关键词: 月基对地观测, 热红外, 微波, 电离层, 能量衰减, 折射率

Abstract: Moon-based Earth observation is a new space observation method，which conducts continuous and long-term observations of the Earth through the Moon platform.It has unique disadvantages such as large viewing angle，high width，multi-angle imaging，high time resolution，and long design life.The ionosphere is located in the high-altitude area up to 1000km above the Earth's surface，and it is an important factor affecting the quality of Moon-based Earth observation imaging.To explore the thermal infrared and microwave radiation characteristic for Moon-based Earth observation，the ionosphere influence on microwave imaging for Moon-based Earth observation platform was analyzed，and the attenuation value in microwave radiation brightness temperature under different latitude areas was simulated.First，the ionospheric electron concentration and the refractive index change law were estimated based on the Chapman distribution.Then the attenuation for different heights as well as transmission paths during ionosphere passing through were calculated，which used the observed zenith angle，collision frequency，etc.Finally，the integration method was adopted to obtain the thermal infrared and microwave energy attenuation in the ionosphere.Results show that the thermal infrared and microwave energy attenuation in the ionosphere of Moon-based Earth observation platform depends on the collision frequency，band，and viewing zenith angle.The ionosphere has greater effect on thermal infrared imaging than microwave imaging for Moon-based Earth observation.In addition，the Moon-based microwave brightness temperature value in the low latitude regions is greatly affected by the ionosphere attenuation with a decrease of about 1.304K，followed by the mid-latitude regions.

Key words: Moon-based Earth observation, thermal infrared, microwave, ionosphere, energy attenuation, refractive index