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Delve into the impact of methane concentration on Titan's atmosphere equilibrium post-abrupt climate change. Analyze one-dimensional models to understand methane dynamics and atmospheric dynamics, paving the way for future improved modeling.
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Abrupt Climate Change on Titan Jeff Portwood B.S. Geophysics and Space Physics, UCLA CSI Intern
Outline • Brief survey of Titan • Motivation • Model • Radiation Scheme • Effects of Methane on Equilibrium Temperature • Future adjustments of Model
Titan • Saturn’s largest moon • Thick atmosphere • 95.1% N2 • 4.9% CH4 • Hydrocarbon lakes near poles • Fluvial erosion features across the surface • Methane rain • “Wet” versus “dry” climate
Motivation • Mitchell [2008] showed a possibility of multiple climate equilibria following abrupt climate change on Titan • I will further explore the effect that various levels of methane concentrationshave on the dynamics of the atmosphere using a simpler one-dimensional mode • Model Hierarchy: step up for realism, step down for understanding Mitchell [2008]
Model • One-dimensional radiative-convective model • Useful for modeling planetary heat budget • Lacks horizontal heat transport and latitudinal redistribution of methane • Highlights the importance of the thermodynamics of methane evaporation and condensation
Energy Balance 55% 100% 45% S 30% 15% T SW absorption 10% 113% 120% 2% 1%
Dry Convection vs. Moist Convection Observed Dry Adiabat Moist Adiabat Pressure [mbar] ~90 ~94 Temperature [K]
Abrupt Climate Transition Addition/Removal of surface methane produces a transition in surface equilibrium temperature
Wet and Dry Temperature Profiles Ts (dry) ~ 93 K Ts (wet) ~ 91 K
Future goals • Many parameters to be looked at in more detail • Diffusion • Boundary Layer • Huygens fluxes • McKay et al. 1991 in good agreement with Huygen’s landing site • Increasing the speed of the model • Each run takes ~7 hours • Build simplified two-dimensional model • Allow for horizontal heat transport