Publicação
Dynamics of Venus' atmosphere: wind characterization with Doppler velocimetry
| Resumo: | The most relevant aspect of the general circulation of the atmosphere of Venus is its retrograde super-rotation. A full characterization of the zonal winds is crucial to understand this movement and the mechanisms that maintain it. This thesis analyzes data from coordinated wind amplitude and variability measurements at Venus cloud-tops based on the two complementary techniques of Ground-based Doppler velocimetry(Widemann etal., 2007, 2008; Machado etal., 2012, 2014), using the ESPaDOnS instrument (Echelle SpectroPolarimetric Device for the Observation of Stars) at CFHT(Canada France Hawaii Telescope),and cloud-tracked winds using ESA Venus Express/VIRTIS- M (Visible and Infrared Thermal Imaging Spectrometer) imagingat0.38 µm (Drossart etal., 2007; Sánchez-Lavega etal., 2008; ?; Machado etal., 2014). We performed a new coordinated campaign in April 2014 combining both Venus Express observations and ground-based Doppler wind measurements on the dayside of Venus'cloud tops at CFHT at a phase angle ϕ =(76±0:3)ᵒ. The analysis and results show (1) additional confirmation of the complementarity, on both spatial and temporal time scales, of the two techniques ;(2) evidence of a symmetrical, poleward meridional Hadley flow in both hemispheres of vm = 22.5±15.5 ms1; (3) spatial and temporal variability of the zonal flow with latitude and local time, with a significant increase of wind amplitude near morning terminator already reported in Feb.2011observations. This work complements the independent observations of the european space mission Venus Express and is part of the effort made by the scientific community in the area of planetology to understand the dynamics of the atmosphere of Venus. |
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| Autores principais: | Gonçalves, Ruben Henrique Machado |
| Assunto: | Vénus Atmosferas Velocimetria de Doppler Vento zonal Vento meridional Super-rotação Teses de mestrado - 2016 |
| Ano: | 2016 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | The most relevant aspect of the general circulation of the atmosphere of Venus is its retrograde super-rotation. A full characterization of the zonal winds is crucial to understand this movement and the mechanisms that maintain it. This thesis analyzes data from coordinated wind amplitude and variability measurements at Venus cloud-tops based on the two complementary techniques of Ground-based Doppler velocimetry(Widemann etal., 2007, 2008; Machado etal., 2012, 2014), using the ESPaDOnS instrument (Echelle SpectroPolarimetric Device for the Observation of Stars) at CFHT(Canada France Hawaii Telescope),and cloud-tracked winds using ESA Venus Express/VIRTIS- M (Visible and Infrared Thermal Imaging Spectrometer) imagingat0.38 µm (Drossart etal., 2007; Sánchez-Lavega etal., 2008; ?; Machado etal., 2014). We performed a new coordinated campaign in April 2014 combining both Venus Express observations and ground-based Doppler wind measurements on the dayside of Venus'cloud tops at CFHT at a phase angle ϕ =(76±0:3)ᵒ. The analysis and results show (1) additional confirmation of the complementarity, on both spatial and temporal time scales, of the two techniques ;(2) evidence of a symmetrical, poleward meridional Hadley flow in both hemispheres of vm = 22.5±15.5 ms1; (3) spatial and temporal variability of the zonal flow with latitude and local time, with a significant increase of wind amplitude near morning terminator already reported in Feb.2011observations. This work complements the independent observations of the european space mission Venus Express and is part of the effort made by the scientific community in the area of planetology to understand the dynamics of the atmosphere of Venus. |
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