Analysis of Titan's atmospheric circulation with the new IPSL Titan GCM
Abstract
The new IPSL Global Climate Model for Titan's atmosphere is presented, using the current version of the LMDZ GCM dynamical core with the physics of the IPSL Titan 2-dimensional climate model. Modifications in the boundary layer scheme has yielded strong improvements in the tropospheric zonal wind and potential temperature profiles modeled at Huygens descent position and season. The latitudinal profile of the near-surface temperature is close to observed values. The minimum of zonal wind observed by the Huygens probe just above the tropopause is also present in these simulations, and its origin is discussed by comparing solar heating and dynamical transport of energy. The stratospheric temperature and wind fields are consistent with our previous works. Compared to observations, the zonal wind peak is too weak (around 120 m/s) and too low (around 200 km). The temperature structures appear to be compressed in altitude, and depart strongly from observations above 300 km. These discrepancies are correlated, and most probably related to the altitude of the haze production (1 Pa), producing a detached haze layer located 150 km lower than observed by the Cassini instruments. This low production is due to the current limitations of the GCM at high altitudes. However, the temporal behaviour of the detached haze layer in the model may help understand the seasonal differences observed between the Cassini and Voyager 1 seasons. The tides and waves present in the GCM are analysed, together with their respective role in the angular momentum budget. Though the role of the mean meridional circulation in momentum transport is similar to previous work and the transport by barotropic waves is clearly seen in the stratosphere, a significant part of the transport at high latitudes is done all year long through low-frequency tropospheric waves, possibly baroclinic waves.
- Publication:
-
EPSC-DPS Joint Meeting 2011
- Pub Date:
- October 2011
- Bibcode:
- 2011epsc.conf..146L