Paleoclimate of Titan with hydrocarbon oceans and continents simulated by a global climate model

Abstract

Titan’s paleoclimate in the presence of hypothetical hydrocarbon oceans 1 Gyr ago is simulated by a global climate model with a slab ocean model. Simulations are run for two different ocean compositions and with and without continents. The climate over ethane-rich oceans is dry with respect to methane but is windier than over methane-rich oceans. Continents do not substantially change the climate if the ocean is ethane-rich but continents are somewhat windier than the oceans for orographic reasons. The climate over methane-rich oceans is very moist but calm as long as there are no continents. Global imbalance between the N2 release from the ocean in spring and N2 absorption by the ocean in autumn due to the temperature dependence of the N2 solubility in the ocean causes a semi-annual variation in global-mean surface pressure by ∼0.1 hPa. Continents surrounded by methane-rich oceans induce a sea breeze circulation in summer due to a sea-land temperature contrast. The sea breeze causes intense orographic precipitation on windward slopes of continents. Possible presence of circum-Xanadu continents surrounded by methane-rich oceans may have been conducive to the formation of the observed numerous fluvial networks in Xanadu.