| Dust aerosol, namely mineral dust, is a kind of mineral aerosol form, the main composition of atmospheric aerosol and mainly comes from arid and semi-arid desert region. Atmospheric visibility has been affected by the dust aerosols, which worsen air quality, and bring too much harm to the health of humans and animals. Dust aerosol, however, is one of the most important factor of climate change, through the "umbrella effect","iron fertilizer effect" and "ice nucleation effect" linking layers of the earth (hydrosphere, atmosphere, lithosphere, biosphere and human) together, through the direct and indirect radiation effect and participating in the process of cloud precipitation, has become the key link in the process of material circulation and global climate change. Researches about dust aerosol are focused mainly on sand dust weather disasters such as the dust storm, not only because which has the characteristics of long-distance transmission, however, at present the latest research indicates that only dust storm process is unable to explain the change of atmospheric dust aerosol content over the desert regions in no dust weather process. Therefore, dust devil movements caused by solar radiation may be a source of atmospheric dust aerosols over the desert in no dust weather process. Some studies take solar radiation change to replace the dust devil heat convection, reflecting the dust devil’s contribution to the dust aerosol by indirect method, and have achieved some primary results. Because the field observations of dust devil have a lot of difficulties, this article researches the dust devil thermal dynamic theory-thermodynamic efficiency, trying to establish its relationship with the solar radiation.In addition, this paper calculated the average annual contribution amount of dust aerosols about dust devils and dust storms,compares the quantitative relation, and has the potential to update the knowledge and understanding about the source of atmospheric dust aerosols and dust aerosol change.This article using the taklimakan desert and gobi desert area on the convective boundary layer and the surface temperature field test data, calculates the thermodynamic efficiency of the dust devil, and combining both solar radiation intensity at the same time, discusses the source of dust aerosols in the northwest of China, the research results as follows:(1) In desert and gobi area under the condition of no wind, dust devil has obvious diurnal and monthly variation, the dust aerosols of the two areas may mainly come from dust devils caused by heat convection.(2) The thermodynamic efficiency of dust devil and the diurnal, monthly features of dust devil occurring have a good consistency, which indicates that the thermodynamic efficiency from calculation can generally reflect the dust devil changes in nature.(3) Dust devil’s contribution to the dust aerosols has obvious seasonal variation:the summer maximum, the Spring Festival second, autumn and winter are smaller, and the desert region is greater than the gobi region.(4) The thermodynamic efficiency, dust amount by dust devil and dust aerosol index in no dust weather have a significant positive relationship, showing that dust devils are better to reflect the characteristics of atmospheric aerosols than dust storms.(5) By reviewing dust amount from dust storms and dust devils in Chinese desert and gobi regions, the results show that dust devil is equal with or more important than dust storm in contribution to dust aerosols. |
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