The observation of metastable helium He(23S) by ground-based resonant lidar has been gradually developing. For example, a corresponding lidar has been built in Danzhou, China, and has been observed for several months. More observations may be conducted in the future. So the paper will analyze the advantages and disadvantages of observations at different locations on Earth from the perspective of He(23S) density, mainly using previously generation models of He(23S) density and empirical models of energetic electron (>19.8eV) flux in polar regions. The results show that compared to passive observation conjugate photoelectrons have a significant impact on the observable duration of middle-low latitudes, and the precipitation electrons in polar regions are the main source of He(23S) generation during most nights.
Liu et al. (2026) studied this question.