Observational study of the vertical wind profile in the Inner Mongolia grassland near-surface

Using the 100 m tower atmospheric turbulence observation experiment data during 2009-2010 in Inner Mongolia offered by the National Climate Center, the variation characteristics of vertical profile of wind speed under the different stability conditions are analysed, and the wind profile expression is established based on the local similarity theory. The results show that: (1) In the Inner Mongolia grassland near surface atmosphere, the probability of unstable stratification and stable stratification occurs much higher than the neutral and weakly unstable and weakly stable stratification. (2) Under stable stratification, the characteristics of the atmosphere change obviously in the vertical direction, which means that the hierarchical consideration is needed. According to the atmospheric turbulence observation experiment data, under stable stratification, the relationship between the dimensionless velocity gradient and the stability ζ can be expressed as 1+βmζ, in which βm changes with the height: βm takes 4.3-5.4 under 30 m height; βm takes 2.9-3.4 between 30-50 m; and βm takes 2.0-2.9 over 50 m.