OH radicals are important oxidants in the atmosphere, and play important roles in the formation and the conversion of other gases and aerosols in the atmosphere. This paper reviews the research progresses of OH radicals at home and abroad. The temporal and spatial distributions and the changes of the upper stratospheric and mesospheric OH radicals are analyzed based on the MLS (microwave limb sounder) satellite data,especially, the vertical distributions of OH radicals over China. It is shown that there are obvious seasonal and diurnal changes of the OH radical volume mixing ratio in the upper stratosphere and the mesosphere. Compared the OH radical volume mixing ratio over China with the zonal mean values of the same latitudes, it is found that the most of the observed volume mixture ratios of the day and the night are similar at the same latitudes, and there is no obvious difference between them. The profiles over some areas of China reflect the detailed vertical distributions of the day and the night. In a word, the diurnal and seasonal variations of the OH radical concentration in the middle atmosphere can obviously seen. The OH radical volume mixture ratio is also affected by the solar activity, and the annual variation is not significant.

THz limb detecting  /  middle atmosphere  /  OH radicals  /  temporal and spatial distribution