Contrasting responses to orbital precession on Titan and Earth
Earth and Titan exhibit contrasting atmospheric responses to orbital precession. On Earth, most (water) precipitation falls in low latitudes, and precipitation is enhanced in a hemisphere when perihelion occurs in that hemisphere's summer. On Titan, most (methane) precipitation falls in high latitudes, and precipitation is enhanced in a hemisphere when aphelion occurs in that hemisphere's summer. We use a Titan general circulation model to elucidate the dynamical reasons for these different responses to orbital precession. They arise primarily because of the different diurnal rotation rates of Titan and Earth. The slower rotation rate of Titan leads to wider Hadley cells that transport moisture into polar regions. Changes in the length of summer, rather than in the intensity of summer insolation as in Earth's tropics, then dominate the precession response of the hydrologic cycle.
© 2016 American Geophysical Union. Accepted manuscript online: 19 July 2016; Manuscript Revised: 15 July 2016; Manuscript Accepted: 15 July 2016; Manuscript Received: 8 April 2016. This work was supported by the NASA Outer Planets Research Program (Grant NNX10AQ05G) and by the National Science Foundation (Grant AGS-1049201). The program code for the Titan GCM is available at climate-dynamics.org. Simulation output is available from the authors upon request.
Erratum In the originally published version of this article, several instances of text were incorrectly typeset. The following have been since been corrected, and this version may be considered the authoritative version of recordIn Figures 1 and 2, the degree symbol has been removed after "Latitude" and has been correctly added to the latitude labels (-60, -30, 0, 30, and 60).
Published - Liu_et_al-2016-Geophysical_Research_Letters.pdf
Supplemental Material - grl54748-sup-0001-s01AA.pdf