Contributions of gust under stationery weather conditions to the dust aerosol budget in northwestern China

Abstract

Dust aerosols play an important role in climate change, however, the annual emissions simulated from dusty weather and dust devils are largely underestimated than observed, possibly due to the lack of gust on dust emission contribution under stationary weather conditions. This study estimates the gust emission by the use of 1-year measurements of 10-min wind speed from two field sites in Dunhuang (sandy desert) and Yumen (gravel desert) in northwestern China, and the concurrent estimations of dusty weather and dust devils are examined as well. The results show that: 1) about 25% of gust could contribute to dust emission throughout the year regardless in Dunhuang or Yumen. 2) Three dust processes have diverse occurrence times and intensities, i.e. gust could occur at any time with fiercer fluctuation in dust emission than dust devils and dusty weather which mainly occur between April and September and in spring, respectively. 3) During the non-dusty seasons, both dust devils and gust are prominent with gust overwhelmingly contributing the most, while during the dusty season when three mechanisms co-exists, dusty weather outperforms the others in Dunhuang, but takes a relatively even share of around 33% as the other two in Yumen. 4) On an annual scale, gust is the highest and second-highest contributor to the annual total dust emissions in Yumen and Dunhuang, respectively. This study not only highlights the nonnegligible contributor/mechanism of gust to dust emission, complementing the existing emission mechanisms to form a complete dust emission mechanism system, but also sheds light on a new perspective explaining the largely underestimated dust aerosols that are significant in the assessment of climate effects.