Radiative Modeling of the Atmosphere of Neptune Y

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

Ethylene (C 2 H 4) Methane (CH 4) Ethane (C 2 H 6) Acetylene (C 2 H 2) IRS Cycle 2 Spectrum -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

Chemical Transport Modeling

Chemical Transport Modeling

Atmospheric Structure

Radiance

Heating/Cooling Rate

Heating Rate Sensitivity

Cooling 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 middleupper atmosphere

Not Used

Eddy Sensitivity (… 5 x eddy --- 0. 1 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 CH 4 • Radiance and Longwave Cooling : Thermal radiation of atmosphere and absorption by species Heating 1000 -50000 cm-1 Cooling 100 -2000 cm-1