Numerical simulation of atmospheric general circulation under different obliquity of Earth

Abstract

By using the second version of the Community Atmosphere Model (CAM2) of NCAR, the general circulations of the Earth's atmosphere were simulated under different obliquity condition. The results imply that three-cell circulation turn weak when the obliquity turn large except that the three-cell circulation in Northern Hemisphere in winter, Hadley circulation in Southern Hemisphere in spring and Hadley circulation in Southern Hemisphere in summer turn strong with the obliquity turns large. For annual mean three-cell circulation, its intensity turns weak with the obliquity turn large. The extension of Hadley circulation in Southern Hemisphere turn large when the obliquity turns large, while the extension of Hadley circulation in Northern Hemisphere and Ferrel circulation in Southern Hemisphere turn small with the obliquity turns large. The ascending branch of Hadley circulation in the Southern Hemisphere turn strong significantly under the 60° obliquity condition then normal obliquity of Earth. Furthermore, for annual mean the extension and the velocity of easterly wind in stratosphere over the equator turn large when the obliquity turns large. While the extension of the westerly wind turn small with the obliquity turns large. With the obliquity turns large, the strength of jet stream in Northern Hemisphere turn weak, the strength of jet stream in Southern Hemisphere turn strong. The same characteristics for the four seasons are that with the obliquity turns large, the easterly in the troposphere and westerly in the Northern Hemisphere turn weak, the strength of jet stream at mid-latitude in Northern Hemisphere turn weak. The difference are that with the obliquity turns large, the strength of jet stream at mid-latitude in Southern Hemisphere in spring turn strong, the westerly wind at middle and high latitude have opposite change trends in summer and autumn in Southern Hemisphere, the global westerly wind in winter turn weak.