The Sahara Desert is the largest source of dust on Earth, and has a significant impact on global atmospheric changes. Wind is the main dynamic factor controlling the transport and intensity of dust in the Sahara Desert. This study comprehensively analyzed the spatial and temporal variation in the wind regime of the Sahara Desert from 1980 to 2019 using data from 17 meteorological stations to improve awareness of global atmospheric changes and the intensity of regional aeolian activities. All wind speed parameters decreased from northwest to southeast. While there were significant differences in the trends of temporal variation in wind speed among the different regions, there was an overall decreasing trend across the Sahara Desert, with an average wind speed of 0.09 m s−1 10 a−1. This decrease was closely related to wind frequency. The easterly, westerly, and northerly winds dominated, with more complex wind direction in the northern region. Seasonal differences in wind direction were observed in all regions. The wind direction frequency of wind speeds >6 m s−1 exceeded those with wind speeds <6 m s−1 in the western and northern regions, whereas other regions showed an opposite pattern. The highest drift potential (DP) and resultant drift potential (RDP) were found in the western and northern regions, and during spring and winter. There was a trend of decreasing annual variation in DP and RDP in all regions. The directional variability (RDP/DP) indicated mostly intermediate and high variability in wind direction. Resultant drift direction (RDD) indicated that a mainly southwest wind direction. No apparent trends in temporal variation in RDD and RDP/DP were observed. Total DP was strongly influenced by DP and the magnitude and frequency of strong winds in the prevailing wind direction. No strong correlation between wind regimes and dune types was observed in this desert, indicating the complexity of factors affecting dune morphology.

Dunes composed of granular materials are present in deserts and other environments, such as subaqueous environments and environments on other planets, with very different time and length scales for their evolution. In arid regions, barchans (transverse dunes) develop under a unimodal wind regime, and are oriented perpendicular to the sand transport direction, whereas linear (longitudinal) dunes develop under a bimodal wind regime and are oriented parallel to the sand transport direction. However, field survey results cannot be explained solely by the wind because barchans and linear dunes can coexist under the same wind regime. Here, we investigated China’s Qaidam Basin, where barchans and linear dunes coexist. We measured dune morphology, analyzed wind data, and quantified the sand supply (equivalent sand thickness) to describe their development environment, and focused on the effect of sand supply to explore the combined effects of wind regime and sand supply on the coexistence of barchans and linear dunes. In our study area, barchans and linear dunes had low heights. The wind regime was narrowly bimodal, with low directional variability. The sand supply was limited (low equivalent sand thickness), but was greater for barchan chains than for barchans, and linear dunes had the smallest supply; the equivalent sand thickness in the linear dune areas was half that in barchan areas and one-quarter that in barchan chain areas. Except in the presence of topographical barriers and cohesive sediments, a unimodal or bimodal wind regime with an acute angle allows barchans and linear dunes to coexist under a low sand supply. The linear dunes and the barchans migrated along the resultant drift direction. Though we studied aeolian dunes, these findings will increase our understanding of these similar bedforms that develop in other planetary environments (e.g., Mars).