1. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 1 Variation of CO 2 Absorption Features at 10µm in Venus Upper Atmosphere Wave Workshop ESTEC / Nordwijk Tobias Stangier November 10 th 2011 I st Physics Institute University of Cologne

2. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 2 Overview Basics and Motivation Data Reduction and Observing Condition Fits and Measurements Summary and Outlook

3. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 3 Motivation State of the art: ›Determination out of the non-LTE line profile →Line-of-sight wind speeds →Kinetic temperatures ›But we can do better more than that! →Non-LTE solar induced => only present on Venusian day side ›Measurements on night side →No non-LTE emission features overlaying the absorption

4. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 4 Absorption of CO 2 on Venus ›High abundances of CO 2 ›Low pressure => non-LTE emission features @ 110km ›Vertical temperature gradient defines pressure induced line broadening ›Probing the atmosphere between ~60km and 110km

5. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 5 Heterodyne – the unique technique ›Ultra high frequency resolution enables to resolve single line profiles ›Probing the mid-Infrared spectral region 7-11µm ›Higher spatial resolution than at radio-frequency →Beam size many times smaller than planetary disc →Longitudinal and latitudinal profiling possible

6. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 6 Instruments and Telescopes ›Cologne's →Tuneable Heterodyne Infrared Spectrometer →Tuneable Heterodyne Infrared Spectrometer (THIS) @ ›NASA GSFC's →Heterodyne Instrument for Planetary Winds and Composition →Heterodyne Instrument for Planetary Winds and Composition (HIPWAC) @ Data acquisition during 7 different observing runs between 2007 and 2011 using McMath-Pierce Solar Telescope Kitt Peak, AZ NASA InfraRed Telescope Facility Mauna Kea, HI

7. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 7 Observing Geometry x June 2009Nov. 2007May 2007 ›Planetary disc ~ 50% illuminated ›FoV = 1.7”, Angular size ~ 20” ›Investigation of south polar region

8. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 8 ›Observing geometry March 2009 ›Angular size 33 x 1.7” ~ 56” ›Many night-side measurements ›Observing CO 2 (P16) line ›Latitudinal and longitudinal variation ›Non-LTE features immediately to observe

9. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 9 Radiative Transfer Model CODAT State of atmosphere -Kind and abundances of most prominent gases -On Venus CO 2 →Temperature profile -In dependence on the pressure level/altitudes Observing Geometry -Sub-Solar point -Sub-Earth Point etc. -Beam-size on Planet -Transmission of Earth atmosphere ›Initial conditions for model Only temperature profile variable!

10. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 10 Influence of Temperature Profile ›South pole measurement ›Freq. res. of 10MHz ›Divergence of fits to observe ›LTE model seems to be offset

11. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 11 Temperature Profile ›VIRA profile for 85 deg latitude used for model Seiff et. al ›Tilted profile by  T~10K at 300 mbar ›Warmer atmosphere at lower layers

12. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 12 Influence of Temperature Profile ›Tilted temperature profile increases fit quality ›  T tilt = 10 K ›Higher SNR improves fit => longer integration time

13. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 13 Summary ›Preliminary analysis of CO 2 absorption lines at 10 micron ›Strong variation of absorption profile detected ›Pressure induced broadening effects give hint on temperature ›Influence of vertical temperature profile under investigation ›Fit results improved if profile is slightly tilted →Strong effect even for small changes

14. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 14 Outlook ›Coordination with RadioScienceExperiment ›Ground-based measurements of a vertical temperature profile →High spatial resolution in the mid-IR →Longer integration time to achieve higher SNR ›Vertical wind profiles → Wind shear between atmospheric layers -Transition between super-rotation and SS-AS flow dominated regions -Wave propagation ›Detailed investigation of longitudinal and latitudinal variation ›Continuous long-term observation →Seasonal behavior? →Especially at south-pole

15. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 15 Thank you for your attention!

16. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 16 Temperature Profiles ›First step: influence of the temperature profiles →VEX:RadioScience Experiment on board of VenusExpress (Tellmann et al.) →VIRA from Seiff et al. and Keating et al. →VEX temperature lower

17. Basics & Motivation Technique & Observations Fits & Measurements Summary & Outlook Atmospheric Wave Workshop ESTEC 11/10/2011 Tobias Stangier I st Physics Institute University of Cologne Slide: 17 Resulting Fits ›south pole measurement @ 10MHz resolution ›slight difference between fits to observe ›absorption depth of LTE model dependent of temp. profile ›poor signal to noise ratio →longer integration time required