High altitude haze: Influence of monomer particles on Titan's temperature profile

The present study investigates the role of high altitude monomer particles in the energy balance of Titan's upper atmosphere above an assumed low and high aggregate formation altitude of 385 km and 535 km. A 'single particle approach' was applied, where the starting point is the energy balance of an individual aerosol. In our analysis 0.01-0.06 mu m radius aerosol particle s were chosen for the proposed monomer formation regions. These particles a bsorb solar radiation, emit in the infrared, and are energetically linked t o the surrounding gas by thermal conduction. To compute the monomer particl e heating effect, the aerosols are assumed to radiate directly to space. We found that high altitude monomers may affect the profile of Titan's thermo sphere from 2 to 20 K depending on the formation altitude of fluffy non-sph erical aggregates, the monomer size and distribution. The actual Titan temp erature profile in this altitude range including all heating effects will b e measured by the HASI instrument during the descent of the Huygens probe. (C) 1999 Elsevier Science Ltd. All rights reserved.