Asian dust events of April 1998
Asian dust events of April 1998
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DOI：
10.1029/2000jd900788
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发表时间：
2001-08-27
影响因子：
4.4
通讯作者：
Malm, WC
中科院分区：
文献类型：
--
作者：
Husar, RB;Tratt, DM;Malm, WC
1998年4月15日和19日，春季低压系统从西北方向下降，在戈壁沙漠上空产生了两次强烈的沙尘暴。在SeaWiFS卫星图像、常规地面监测和偶然观测中，探测到了被风吹起的尘埃，并在其演变之后发现了黄色。4月15日的沙尘云是再循环的，它被东亚上空的一个降水天气系统带走。4月19日的沙尘云在5天内穿越太平洋，沿着不列颠哥伦比亚省和加州州之间的山脉沉降到地表，严重影响了该地区的光学和浓度环境。在东亚，尘埃云使无云海洋和陆地的反射率增加了10- 20%，但它降低了近UNI云的反射率，导致所有表面呈黄色。尘埃的黄色后向散射无法用具有恒定折射率的简单米氏理论进行合理的解释。在西海岸上空，沙尘层使光谱均匀的光学厚度增加到约0.4，使太阳直接辐射减少了30- 40%，漫射辐射增加了一倍，并使蓝色的天空变白。4月29日，西海岸山谷上空的平均过量地表沙尘气溶胶浓度约为20-50 mug/m3，局部峰值大于100 mug/m3。尘埃质量的平均直径为2-3妈妈，和灰尘的化学指纹是显而易见的整个西海岸，并延伸到明尼苏达州。1998年4月的沙尘事件对地面气溶胶浓度的影响是1988年以来任何其他沙尘事件的2-4倍。一个特设的国际网络虚拟社区对沙尘事件进行了观测和解释。建立一个由社区支持的网络基础设施，监测全球气溶胶模式以发现此类极端气溶胶事件，向有关社区发出警报和提供信息，并促进合作分析，以改善空气质量和灾害管理，将是有益的。
On April 15 and 19, 1998, two intense dust storms were generated over the Gobi desert by springtime low-pressure systems descending from the northwest. The windblown dust was detected and its evolution followed by its yellow color on SeaWiFS satellite images, routine surface-based monitoring, and through serendipitous observations. The April 15 dust cloud was recirculating, and it was removed by a precipitating weather system over east Asia. The April 19 dust cloud crossed the Pacific Ocean in 5 days, subsided to the surface along the mountain ranges between British Columbia and California, and impacted severely the optical and the concentration environments of the region. In east Asia the dust clouds increased the albedo over the cloudless ocean and land by up to 10-20%, but it reduced the near-UNI cloud reflectance, causing a yellow coloration of all surfaces. The yellow colored backscattering by the dust eludes a plausible explanation using simple Mie theory with constant refractive index. Over the West Coast the dust layer has increased the spectrally uniform optical depth to about 0.4, reduced the direct solar radiation by 30-40%, doubled the diffuse radiation, and caused a whitish discoloration of the blue sky. On April 29 the average excess surface-level dust aerosol concentration over the valleys of the West Coast was about 20-50 mug/m(3) with local peaks > 100 mug/m(3). The dust mass mean diameter was 2-3 mum, and the dust chemical fingerprints were evident throughout the West Coast and extended to Minnesota. The April 1998 dust event has impacted the surface aerosol concentration 2-4 times more than any other dust event since 1988. The dust events were observed and interpreted by an ad hoc international web-based virtual community. It would be useful to set up a community-supported web-based infrastructure to monitor the global aerosol pattern for such extreme aerosol events, to alert and to inform the interested communities, and to facilitate collaborative analysis for improved air quality and disaster management.