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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.
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Non-monotonic Eddy Diffusion profile of Titan’s Atmosphere A Revision from Cassini Observations Cheng Li1, X. Zhang1, J. A. Kammer1, M. C. Liang2, Y. L. Yung1 1California Institute of Technology 2Research Center for Environmental Changes, Academia Sinica, Taiwan
Photochemistry on Titan C2H2, C2H4,C2H6 C2H,C2H3,… N2+,N,N+ C3Hx, C4Hx,… CH,1CH2,3CH2 CH3 e- CH4 N2 surface
One dimensionalphotochemical model Chemical production Chemical loss Vertical transport Mixing ratio Eddy diffusivity
Vinatier et al., 2009; Kammer et al., 2011; CIRS limb view and FUV stellar occultation C2H2 C2H4 C2H6 Altitude (km) CH4 CH3CCH C3H8 C4H2 C6H6 Mixing ratio Vinatier et al., 2009; Kammer et al., 2011
Retrieval algorithm 1000 altitude C2H2 Mixing ratio Levenberg–Marquardt
Molecular diffusivity Initial guess Retrieved eddy diffusivity
CH4 escape Dashed Red: CH4 escape = 109 cm-2s-1 Koo = 1.5 x 107cm2s-1 Solid Red: CH4 escape = 0 Koo = 1 x 108 cm2s-1
New reaction rate constants (solid lines) H + C2H4 + M C2H5 + M 604K / 511K / 400K / 285K / 170K (Titan) Moses et al.,2000 This work Lightfoot et al., 1987