Turbulent airflow is a fundamental factor that controls the geomorphology of sand dune systems, especially dune expansion and sandy desertification. However, little is known about turbulent air flow in dune systems, and this limits efforts to control dune expansion and sandy desertification. To obtain some of the missing information, we calculated the turbulent airflow characteristics over a transverse dune in the Tengger Desert in southeastern China. We found that the angle of airflow at the dune crest controls flow angles at middle of the dune's stoss slope and at the toe of the leeward slope, and also controls the turbulent flow characteristics over the dune surface. The critical wind direction was from the NW (wind directions ranged from 355° to 45° to the crest perpendicular line [CPL]) and SE (wind directions ranged from 65° to 165° with respect to the CPL), and about 20° and25° with respect to the CPL for northwesterly winds and southeasterly winds, respectively. The kinematic Reynolds' stress (RS_k), streamwise turbulence intensity (CV_u), and total kinetic energy (TKE) were largest close to the critical wind direction for winds from the NW, indicating that dune movement was mainly controlled by the critical wind direction. However, TKE, RS_k, and CV_u differed between southeast and northwest winds; for southeasterly winds, they were largest for wind directions from 65° to 115° with respect to the CPL and similar to the values for wind directions from 115° to 165° with respect to the CPL, indicating asymmetrical sand movement. We conclude that, for closely spaced transverse dunes, sand transport is controlled by the critical wind directions; this indicates that efficient control of sand movement and sandy desertification will benefit from sand-control structures that block airflow from the critical wind directions.