The Influence Of Surface Temperature Structure On Mantle Convection Evolution

In the process of planetary evolution,the surface temperature of a planet not only changes with time,but also shows obvious spatial distribution characteristics due to factors such as planetary curvature,light path and albedo of the planetary surface.This study mainly explores the impact of the spatial distribution of planetary surface temperature on the dynamic processes inside the planet.Based on three-dimensional numerical models,the convection process inside the mantle is simulated,and the surface temperature of the planet is approximated by a sine function of colatitude.We discuss the influence of the spatial distribution of surface temperature on a series of different mantle convection models.The convection models shown in this study can be roughly divided into two types,namely high-order mantle convection models and low-order mantle convection models.For these two different mantle convection models,the spatial distribution of surface temperature has a significant impact on their internal convection processes,but there are certain differences in the impact of surface temperature on them.On the one hand,for high-order mantle convection models,the most significant impact of the spatial distribution of surface temperature is to change the position of upwellings and downwellings in the models,making the upwellings in the models more likely to gather in the equatorial region,while the downwellings in the models are more likely to gather in the poles.And accompanied by the aggregation of upwellings and downwellings,the models also changes from the original high-order convection mode to a second-order convection mode.On the other hand,it is found that low-order convection modes are produced in models with low Rayleigh number or low viscosity layer,but there are differences between them.The first-order convection mode produced by the low viscosity layer model is very stable.In this model,even if a large spatial difference distribution of surface temperature is considered,it will not destroy its original convection mode.The spatial distribution of surface temperature only changes the position of upwellings and downwellings in the model,making both move towards the equator.However,the low Rayleigh number model will produce an unstable first-order convection mode.Adding a spatial distribution of temperature on the surface of this model will destroy its original first-order convection mode and make it change to a second-order convection mode.At the same time,the spatial distribution of surface temperature also affects the position of upwellings and downwellings in the model.In addition,based on numerical simulation results of stable first-order convection,we believe that spatial distribution of surface temperature is one of the possible reasons affecting the paleolatitude of the supercontinent.