Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech),...
-
Upload
blanche-chase -
Category
Documents
-
view
214 -
download
0
Transcript of Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech),...
![Page 1: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/1.jpg)
Organic Synthesis in the Atmosphere of Titan: Modeling
and Recent Observations
Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang
(Caltech), J. Kammer (Caltech), D. Shemansky (SET)
NAI Titan Team Meeting 11-12 May 2011, Pasadena, CA
![Page 2: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/2.jpg)
Outline of Today’s Talk
Titan: gas phase chemistry
Aerosol formation
Surface chemistry
Synergism with lab data
![Page 3: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/3.jpg)
Solar Scattering
Stellar Occultation
J. Ajello
![Page 4: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/4.jpg)
Mixing Ratios of Selected Species from Occultations
![Page 5: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/5.jpg)
UVIS spectrum
Liang et al. 2007
tholin
CH4
Impact: 514 km
![Page 6: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/6.jpg)
Optical Depth Images
![Page 7: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/7.jpg)
c
Lavvas et al. 2008
EUV
FUV
auto
Auto-catalytic process
![Page 8: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/8.jpg)
Hydrocarbon Abundances from TB Encounter
Tholin scale heights above 540 km are larger than any other species indicating formation at high altitudes and downward diffusion.
![Page 9: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/9.jpg)
Photochemical results
Liang, Yung, Shemansky ApJ 2007
CH4; hydrostatic
CH4; non-hydrostaticHC3N
HCN
C6N2
C6H6 C6N2; condensation line
![Page 10: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/10.jpg)
Gu et al. 2009
![Page 11: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/11.jpg)
Model without Haze
![Page 12: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/12.jpg)
![Page 13: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/13.jpg)
C6Hx
![Page 14: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/14.jpg)
![Page 15: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/15.jpg)
Model with Haze Formation
![Page 16: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/16.jpg)
![Page 17: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/17.jpg)
C6Hx
![Page 18: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/18.jpg)
![Page 19: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/19.jpg)
[Vuitton, et al., 2006]
![Page 20: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/20.jpg)
[Vuitton, et al., 2006]
![Page 21: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/21.jpg)
[Vuitton, et al., 2006]
Ion observation
![Page 22: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/22.jpg)
Outline of Today’s Talk
Titan: gas phase chemistry
Aerosol formation
Surface chemistry
Synergism with lab data
![Page 23: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/23.jpg)
Solar Scattering
Stellar Occultation
J. Ajello
![Page 24: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/24.jpg)
Liang et al. 2007
tholinCH4
Impact: 514 km
Stellar Occultation
![Page 25: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/25.jpg)
Qe =−4xI (m2 −1m2 + 2
)
Qs =83
x4 m2 −1m2 + 2
2
x =2πrλ Single Scattering
Albedo (SSA):
SSA = Qs/Qe
Important Parameters
Goody and Yung 1989
![Page 26: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/26.jpg)
Obs: 0.118
16 nm
Refractive Index from Khare and Sagan (1984)
SSA at 1875 Å
![Page 27: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/27.jpg)
Shemansky et al. 2010
![Page 28: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/28.jpg)
. 2Trainer, et al 2006
Tomasko et al. 2008: ~100 km
50 nm radius 3000 monmers
Comparisons
![Page 29: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/29.jpg)
• Tholin Radius at 1040 km: 16 nm
Liang et al. (2007) “guessed” 12.5 nm from Stellar Occultation only
• Comparable to 25 nm (in radius) from Trainer et al. (2006) ; 40 nm from Bar-Nun et al. (2008)
• Lavvas et al. (2008) at 520 km (ISS):
~40 nm
Comparison of radius of tholins
![Page 30: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/30.jpg)
T Tomasko et al. 2008
![Page 31: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/31.jpg)
Outline of Today’s Talk
Titan: gas phase chemistry
Aerosol formation
Surface chemistry
Synergism with lab data
![Page 32: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/32.jpg)
What happens to the Unsaturated
Hydrocarbons at the Surface?
COSMIC-RAY-MEDIATED FORMATION OF BENZENE ON THE SURFACE OF
SATURN’S MOON TITAN
Zhou et al. 2010
![Page 33: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/33.jpg)
Benzene (PAH) Production on
SurfaceCosmic-ray flux on Titan’s surface (φCR =1e9 eV cm−2 s−1)
Yield of benzene from solid acetylene (from lab: Y = 5.6e-3 eV−1)Fraction of the surface of Titan covered by organics (Fo=0.2)
Fraction of organics that is acetylene (Fa=0.2)Time for turnover of the surface by geological processes (τ=2e6 yrs, lowest
estimate )
We get: M = 1.4e19 molecules cm−2
3.4 e−17 g cm−2 s−1
![Page 34: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/34.jpg)
Outline of Today’s Talk
Titan: gas phase chemistry
Aerosol formation
Surface chemistry
Synergism with lab data
![Page 35: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/35.jpg)
Inverse Model
Parameter Estimate
PredictionsAdjoint Forcing
Gradients(sensitivities)
Optimization
Forward Model Adjoint Model
Observations
Improved Estimate
-
t0 tf tf t0
Forward and adjoint models
<-- time evolution profiles
![Page 36: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/36.jpg)
Lab: Adamkovics et al. (2003)
Liang et al. (submitted)
![Page 37: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/37.jpg)
![Page 38: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/38.jpg)
Jupiter (Moses 2005)
![Page 39: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/39.jpg)
Titan (Moses 2005)
![Page 40: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/40.jpg)
References
• Yung, Y. L., M. Allen, and J. P. Pinto. (1984). "Photochemistry of the Atmosphere of Titan: Comparison between Model and Observations." Astrophysical Journal Supplement Series 55(3): 465-506.
• Goody, R. M., and Y.L. Yung, Atmospheric Radiation: Theoretical Basis, 1989, Oxford University Press.
• Yung, Y. L., and W. D. DeMore, Photochemistry of Planetary Atmospheres, 1999, Oxford University Press.
![Page 41: Organic Synthesis in the Atmosphere of Titan: Modeling and Recent Observations Yuk Yung (Caltech), M. C. Liang (Academia Sinica), X. Zhang (Caltech), J.](https://reader030.fdocuments.in/reader030/viewer/2022013012/5697c0251a28abf838cd5516/html5/thumbnails/41.jpg)
Acknowledgements
We appreciate discussions with kinetics groups of Ralf Kaiser and Stan Sander, Mark Allen, Bob West, and support from NASA Cassini, OPR, NAI and PATM.