The Post-Equinox Latitudinal Distribution of the Methane Absorption on Saturn in 2011-2012
Abstract
In 2011 and 2012 there were continued perennial spectral observations of Saturn to studying the seasonal spatial and temporal variations of molecular absorption on the disk of the planet. During the last two seasons of observations there were recorded over 3300 CCD-spectra of Saturn's central meridian and zonal spectra by scanning the disk of the planet from the south pole to the north. On the basis of a preliminary sample of this extensive observational material there were prepared the atlases of the band profiles and latitudinal variations of nheir intensity. The general character of the latitudinal variation of the absorption in this period compared to those observed in 2010 remains without especial changes. As in preceding years the ratio of equivalent width W619nm/W725nm at N-temperate latitudes was in 2011 about 27-30 per cent more than at S-temperate latitudes. In the northern hemisphere in 2011 the difference between the CH4 absorption maximum at the latitudes 35-45 N and a minimum at latitudes 55-65 N noticeably increased. In 2012 this maximum of absorption moved southward and the difference decreased. Since this less pronounced difference was observed in previous years also, it is unlikely it can be associated with the effects of the Great Northern Storm, which appeared in December 2010. One feature may be interesting - the central depth of 725 nm band almost does not show this absorption difference in contrast to the depths of weaker absorption bands, whereas its equivalent width shows a latitudinal difference. It may be explained in suggestion that the central absorption in the 725 nm band with residual intensity about 0.25 or less is formed at lower effective optical depth, where the differences in the cloud volume density or the haze altitude are smaller in the range of these latitudes.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #44
- Pub Date:
- October 2012
- Bibcode:
- 2012DPS....4441216T