Planetary temperature calculations under Milankovitch cycles

UDC 551.511.13

Planetary temperature calculations under Milankovitch cycles

Abdusamatov H. I., Lapovok Yevgeniy V., Khankov S.I.

A model for variation with time of the Earth’s planetary temperature while the Earth is moving around the Sun along elliptical trajectory is presented. The model includes an equation for non-stationary heat balance of the Earth; analytical dependence of the solar constant on the distance between the Earth and the Sun; as well as analytical description for variation with time of a distance from the Erath to the Sun depending on the eccentricity of the Earth’s orbit and Earth's rotation period around the Sun. The calculation shows that as the Earth is moving close to aphelion most of the time the insolation of the Erath’s surface decreases when its orbit eccentricity increases. The Earth’s planetary temperature is shown not to change significantly during the year while The Earth is moving from perihelion to aphelion, and the average temperature is shown to decrease by 1.5 K as a maximum if Bond’s albedo of the Earth remains constant. A significant decrease of planetary temperature and an ice age might be possible only if ice-albedo positive feedback takes place when Bond’s albedo increases due to an increase of ice and snow cover of the Earth’s surface. The dynamic of planetary temperature change was calculated assumed that the active layer of the ocean remained constant i.e. 700 m. The selection of active layer depth influences transient thermal processes only and does not influence an average planetary temperature.

Keywords: Milankovitch cycles, planetary temperature of the Earth, elliptic orbit, eccentricity, solar constant, Bond’s albedo.

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