Hueso, Felipe Braga Ribas, Maryam El Moutamid, João Lin Yun, Rui Agostinho, Eliot Young, Lucie Maquet, Quentin Kral, J.F. Donati, Y. Matsuda and Masahiro Takagi for the helpful and useful advice, fruitful suggestions and for many valuable discussions. I would also like to extend my gratitude to all the exceptional teachers that provided me accurate knowledge, extremely useful tools, helped to de- velop my scientific background, and a critical and ethical sense. They showed me how science can be fun, relevant and honest. With their help now I feel that the universe, in addition to being fascinating, can be great fun. I acknowledge the Fundação Luso-Americana para o Desenvolvimento vii (FLAD) for the travel grant which they attributed to me. I also acknowledge the support of the Portuguese Foundation for Science and Technology (FCT) for providing me the opportunity and the financial support to carry out the research presented in this thesis by the funding of the PhD grant (reference: SFRH/BD/66473/2009). viii AKNOWLEDGEMENTS Abstract Currently the study of the Venus’ atmosphere grows as a theme of major interest among the astrophysics scientific community. The most significant aspect of the general circulation of the atmosphere of Venus is its retrograde super-rotation. A complete characterization of this dynamical phenomenon is crucial for understanding its driving mechanisms. This work participates in the international effort to characterize the at- mospheric dynamics of this planet in coordination with orbiter missions, in particular with Venus Express. The objectives of this study are to investigate the nature of the processes governing the super-rotation of the atmosphere of Venus using ground-based observations, thereby complementing measure- ments by orbiter instruments. This thesis analyzes observations of Venus made with two different in- struments and Doppler velocimetry techniques. The first part of the thesis presents ground-based Doppler velocimetry measurements of the zonal winds based on observations carried out with the Ultraviolet and Visual Echelle Spectrograph at ESO’s Very Large Telescope. Using Doppler-shifted Fraunhofer lines from the solar spectrum, this high res- olution spectrograph (R ∼ 100,000) allows to measure the velocity of Venus’ upper cloud layer with a precision of about 5 ms−1. Under the assumption of predominantly zonal flow, this method allows the simultaneous direct mea- surement of the zonal velocity across a range of latitudes and local times in the day side.
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