1 / 17

Variation of CO 2 Absorption Features at 10µm in Venus Upper Atmosphere

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. Overview. Basics and Motivation Data Reduction and Observing Condition Fits and Measurements

kelli
Download Presentation

Variation of CO 2 Absorption Features at 10µm in Venus Upper Atmosphere

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Variation of CO2 Absorption Features at 10µm in Venus Upper Atmosphere Wave Workshop ESTEC / Nordwijk Tobias Stangier November 10th 2011 Ist Physics Institute University of Cologne Tobias Stangier Ist Physics Institute University of Cologne

  2. Overview Basics and Motivation Data Reduction and Observing Condition Fits and Measurements Summary and Outlook Tobias Stangier Ist Physics Institute University of Cologne

  3. Tobias Stangier Ist Physics Institute University of Cologne 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. Tobias Stangier Ist Physics Institute University of Cologne Absorption of CO2 on Venus High abundances of CO2 Low pressure => non-LTE emission features @ 110km Vertical temperature gradient defines pressure induced line broadening Probing the atmosphere between ~60km and 110km

  5. Tobias Stangier Ist Physics Institute University of Cologne 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. Instruments and Telescopes Data acquisition during 7 different observing runs between 2007 and 2011 using • NASA GSFC's • Heterodyne Instrument for Planetary Winds and Composition (HIPWAC) @ • Cologne's • Tuneable Heterodyne Infrared Spectrometer (THIS) @ McMath-Pierce Solar Telescope Kitt Peak, AZ NASA InfraRed Telescope Facility Mauna Kea, HI Tobias Stangier Ist Physics Institute University of Cologne

  7. Tobias Stangier Ist Physics Institute University of Cologne Observing Geometry x May 2007 Nov. 2007 June 2009 • Planetary disc ~ 50% illuminated • FoV = 1.7”, Angular size ~ 20” • Investigation of south polar region

  8. Tobias Stangier Ist Physics Institute University of Cologne • Observing geometry March 2009 • Angular size 33 x 1.7” ~ 56” • Many night-side measurements • Observing CO2(P16) line • Latitudinal and longitudinal variation • Non-LTE features immediately to observe

  9. Radiative Transfer Model CODAT • Initial conditions for model Observing Geometry • Sub-Solar point • Sub-Earth Point etc. • Beam-size on Planet • Transmission of Earth atmosphere State of atmosphere • Kind and abundances of most prominent gases • On Venus CO2 • Temperature profile • In dependence on the pressure level/altitudes Only temperature profile variable! Tobias Stangier Ist Physics Institute University of Cologne

  10. Tobias Stangier Ist Physics Institute University of Cologne Influence of Temperature Profile South pole measurement Freq. res. of 10MHz Divergence of fits to observe LTE model seems to be offset

  11. Temperature Profile • VIRA profile for 85 deg latitude used for model Seiff et. al • Tilted profile by DT~10K at 300 mbar • Warmer atmosphere at lower layers Tobias Stangier Ist Physics Institute University of Cologne

  12. Tobias Stangier Ist Physics Institute University of Cologne Influence of Temperature Profile Tilted temperature profile increases fit quality DTtilt = 10 K Higher SNR improves fit => longer integration time

  13. Tobias Stangier Ist Physics Institute University of Cologne Summary Preliminary analysis of CO2 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. Tobias Stangier Ist Physics Institute University of Cologne 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. Tobias Stangier Ist Physics Institute University of Cologne Thank you for your attention!

  16. Tobias Stangier Ist Physics Institute University of Cologne 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. 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 Tobias Stangier Ist Physics Institute University of Cologne

More Related