Saharan dust invades Portugal and Spain

Today’s Image of the Day from NASA Earth Observatory features Saharan dust invading Portugal and Spain in late March 2024. Sand and dust particles are lifted into the atmosphere and transported by hot winds known as the “calima.” 

“Suspended particles reached the region on March 21, coloring skies orange and degrading air quality for several days,” said NASA.

“The MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite captured this image of dust enveloping the Iberian Peninsula on March 22.” 

“On that day, snowy slopes at a ski resort near Granada were tinged with brown from dust deposition and other areas saw ‘muddy’ rain, according to news reports.”

Increasing frequency of Saharan dust intrusions

In a recent study, experts noted that the frequency and intensity of wintertime Saharan dust intrusions are on the rise. 

“While winter 2023 was comparatively calm in terms of dust, the extreme events are back in 2024, the study authors said in media coverage. In addition to the March storm, powerful winds sent desert dust streaming over the Canary Islands and north toward the U.K. in January 2024,” said NASA.

“The researchers suggested several factors that may be contributing to these recent intense events. One is an ongoing drought in northwest Africa increasing the amount of dust that can be carried away by the wind.” 

“Another is ‘blocking’ weather patterns that divert the jet stream and result in winds more often blowing north from the Sahara.”

Wintertime Saharan dust intrusions 

Saharan dust intrusions can have significant impacts on air quality, weather, and climate in the receiving regions. Here’s a detailed overview:

Origin and mechanism

• Origin: The Sahara Desert is the world’s largest hot desert, and it’s a significant source of mineral dust in the Earth’s atmosphere. Dust storms can lift millions of tons of sand and dust into the atmosphere.
• Mechanism: These dust particles are transported by the wind across thousands of kilometers. The transport mechanism involves atmospheric features like the African Easterly Jet, trade winds, and low-pressure systems that can carry the dust over the Atlantic Ocean to the Americas, north to Europe, or east towards Asia.

Intensity factors

The intensity of Saharan dust intrusions, especially during wintertime, can be influenced by several factors:

• Meteorological conditions: Wind speed, atmospheric stability, and the presence of cyclonic systems can enhance or inhibit dust uplift and transport.
• Saharan climate: Seasonal variations in temperature and precipitation in the Sahara affect dust availability and emission rates. Wintertime can sometimes see reduced dust activity compared to the peak in the summer, but significant events can still occur.
• Atmospheric pathways: The specific atmospheric conditions, including the path taken by the dust-laden air masses, can affect the distance and areas affected by dust intrusions.

Impacts

• Air quality: Saharan dust intrusions can lead to deteriorated air quality in affected regions, posing health risks to humans, especially concerning respiratory issues.
• Weather and climate: The dust particles can influence weather patterns by affecting the radiation balance in the atmosphere. They can lead to cooling of the surface and heating of the atmosphere, which can modify cloud formation and precipitation patterns.
• Ecosystems: Dust deposits can impact ecosystems by supplying nutrients to marine and terrestrial ecosystems but also by potentially harming sensitive habitats.

Wintertime specifics

Wintertime intrusions, while generally less intense than summer events, can still have significant impacts. The frequency and intensity of these intrusions can vary from year to year, influenced by broader climatic patterns such as the North Atlantic Oscillation (NAO) and the El Niño Southern Oscillation (ENSO).

Monitoring and research

Advancements in satellite remote sensing and ground-based measurements have improved the monitoring and understanding of Saharan dust intrusions. Research continues to focus on quantifying their impacts on climate, human health, and ecosystems, as well as predicting their timing and intensity with better accuracy.

Understanding the dynamics of Saharan dust transport is crucial for preparing and mitigating its impacts on human health, ecosystems, and climate. Continuous research and monitoring efforts are essential to grasp the full scope of its effects and variability, especially in the context of climate change.

Image Credit: NASA Earth Observatory

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–