J/ApJ/724/L84ivo://CDS.VizieR/J/ApJ/724/L84doi:10.26093/cds/vizier.17249084CDSTeanby N.A.Irwin P.G.J.de Kok R.Nixon C.A.2012-09-08T07:03:15Z2012-08-20T11:39:38ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsolar-system-planetsinfrared-astronomyspectroscopyWe use a six-year data set (2004-2010) of mid-infrared spectra measured by Cassini's Composite InfraRed Spectrometer to search for seasonal variations in Titan's atmospheric temperature and composition. During most of Cassini's mission Titan's northern hemisphere has been in winter, with an intense stratospheric polar vortex highly enriched in trace gases, and a single south-to-north circulation cell. Following northern spring equinox in mid-2009, dramatic changes in atmospheric temperature and composition were expected, but until now the temporal coverage of polar latitudes has been too sparse to discern trends. Here, we show that during equinox and post-equinox periods, abundances of trace gases at both poles have begun to increase. We propose that increases in north polar trace gases are due to a seasonal reduction in gas depletion by horizontal mixing across the vortex boundary. A simultaneous south polar abundance increase suggests that Titan is now entering, or is about to enter, a transitional circulation regime with two branches, rather than the single branch circulation pattern previously observed.2010ApJ...724L..84Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/724/L84CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJS/191/96 : IR spectra and optical constants of ices (Moore+, 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/724/L84https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/724/L84http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/724/L84https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/724/L84https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/724/L84http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/724/L84GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/ApJ/724/L84/table1Average temperature and composition derived from 104 individual observation sequencesLatLatitudedegpos.bodyrc.latintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintParameterTemperature or gas abundance (1)meta.notechar2004.75? Average Value between 2004.50 and 2005.00stat.valuedoublenullable2005.38? Average Value between 2005.00 and 2005.75stat.valuedoublenullable2006.12? Average Value between 2005.75 and 2006.50stat.valuedoublenullable2007.00Average Value between 2006.50 and 2007.50stat.valuedouble2008.00Average Value between 2007.50 and 2008.50stat.valuedouble2008.75Average Value between 2008.50 and 2009.00stat.valuedouble2009.30Average Value between 2009.00 and 2009.60stat.valuedouble2010.10? Average Value between 2009.60 and 2010.60stat.valuedoublenullable