Accurate and fast computation of the radiative transfer absorption rates for the infrared bands in the atmosphere of Titan
In order to accurately interpret the infrared emissions measured by instrumentation a board satellites, dedicated algorithms must be developed to take into account that the atmospheric compounds not always emit according to the Planck function at the local kinetic temperature. These algorithms (non-LTE models) must include a complete set of radiative and collisional processes affecting each emitter level and gas in the atmosphere in order to compute the population of these levels by solving the set of coupled radiative transfer and gas-specific steady state equations. In particular the treatment of the radiative transfer for opticaly thick bands (exchange of photons among the atmospheric layers and between these and the planet's surface) is a critical problem in the solution of the system, determining the accuracy and speed of the calculation. In the case of the Titan atmosphere, the treatment of the radiative transfer is specially important for the CH_4, C_2H_2, C_2H_6, and HCN ro-vibrational bands. In this paper we present a study of the impact of: i) the different treatment of the coupling between the radiative transfer and steady state equations; and ii) the different approachs to the treatment of the radiative tranfer (Curtis matrix formulation, Lambda-iteration and accelerated Lambda-iteration techniques,...) in the accuracy and CPU time required of the calculations in the atmosphere of Titan.
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003