Computer Science
Scientific paper
Jul 1998
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998phdt........15d&link_type=abstract
Thesis (PHD). THE JOHNS HOPKINS UNIVERSITY , Source DAI-B 59/01, p. 258, Jul 1998, 176 pages.
Computer Science
Scientific paper
The Voyager 1 spacecraft flew past Saturn's moon Titan just past the vernal equinox. Visual imagining of the satellite showed it to be completely surrounded by a photochemical haze, with the northern hemisphere much darker and redder than the southern hemisphere. The Voyager Infrared Interferometric Spectrometer (IRIS) measured Titan's upper stratosphere temperatures and found the southern hemisphere to be significantly warmer than the northern hemisphere. IRIS temperature measurements of the surface and tropopause showed little meridional variations. A two-dimensional photochemical transport model was developed for Titan's stratosphere. Transformed Eulerian mean equations were used to determine the meridional circulation. Mechanical forcing was modeled using eddy and Rayleigh friction, while thermal forcing was provided by Newtonian and eddy heating. The model contained 117 photolysis, chemical and condensation reactions for 22 hydrocarbon species along with atomic and molecular hydrogen. The method of conservation of second-order moments was used for the meridional and vertical advection calculations (Prather 1986). The asymmetry in Titan's stratospheric temperatures can be explained by the high thermal inertia in Titan's stratosphere. The phase lag in the stratospheric temperatures from the model radiative equilibrium temperatures reproduces a hemispheric asymmetry similar to the Voyager-measured brightness temperatures. Coustenis and Bezard (1995) analyzed the Voyager IRIS data to calculate hydrocarbon abundances from 53oS to 70oN. They determined that the ethane mixing ratio was approximately constant for all sampled latitudes. In the absence of meridional transport, photochemistry would yield higher concentrations of C2 and C3 hydrocarbon species near the equator than the poles. Meridional advection results in enough tracer transport from low to high latitudes that the latitudinal distributions for ethane, acetylene and propane are much more uniform. The abundance of C2 and C3 hydrocarbons varies 10-15% throughout Titan's seasons. The seasonal variations are greater at higher latitudes and virtually non-existent at the equator. Large seasonal variations for short lived chemical species results in significant seasonal variations in the chemical production rates for organic polymers at middle and high latitudes. These polymers most likely contribute to the seasonal albedo variations.
No associations
LandOfFree
A Two-Dimensional Photochemical Transport Model for the Stratosphere of Titan does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Two-Dimensional Photochemical Transport Model for the Stratosphere of Titan, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Two-Dimensional Photochemical Transport Model for the Stratosphere of Titan will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1271909