title: Storms in the tropics of Titan.
abstract: Methane clouds, lakes and most fluvial features on Saturn's moon Titan have been observed in the moist high latitudes, while the tropics have been nearly devoid of convective clouds and have shown an abundance of wind-carved surface features like dunes. The presence of small-scale channels and dry riverbeds near the equator observed by the Huygens probe at latitudes thought incapable of supporting convection (and thus strong rain) has been suggested to be due to geological seepage or other mechanisms not related to precipitation. Here we report the presence of bright, transient, tropospheric clouds in tropical latitudes. We find that the initial pulse of cloud activity generated planetary waves that instigated cloud activity at other latitudes across Titan that had been cloud-free for at least several years. These observations show that convective pulses at one latitude can trigger short-term convection at other latitudes, even those not generally considered capable of supporting convection, and may also explain the presence of methane-carved rivers and channels near the Huygens landing site.
authors.affiliation: Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA. schaller@ifa.hawaii.edu
authors.forename: E L
authors.initials: EL
authors.lastname: Schaller
authors.forename: H G
authors.initials: HG
authors.lastname: Roe
authors.forename: T
authors.initials: T
authors.lastname: Schneider
authors.forename: M E
authors.initials: ME
authors.lastname: Brown
references.citation: Science. 2005 Oct 21;310(5747):477-9
references.pmid: 16239473
references.citation: Nature. 2007 Jan 4;445(7123):61-4
references.pmid: 17203056
references.citation: Nature. 2005 Dec 8;438(7069):758-64
references.pmid: 16319826
references.citation: Nature. 2006 Jul 27;442(7101):432-5
references.pmid: 16871213
references.citation: Nature. 2006 Jul 27;442(7101):428-31
references.pmid: 16871212
references.citation: Science. 2006 Jan 13;311(5758):201-5
references.pmid: 16410519
references.citation: Science. 2000 Oct 20;290(5491):509-13
references.pmid: 11039930
references.citation: Nature. 2008 Jul 31;454(7204):607-10
references.pmid: 18668101
references.citation: Nature. 1998 Oct 8;395(6702):575-8
references.pmid: 9783583
references.citation: Science. 2005 Oct 21;310(5747):474-7
references.pmid: 16239472
references.citation: Science. 2005 Oct 7;310(5745):92-5
references.pmid: 16210535
references.citation: Proc Natl Acad Sci U S A. 2006 Dec 5;103(49):18421-6
references.pmid: 17121992
references.citation: Nature. 2002 Dec 19-26;420(6917):795-7
references.pmid: 12490943