A dust storm several hundred kilometers across struck northern Africa on February 23, 2006. The storm carried Saharan dust across Algeria, Tunisia, and Libya, eventually sweeping over the Mediterranean Sea. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard the Aqua satellite took this picture the same day.
The upper right corner of the image shows the “Great Sand Sea” region of the Sahara, while the Rebiana Sand Sea is located in the lower right portion of the image. The left side of the image shows the Algerian section of the Sahara; from north to south, the sand dune desert, or erg, gives way to the rockier “humud,” culminating in the sandstone plateaus shown in the lower left corner of the image. This region is prone to very large storms, which are a hazard to transportation and human health.
South of the dust storm, this picture shows part of the Tassili n’Ajjer National Park in southeastern Algeria. The park stands out from its surroundings due in part to its mountainous landscape. This high plateau in the middle of the Sahara sports some of the world’s most important groupings of prehistoric cave art, recording climate change and animal migrations over the past several thousand years.
In addition to the visible bands used to create this image, MODIS collects data in the broadband thermal portion of the spectrum. Researchers (Ogawa et al. 2004) in the journal Earth Interactions, a publication of the American Meteorological Society, used emissivity and reflectance derived from MODIS data to study the climate of North Africa and the Arabian Peninsula. Other researchers have used MODIS imagery to detect large dust storms which could be used as an early warning system.