Dust concentrations and particle-size characteristics of an intense dust haze event: Inland Delta Region, Mali, West Africa
Dust concentrations and particle-size characteristics of an intense dust haze event: Inland Delta Region, Mali, West Africa
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DOI：
10.1016/1352-2310(95)00432-7
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发表时间：
1996-04
影响因子：
5
通讯作者：
J. Gillies;W. Nickling;G. McTainsh
中科院分区：
文献类型：
--
作者：
J. Gillies;W. Nickling;G. McTainsh
1990 年 4 月 27 日至 30 日期间，在马里内陆三角洲地区监测到了强烈的尘埃羽流。该羽流是由距研究地点 500 公里处的雷电下沉气流产生的，随后由低速风携带，在产生后约 28 小时到达。事件期间和极低风切变条件下测得的大气粉尘峰值浓度（13,735 ug m-s）超过了文献中先前报道的任何尘霾事件。羽状尘埃的粒径特征表明其来源较远。粉尘粒径分布呈单峰分布，10 m 处的平均值为 3 μm。计算的垂直灰尘通量表明，在羽流到达时，颗粒的垂直通量与当地风切变不平衡。这是大气中灰尘质量浓度非常高的结果。在浓度峰值水平过去后，垂直灰尘通量与风切变速度之间的关系趋向于预测灰尘在大气中向上移动的关系，随风切变速度的四次方变化。
An Intense dust plume was monitored in the Inland Delta region of Mali during the period 27–30 April 1990. The plume was generated by thunder cell downdraughts 500 km from the study site and subsequently carried by low-velocity winds to arrive approximately 28 h after its generation. Peak atmospheric dust concentrations (13,735 ug m- s) measured during the event and under very low wind shear conditions exceeded any previously reported in the literature for dust haze events. Particle-size features of the plume dust indicated a distant source. The distribution of dust-particle sizes was uni-modal with a mean of 3 μm at 10 m. Calculated vertical dust fluxes indicated that, upon arrival of the plume, the vertical flux of particles was not in equilibrium with the local wind shear. This was the result of the very high mass concentrations of dust in the atmosphere. After the peak levels of concentration had passed, the relationship between vertical dust flux and wind shear velocity tended towards a relation which predicts dust moving upwards through the atmosphere, varying with wind shear velocity to the fourth power.