Abstract. Using the MODIS satellite data and station atmospheric turbulence observation data in Nagqu area of northern Tibetan plateau in 2008, 2010 and 2012, with the Massman retrieved model and an independent method to determine aerodynamic surface roughness, the temporal and spatial variation characteristics of the surface roughness was analyzed. The results show that the surface roughness has obvious seasonal variation characteristics. From February to August, Z0m increases constantly with the ablation of snow and vegetation growth, and the maximum value reaches 4–5 cm at BJ site. From September to February, Z0m gradually decreased because of the post-monsoon over the plateau, and the values decreased to about 1–2 cm. The snowfall in abnormal years is the main reason why Z0m is obviously lower than that in normal. The underlying surface can be divided into four categories according to the different values of Z0m: snow and ice, sparse grassland, lush grassland and town. Among them, lush grassland and sparse grassland account for 62.49 % and 33.74 % respectively in the region, which are the main categories, and their Z0m annual changes are between 2–6 cm and 1–4 cm. The correlation between the two methods are positively related to each other, and the retrieved data are smaller than the measured results due to the average sliding action. On the whole, Z0m calculated by satellite data retrieved algorithm is feasible, it can be applied to improve the model parameters of land surface model parameters and the accuracy of model simulation, better reveal the heat flux exchange.
Spatio-Temporal Variation of Reference Evapotranspiration and Its Climatic Drivers over the Tibetan Plateau during 1970–2018