Radiative Modeling of the Atmosphere of Neptune Y. Yung 1, X. Zhang 1, R. Shia 1, M. Liang 2, G. Orton 3, A. Mainzer 3 and M. Burgdorf 4 1 Caltech, USA 2 Academia Sinica, Taiwan 3 JPL, USA 4 John Moores University, UK

Motivation 29 AU Sptizer

-Classic P Q R branches from acetylene emission centered at 729 cm -1 -Strong methane absorption into continuum along with some strong emission lines at 1534 cm -1 and 1306 cm -1 -Reflected sunlight dominates frequencies higher than ~1400 cm -1 -All emission lines sitting on top of H 2 collision induced continuum Acetylene (C 2 H 2 ) Ethane (C 2 H 6 ) Ethylene (C 2 H 4 ) Methane (CH 4 ) IRS Cycle 2 Spectrum

Chemical Transport Modeling

Atmospheric Structure

Radiance

Heating/Cooling Rate

Heating Rate Sensitivity

Cooling Rate Sensitivity

Aerosol (tholin)? Cross Section: Coefficients n &k from Khare et.al.[1984]

Aerosol Profile –Above 1 mbar –Constant number density Cross Section r = 125 A

Heating Rate with Aerosol 3

Cooling Rate with Aerosol

Conclusion Spitzer observations provide new constraints for chemical and radiative processes in the atmosphere of Neptune Imbalance in heating and cooling suggest, most likely, the existence of aerosols in the middle-upper atmosphere

Not Used

Eddy Sensitivity (… 5x eddy x eddy)

Cooling Rate with Aerosol(2) the blue line bottom is heating! So cannot plot out, maybe we shall not show this line this time

Radiace Sensitivity

Radiative Transfer Model Shortwave Heating: Solar energy absorption by CH4 Radiance and Longwave Cooling : Thermal radiation of atmosphere and absorption by species Heating cm -1 Cooling cm -1