July 3, 2014 - Saharan dust approaching South America

Saharan dust approaching South America

A long stream of dust and sand crossed the Atlantic Ocean in late June, 2014, bringing a tan haze to parts of South America and the United States. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured a true-color image of the event on June 25, 2014.

The dust blows from the northeast to the southwest in this image. The densest layer of dust completely obscures the blue water from view, but dust is not confined to the dark central stream. A broad tan veil of varying hues can be seen throughout the image, hanging in the atmosphere under the white clouds. The coast of South America lies in the southwest corner of the image. Although the green land is nearly completely hidden underneath cloud and dust, black borderlines delineate the boundaries of Brazil, French Guiana and Suriname (east to west).

From late spring to early fall, strong winds in West Africa frequently kick up massive dust storms which sometimes travel over the Northern Atlantic Ocean via the Saharan Air Layer – a layer of warm, dry air from the desert which rises high over the cooler, moister air sitting over the water. The layers don’t mix, allowing the dust and sand to catch the “express train” ride to South America and the United States.

On June 30, Saharan dust was spotted and photographed suspended over the Arkansas River Valley in the state of Arkansas, and a heavy stream of dust was visualized by satellite moving over the eastern Texas coast. Smaller amounts of dust were visualized as far north as Iowa, Illinois and Nebraska, eastward to Tennessee and Kentucky, and westward to New Mexico on that same day.

The Cooperative Institute for Meteorological Satellite Studies (CIMSS) posts a Saharan Air Layer tracking product on their public website, which allows visualization of the SAL layer as it moves off of western Africa. To view the latest SAL Tracking Product, go to: http://tropic.ssec.wisc.edu/real-time/sal/splitE/movies/splitE5.html

Image Facts
Satellite: Terra
Date Acquired: 6/25/2014
Resolutions: 1km (702.7 KB), 500m (2.3 MB), 250m (5.2 MB)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC