Abstract. The distribution of particulate matter (dust) in dust devils (DDs), which are well-defined vortexes of wind that range from 1 m to 1,000 m tall, is quantitatively quantified here based on light transmission. We applied the Digital Optical Method (DOM) with digital still cameras to quantify the opacity of the DDs in the Taklimakan Desert, China. This study presents the following unique and important results and interpretations: 1) the distinct horizontal distributions of opacity indirectly proved the existence of DDs’ zone of weak winds in the center of the swirling vortex, similar like the eye of tropical cyclone, which is difficult to be observed directly; 2) The opacity of the DDs decreases with increasing height, however, the dust does appears to settle out, and the relatively calm eye leads to a minimum in dust opacity at the eye; 3) The horizontal distribution of opacity is quasi symmetric with a bimodal across the eye of the DDs; and 4) A new robust method is developed for the representation of three-dimensional structure of opacity based on the observed two-dimensional structures provided by DOM. This research not only proposes a highly reliable, low cost and efficient methodology to characterize the inside structure of DDs, but also provides the information on estimation of dust emissions caused by DDs.
Analysis of the content of dust aerosols in desert regions based on the TOMS aerosol index (AI) as well as solar radiation、dust storm frequency and precipitation was deducted. The AI of desert regions depended not only on dust storms but also on solar radiation. Content of dust aerosols in desert regions were based on the combined effect of sand model and dust devilconvective plume model, and the latter might be more important.
Duststorms can let the 5 spheres correlate closely by the processes of rising,transport and deposition of dust;they are atmosphere,lithosphere,hydrosphere,biosphere and human-sphere.So,duststorm becomes a main tache and a key chain in studying global change and its effects.On the base of simply summarizing dust sources and dust transport characters,we emphatically discussed the influence of duststorms on climate and environment,also reviewed the research advances on of duststorms,such as \!sun umbrella effect\,\!ice core effect and \!iron fertilization effect\.The results show that duststorm,as every natural process,has the double-face characters on the effects on climate,environment and human health and economy.
Based on the 10-years(1995-2004) aerosol simulations of the global aerosol model GEM-AQ/EC,Asian dust aerosol in respect of source and sink distributions and vertical profiles was investigated.Two major dust source regions in East Asia were distributed 1) over the desert areas from southern Mongolia to the middle and west Inner Mongolia;2) the Taklimakan Desert in southern Xinjiang;Dust emissions reached the peak in spring,accounting for 66.81% of the annual dust emissions with the maximum value of 15.29 Mt in April.The Asian dust emissions weaken in summer,level up in autumn and bottom in winter.The significant inter-annual variations and an increasing trend in East Asian dust emissions were experienced over 1995-2004.The high dust depositions were found over East Asian emission areas.Dry dust deposition was a dominant dust removal process over deserts and the surrounding regions,while wet dust deposition was the major process over the long range transport path ways from Northeast China,Southern China,Korea,Japan to West Pacific.Dust deposition had the same seasonal variation to the dust emission and but an increasing trend over the 10 years.The regional dust emissions from East Asian dominated changes of East Asian dust aerosol,the maximum net dust sink areas were concentrated over the immediate downwind regions from the Loess Plateau to the western part of the North China Plain.Taking Asian East region as a whole,East Asian region were the net source of dust aerosol in spring,summer and autumn and but a dust sink in winter,when the strongest westerly jets import dust aerosol from dust sources beyond East Asia into East Asia.Over the most regions of East Asian continent,the vertical profiles of dust aerosols were structured with the high values below 3km in the lower troposphere,while the high dust concentrations were centered around 5km height in the mid-troposphere over the western Pacific and between 6km and 8km in the mid-and upper troposphere north of the desert areas.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)