Feng JianWu ， Liu HuiZhi ， Wang Lei ， Du Qun ， Shi LiQing
2012-02-01 SCIENCE CHINA-EARTH SCIENCES 2012 55(卷), 2(期), (254-261页)
Here we report a multiyear study on the surface roughness length and bulk transfer coefficients over the degraded grassland and cropland surfaces in a semiarid area of China. Eddy covariance measurement and the meteorological profile observation data were used to analyze characteristics of these parameters on the diurnal, seasonal, and annual scales. Significant seasonal and annual variations of the aerodynamic roughness length are observed over the two surfaces. A large variation of kB (-1) is measured during the day. Both kB (-1) and the bulk transfer coefficients exhibit significant seasonal and annual variations. During the growing season (May to October), average C (d) and C (h) are 3.1x10(-3) and 2.5x10(-3) over the degrade grassland surface, and 4.7x10(-3) and 3.1x10(-3) over the cropland surface respectively. During the non-growing season, average C (d) and C (h) are 2.3x10(-3) and 2.0x10(-3) over the degrade grassland surface, and 2.9x10(-3) and 2.2x10(-3) over the cropland surface respectively.