撒哈拉沙漠卫星图分析

In mid-June 2016, winds lofted thick plumes of dust from northern Africa’s deserts high into the air. When dust gets caught in upper level winds, it can travel long distances and have far-reaching impacts. For instance, dust from Africa helps build beaches in the Caribbean and fertilizes soils in the Amazon. It affects air quality in Europe and North and South America. And dust may play a role in the suppression of hurricanes and the decline of coral reefs.

The map above shows the concentration of aerosols on June 19, 2016, produced with data from the Ozone Mapping Profiler Suite (OMPS) on the Suomi-NPP satellite. High concentrations are represented with shades of deep red; the lowest concentrations are shades of light yellow. The largest, thickest plume appears to stem from the Sahara in western Africa.

When this map was produced, winds had already swept a plume of dust westward over the Atlantic Ocean and the archipelago of Cabo Verde (Cape Verde). A natural-color view of this plume is pictured in the second image, acquired on June 19 with the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi-NPP. A model run by the Barcelona Dust Forecast Center anticipated that the dust would reach the Canary Islands, north of this scene, by June 22.

The top map shows a thinner but measureable plume of Saharan dust also spread north toward Europe. To see how it got there, check out this series of images show ing the plume’s progression since June 16.

The outbreak of dust from the western Sahara was coincident with a plume of dust from Africa’s northeast, carried eastward over the Red Sea. The beginning stages of that storm, triggered by a cold front and turbulent mixing of air, are shown in this image from June 15.

2016年的6月中旬，风把北非的沙漠中的灰尘吹高空中。当灰尘到达上层时，风会把它吹的很远。例如，加勒比海滩和亚马逊的肥沃土壤都来自于非洲的灰尘。它还影响着欧洲和美国北部和南部的空气质量。而且灰尘可能对台风和珊瑚礁的衰退有抑制的作用。

上面的地图显示了2016年6月19日的气溶胶浓度，数据来源于Suomi NPP 卫星上的臭氧的分布映射仪（OMPs）。深红色代表高浓度，浅黄色代表最低浓度。西部非洲的撒哈拉沙漠是气溶胶浓度最高的地区。

6月19日Suomi NPP上的可见红外成像辐射仪（VIIRS）发回了第二张图，

图上有一白色羽毛状物。彼时风已经把沙尘向西吹过了越大西洋和佛得角群岛（佛得角）。根据巴塞罗那沙尘预报中心构建的一个模型预计，沙尘将于6月22日到达加那利群岛北部，也就是这幅图片拍摄地的北部。

上面的地图显示撒哈拉沙尘同时向北波及欧洲，被吹到欧洲的沙尘量很少，但是可以估计其量多少。为了看看沙尘是如何被吹到欧洲的，我们还检查了6月16日以来一系列的图像来追踪进展。

与西撒哈拉沙漠的沙尘外流同时，非洲的东北部的一股灰尘正在跨国红海带向东运动。6月15日的图像显示，这场风暴的初始阶段是由一个冷气流的前端和空气的湍流混合引起的。