The effects of polar rain electron precipitation on the low-energy ion escape in the polar region

Principal Investigator: Dr. Li Kun

Period：2023-2025

Project Description:

The Earth’s atmosphere has been losing materials into space since its formation and during its evolution. This is believed to be one of the reasons why the composition of the atmosphere keeps changing. At present, the atmospheric escape takes place mainly in the topside ionosphere, where the neutral particles are ionized. With the influences of the ambient electric and magnetic fields, ions are accelerated to be fast than the escape velocity, allowing them to enter the space. In the polar regions, the escaping particles are dominated by low-energy ions. It is known that the low-energy ions gain enough energies to escape from the solar irradiation and the solar wind electromagnetic energy, which dissipate in the polar region. However, the effects of an additional type of energy that carried by the polar rain electron precipitation along the open field lines from the solar wind has been rarely studied. On the contrary, these electron precipitations may diminish the ambipolar electric field that enables the ion outflow. Whether the electron precipitation increase or decrease the ion outflow is still unknown. In order to answer this question, we use data from DMSP and Cluster satellites. We develop an algorithm to automatically recognize the polar rain cases and establish the data set. We analyze the correlation between polar rain and the low-energy ion outflow. Our results will provide us clues on understanding the evolution of the Earth’s atmosphere and its habitability.