Near-surface wind environment in the Yarlung Zangbo River basin, southern Tibetan Plateau

Abstract

Aeolian processes have been studied extensively at low elevations, but have been relatively little studied at high elevations. Aeolian sediments are widely distributed in the Yarlung Zangbo River basin, southern Tibetan Plateau, which is characterized by low pressure and low temperature. Here, we comprehensively analyzed the wind regime using data since 1980 from 11 meteorological stations in the study area, and examined the interaction between the near-surface wind and aeolian environment. The wind environment exhibited significant spatial and temporal variation, and mean wind speed has generally decreased on both annual and seasonal bases since 1980, at an average of 0.181 m/(s•10a). This decrease resulted from the reduced contribution of maximum wind speed, and depended strongly on variations of the frequency of sand-driving winds. The drift potential and related parameters also showed obvious spatial and temporal variation, with similar driving forces for the wind environment. The strength of the wind regime affected the formation and development of the aeolian geomorphological pattern, but with variation caused by local topography and sediment sources. The drift potential and resultant drift direction were two key parameters, as they quantify the dynamic conditions and depositional orientation of the aeolian sediments. Wind affected the spatial variation in sediment grain size, but the source material and complex topographic effects on the near-surface wind were the underlying causes for the grain size distribution of aeolian sands. These results will support efforts to control aeolian desertification in the basin and improve our understanding of aeolian processes in high-elevation environments.

Provenance, source weathering, and tectonics of the Yarlung Zangbo River overbank sediments in Tibetan Plateau, China, using major, trace, and rare earth elements

“…These features indicate low-moderate weathering, which are consistent with the results from Yang et al (2020).…”

Variation of the winter mid-latitude Westerlies in the Northern Hemisphere during the Holocene revealed by aeolian deposits in the southern Tibetan Plateau

“…1). Aeolian deposits are mainly distributed in the wide river valley at an average altitude of nearly 4000 m, including the Maquanhe wide valley, Shigatse wide valley, Shannan wide valley, and Mainling wide valley, from west to east, lying mainly within the area of 29.25–29.75°N and 88–92°E (Ling et al, 2019; Yang et al, 2020a). There is almost no aeolian accumulation in the narrow valleys due to the lack of sediment supply and the strong winds.…”

“…The mean annual temperature in this region ranges from 1.5–8.8°C, and the mean annual precipitation ranges from 131.6–676.7 mm (Shen et al, 2012). Aeolian activity occurs mainly in the winter and spring, and the mean annual near-surface wind speed ranges from 1.6–3.3 m/s (Yang et al, 2020b).

Figure 1.(color online) Location of the study area and the studied aeolian sedimentary sequence.

…”

Spatial and Temporal Variation of the Near-Surface Wind Environment in the Sahara Desert, North Africa

“…It is also worth noting that the mean wind speed reduced from 1980 to 2000, following which it showed a fluctuating increasing trend (Figure 2). Previous studies have shown that wind speeds decreased in most regions of the world before 2000, although at different rates of decline (Vautard et al, 2010;Wu et al, 2018;Yang et al, 2020). The decreasing trend in wind speed can be generally attributed to variations in the atmospheric temperature, precipitation, dust volume (Mcvicar and Roderick, 2010), surface vegetation coverage and land-use changes (Cui et al, 2018), surface roughness and the effects of human activities (Kim and Paik, 2015;Yang et al, 2020).…”

“…Previous studies have shown that wind speeds decreased in most regions of the world before 2000, although at different rates of decline (Vautard et al, 2010;Wu et al, 2018;Yang et al, 2020). The decreasing trend in wind speed can be generally attributed to variations in the atmospheric temperature, precipitation, dust volume (Mcvicar and Roderick, 2010), surface vegetation coverage and land-use changes (Cui et al, 2018), surface roughness and the effects of human activities (Kim and Paik, 2015;Yang et al, 2020). The rate of decrease in mean wind speed observed in the current study is consistent with the value (0.08 m s −1 10a −1 ) reported by Wu et al (2018) for East Asia, South Asia and Europe.…”