title: Semi-annual oscillations in Saturn's low-latitude stratospheric temperatures.
abstract: Observations of oscillations of temperature and wind in planetary atmospheres provide a means of generalizing models for atmospheric dynamics in a diverse set of planets in the Solar System and elsewhere. An equatorial oscillation similar to one in the Earth's atmosphere has been discovered in Jupiter. Here we report the existence of similar oscillations in Saturn's atmosphere, from an analysis of over two decades of spatially resolved observations of its 7.8-microm methane and 12.2-microm ethane stratospheric emissions, where we compare zonal-mean stratospheric brightness temperatures at planetographic latitudes of 3.6 degrees and 15.5 degrees in both the northern and the southern hemispheres. These results support the interpretation of vertical and meridional variability of temperatures in Saturn's stratosphere as a manifestation of a wave phenomenon similar to that on the Earth and in Jupiter. The period of this oscillation is 14.8 +/- 1.2 terrestrial years, roughly half of Saturn's year, suggesting the influence of seasonal forcing, as is the case with the Earth's semi-annual oscillation.
authors.affiliation: MS 169-237, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA. glenn.orton@jpl.nasa.gov
authors.forename: Glenn S
authors.initials: GS
authors.lastname: Orton
authors.forename: Padma A
authors.initials: PA
authors.lastname: Yanamandra-Fisher
authors.forename: Brendan M
authors.initials: BM
authors.lastname: Fisher
authors.forename: A James
authors.initials: AJ
authors.lastname: Friedson
authors.forename: Paul D
authors.initials: PD
authors.lastname: Parrish
authors.forename: Jesse F
authors.initials: JF
authors.lastname: Nelson
authors.forename: Amber Swenson
authors.initials: AS
authors.lastname: Bauermeister
authors.forename: Leigh
authors.initials: L
authors.lastname: Fletcher
authors.forename: Daniel Y
authors.initials: DY
authors.lastname: Gezari
authors.forename: Frank
authors.initials: F
authors.lastname: Varosi
authors.forename: Alan T
authors.initials: AT
authors.lastname: Tokunaga
authors.forename: John
authors.initials: J
authors.lastname: Caldwell
authors.forename: Kevin H
authors.initials: KH
authors.lastname: Baines
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Hora
authors.forename: Michael E
authors.initials: ME
authors.lastname: Ressler
authors.forename: Takuya
authors.initials: T
authors.lastname: Fujiyoshi
authors.forename: Tetsuharu
authors.initials: T
authors.lastname: Fuse
authors.forename: Hagop
authors.initials: H
authors.lastname: Hagopian
authors.forename: Terry Z
authors.initials: TZ
authors.lastname: Martin
authors.forename: Jay T
authors.initials: JT
authors.lastname: Bergstralh
authors.forename: Carly
authors.initials: C
authors.lastname: Howett
authors.forename: William F
authors.initials: WF
authors.lastname: Hoffmann
authors.forename: Lynne K
authors.initials: LK
authors.lastname: Deutsch
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Van Cleve
authors.forename: Eldar
authors.initials: E
authors.lastname: Noe
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Adams
authors.forename: Marc
authors.initials: M
authors.lastname: Kassis
authors.forename: Eric
authors.initials: E
authors.lastname: Tollestrup