EGU Blogs

Sand gets everywhere

Saharan dust is currently escaping the confines of the desert and making a break for it over the Atlantic Ocean towards South America.

Below is a true colour image from the MODIS instrument on the TERRA satellite from this morning (6th June). You can see the dust from the desert over the ocean; note the constrast between the darker blue ocean surface and the lighter shade where the dust resides.

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Image of the dust plume on 6th June 2014 from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the TERRA satellite. Image courtesy of NASA. The strip of bright light across the image is due to sun glint, where sunlight reflects off the ocean surface. Click on the image for a larger view.

Below is the same image but with Aerosol Optical Depth (AOD) overlaid. This provides a measure of the total amount of aerosol particles in the atmosphere. The red portions are values above 0.7, which is quite elevated (anything above 0.3 would be fairly polluted).

Such incidences aren’t particularly unusual and the dust actually acts as a natural fertiliser for the ocean! Dust from the Sahara has also been observed to reach the Amazon rainforest. There are some more satellite images here on the OMPS blog.

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Image of the dust plume on 6th June 2014 from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the TERRA satellite. Aerosol optical depth from MODIS is overlaid to highlight the location of the dust. Image courtesy of NASA. Click on the image for a larger view.

Dust from the Sahara is also moving across western Europe heading for the UK based on this forecast from the University of Athens, which was highlighted by the Defra Twitter account.

This follows the pollution episode that struck the UK in early April, where Saharan dust combined with pollution from continental Europe and the UK. On this occasion though, thunderstorms are expected during Saturday, which will likely reduce any build-up of pollution and also wash out the dust from the atmosphere.

A sprinkling of dust might be found on cars in the south-east should the forecasts pan out. Dust gets around.

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Will Morgan is a Post-Doctoral Research Fellow at the Centre for Atmospheric Science at the University of Manchester, UK. His research focusses on measurements of the chemical composition of aerosols and how this impacts air quality and climate. He is usually found at a computer in an office or on a research aircraft travelling a few hundred metres above the ground. Will also contributes to a podcast about atmospheric science called The Barometer. Tweets as @willmorgan.