Recent years have seen a marked revival of interest in aeolian geomorphology, both on Earth (e.g. McKee 1979, Nickling 1986, Brookfield & Ahlbrandt 1983) and on the planets (Greeley & Iversen 1985). To evaluate the role of wind as a geomorphological agent, a knowledge of wind structure on both the synoptic and micro-meteorological scales is necessary