Aerodynamic properties of agricultural and natural surfaces in northwestern Tarim Basin

• The red date field had the highest u* and z0 while the desert had the lowest u* and z0.
• Stubble biomass on the surface prior to sowing affected u* and z0 in cotton field.
• Aerodynamic roughness changed slightly over time at the desert site.
• Desert has the greatest potential for wind erosion compared to crop land.

Friction velocity (u*) and aerodynamic roughness (z0) are atmospheric parameters that influence the flux of windblown dust. These parameters have not been quantified for different land use types in the Tarim Basin of China, one of the largest sources of atmospheric dust in the world. Wind speed profiles were measured and used to determine d, u* and z0 of a cotton (Gossypium hirsutum L.) field, red date (Ziziphus jujuba L.) orchard and native desert during the spring wind erosion season of 2012 and 2013. In addition, d, u* and z0 were estimated using Raupach's model. During periods of high winds sufficient to cause erosion in spring, d averaged 0.28, 0.067 and 0 m; u* averaged 0.39, 0.51 and 0.35 m s−1; and z0 averaged 7.0, 17.0 and 1.2 mm for respectively the cotton field, red date orchard and desert. Estimates of d, u* and z0 according to Raupach's model during the same periods of high winds were 0.10, 0.16 and 0 m; 0.56, 0.73 and 0.49 m s−1; and 12.6, 21.9 and 1.8 mm for respectively the cotton field, red date orchard and desert. The Raupach model, which depends on canopy height and area index, overestimated u* and z0 for the three land use types during most high wind events. The desert had the greatest potential for flux of windblown dust (due to the lowest z0) while the red date orchard has the lowest potential for dust flux (due to the highest z0).