Advances in our knowledge of the aeolian processes governing sand dune dynamics have been restricted by a reliance on measures of time-averaged airflow, such as shear velocity (u+ó-ü+¢). It has become clear that such measures are incapable of explaining the complete dynamics of sediment transport across dune surfaces. Past evidence from wind tunnel and modelling studies has suggested that in some regions on a dune's surface the sediment transport might be better explained through investigations of the turbulent nature of the airflow. However, to date there have been no field studies providing data on the turbulent characteristics of the airflow around dunes with which to support or refute such hypotheses. The field investigation presented here provides mean and turbulent airflow measurements across the centre-line of a barchan sand dune in Namibia. Data were collected using arrays of sonic anemometers and were compared with sand flux data measured using wedge-shaped traps. Keywords: Turbulence, Sand dune, Shear velocity, Reynolds stress, Sediment transport.