Lidar has been widely used in remote sensing of atmospheric environment because of its high spatial-temporal resolution and detection sensitivity. As the main noise source in lidar detection, solar background radiation is an important factor to determine target from background. The background noise, which is estimated by taking the average value of the lidar echo signal at a certain height, is usually removed directly. However, the background noise also contains some useful information on the whole layer of the atmosphere. In this paper, atmospheric radiation transmission model software MODTRAN 5.0 was used to simulate the lidar background noise under clear sky condition, combined with micro-pulse lidar (MPL) and meteorological element sounding data. The daytime background noise received by lidar were simulated by standard model method and user-defined model method. The standard model method uses standard atmospheric and aerosol model, which is the common way in traditional background radiation simulation. The user-defined model method uses aerosol and meteorological data measured in Maoming, Guangdong Province in October 2018 to build a user-defined atmospheric model. Results shows that the overall trends of the simulated background radiation from two methods are quite similar to the MPL observation. The user-defined model method can produce more consistent results with the observation than the standard model method, mainly due to that standard model cannot be completely consistent with the real experimental environment. The simulation results in this paper can be used to improve the daytime MPL retrieval, and can also be applied to the retrieving of aerosol particle size information and optical characteristics of cloud in further study.
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