Hiromu Nakagawa 2 Naoya Hoshino 2 M anuela Sornig 1 Guido Sonnabend 3 Dusan Stupar 3

1. Venus Upper Atmosphere: Doppler Wind Variations and Comparison with Wave Modeling Hiromu Nakagawa2 Naoya Hoshino2 Manuela Sornig1 Guido Sonnabend 3 Dusan Stupar3 RIU, Department for Planetary Science, University of Cologne, Germany Deparment of Geophysics, Tohoku University, Sendai, Japan I.Physikalisches Instiut, University of Cologne, Germany Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

2. Outline: • Introduction / Motivation • Model Overview main features; limitations • Data abilities; limitations • Comparison • Outlook & Summary Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

3. Introduction: University of Cologne I.Physikalisches Institut Cologne, Germany Tohoku University Department of Geophysics Sendai, Japan - building a heterodyne instrument - modeling running heterodyne instrument since ~2003 Cooperation comparison of “our” data to “their” model Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

4. Model Characteristics: Hoshino et al, Icarus, 2011 • 80 to 180km • resolution 10x20x1 long,lat,height • considering planetary scale waves Kelvin & Rossby waves, Diurnal and Semi-diurnal tides • Solar EUV flux • Eddy diffusion coefficient • Rayleigh friction • 15-um CO2 cooling effect • lower boundary: horizontal and vertical wind velocities are assumed to be 0m/s • integration time is 80earth days; time step 10s • geopotential fluctuation at lower boundary is included Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

5. Model Output: • temperature distribution • wind velocities • number density (O,CO,CO2) Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

6. Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne Model Results: first time: examination of vertical propagation of planetary-scale waves in the mesosphere

7. Data Basics:  non-LTE CO2 emission line at 10 μm  induced by solar radiation - dayside!  narrow line width: ~40MHz integration time: 20 min Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

8. Data Basics:  emission origins within a small pressure region @ 1microbar = ~ 110km  altitude information from model calculation (Lopez-Valverde et al, PSS 2010) 110 ± 10km Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

9. intensity intensity frequency intensity frequency frequency Data Output:  precise frequency determination  narrow CO 2emission line at 10µm  Doppler-shift "line of sight" velocity 1MHz ~ 10m/s  resolved non-LTE emission line  provides line width  Doppler equation provides kin. temp.  precision up to 5K Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

10. Data Parameter:  “good” spatial resolution  “good” temporal coverage  direct line-of-sight winds  kinetic temperatures  maybe in the future: wind profiles (CO2 absorption lines) • “on request” ☺ • integration time: < 20min • hours, days, weeks, month • long term possible!!! years, decades, generation... Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

11. Comparison: Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

12. Comparison: • there is wave propagation up to 110km which agrees with the model • latitudinal dependency can be seen in model & observations → higher lat = lower wind • no phase change indication in the model • wind amplitude can not be reproduced by the model Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

13. Model Investigations: • Rayleigh friction • 15 mue cooling • boundary conditions / background wind • parametrization Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

14. Rayleigh friction: Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

15. Comparison: The most significant change can be seen in the night side region. Enhancement of the wind fluctuations, approximately 15 m/s with Rayleigh friction coefficient change Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

16. Model Investigations: • Rayleigh friction • 15 mue cooling • boundary conditions / background wind • parametrization Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

17. Summary & Outlook: • model investigations: • lower boundary (including superrotation) • including gravity waves • parametrization • data investigations: • add. observations for longer period • including other observation • for comparison • and boundary conditions • there is wave propagation up to 110km which agrees with the model • latitudinal dependency can be seen in model & observations • no phase change indication in the model • wind amplitude can not be reproduced by the model Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne

18. The End: Hiromu Nakagawa Naoya Hoshino Thank you !!! questions concerning model: rom@pat.gp.tohoku.ac.jp / hoshino@pat.gp.tohoku.ac.jp Manuela Sornig [1] RIU – Department of Planetary Science [2] I.Physikalisches Institut, University of Cologne