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Non-monotonic Eddy Diffusion profile of Titan’s Atmosphere. A Revision from Cassini Observations Cheng Li 1 , X. Zhang 1 , J. A. Kammer 1 , M. C. Liang 2 , Y. L. Yung 1. 1 California Institute of Technology 2 Research Center for Environmental Changes, Academia Sinica , Taiwan. - PowerPoint PPT Presentation
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NON-MONOTONIC EDDY DIFFUSION PROFILE OF TITAN’S ATMOSPHEREA Revision from Cassini Observations
Cheng Li1, X. Zhang1, J. A. Kammer1, M. C. Liang2, Y. L. Yung1
1California Institute of Technology2Research Center for Environmental Changes, Academia Sinica, Taiwan
Photochemistry on Titan
CH4 N2
CH,1CH2,3CH2
CH3
C2H2, C2H4,C2H6
C2H,C2H3,…
C3Hx, C4Hx,…
e-
N2+,N,N+
surface
2
𝑃 −𝐿=− 𝜕𝜕 𝑧 (𝐾 𝑛𝜕𝑥𝜕 𝑧 )
3
Chemical production
Chemical loss
Vertical transport
Eddy diffusivity
Mixing ratio
One dimensional photochemical model
4
C2H2 formation/destruction pathway
5
CIRS limb view and FUV stellar occultationA
ltitu
de
(km
)
CH4
C2H2 C2H4 C2H6
CH3CCH C3H8 C4H2 C6H6
Mixing ratio Vinatier et al., 2009; Kammer et al., 2011
Vinatier et al., 2009; Kammer et al., 2011;
6
No CH4 escape, Koo = 108 cm2 s-1
7
Levenberg–Marquardt
Mixing ratioal
titud
e
C2H2
1000
Retrieval algorithm
8
Molecular diffusivity
Initial guess
Retrieved eddy diffusivity
H2 and C2-hydrocarbons
Higher hydrocarbons
11
Newly detected C3H6
12
Conclusion
13
Back up slides
Dashed Red: CH4 escape = 109 cm-2s-1
Koo = 1.5 x 107cm2s-1
Solid Red:CH4 escape = 0Koo = 1 x 108 cm2s-1
CH4 escape
15
New reaction rate constants (solid lines)
604K / 511K / 400K / 285K / 170K (Titan)
Moses et al.,2000This work
Lightfoot et al., 1987
H + C2H4 + M C2H5 + M
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