Saharan Dust Analysis

From NASA

NASA-NOAA’s Suomi NPP Satellite Analyzes Saharan Dust Aerosol Blanket

Dust storms from Africa’s Saharan Desert traveling across the Atlantic Ocean are nothing new, but the current dust storm has been quite expansive and NASA satellites have provided a look at the massive June plume. NASA-NOAA’s Suomi NPP satellite showed the blanket of dust had moved over the Gulf of Mexico and extended into Central America and over part of the eastern Pacific Ocean.

Suomi NPP OMPS aerosol index image

This June 24, 2020 image is from the Suomi NPP OMPS aerosol index. The dust plume moved over the Yucatan Peninsula and up through the Gulf of Mexico. The largest and thickest part of the plume is visible over the eastern and central Atlantic.Credits: NASA/NOAA, Colin Seftor

NASA uses satellites and other resources to track aerosol particles made of desert dust, smoke, and volcanic ash. The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image while the Ozone Mapping and Profiling Suite (OMPS) Nadir-Mapper (NM) instrument aboard the Suomi-NPP satellite provided absorbing aerosol index values. The OMPS index indicates the presence of light absorbing aerosol particles (ultraviolet (UV)-absorbing particles in the air) such as desert dust. The absorbing aerosol index is related to both the thickness and height of the aerosol layer.

The Absorbing Aerosol Index is useful for identifying and tracking the long-range transport of volcanic ash from volcanic eruptions, smoke from wildfires or biomass burning events and dust from desert dust storms. These aerosol particals can even be tracked over clouds and areas covered by snow and ice.

This "true-color" composite image of the Saharan Dust plume was captured by the VIIRS instrument aboard NASA/NOAA’s Suomi.

This image is a composite of the OMPS aerosol index and the VIIRS visible image both from NASA/NOAA’s Suomi NPP satellite on June 24. The image shows the dust plume moved over the Yucatan Peninsula and up through the Gulf of Mexico.Credits: NASA/NOAA, Colin Seftor

Colin Seftor, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., created imagery from the Suomi NPP OMPS absorbing aerosol index and visible imagery from the VIIRS instrument He said that on June 23 and 24 the dust plume had moved completely over Mexico’s Yucatan Peninsula, up through the Gulf of Mexico and into southern Texas. “At that point, the situation becomes more complicated because the absorbing aerosol index signal seen further north into Texas, Oklahoma, Nebraska, etc., is probably a mix of dust and smoke from the numerous fires burning in the southwest U.S. You can also see that the dust traveled over Central America and out into the Eastern Pacific Ocean.”

On June 25, an animation that combined OMPS aerosol index and VIIRS visible imagery from NASA/NOAA’s Suomi NPP satellite was created at NASA Goddard showing the movement the Saharan dust cloud from June 15 to 25, 2020,. The animation showed the dust plume streamed from Africa’s west coast over the Atlantic into the Caribbean Sea and up through the Gulf of Mexico over some of the Gulf states. 

Aerosol particles absorb and scatter incoming sunlight, which reduces visibility and increases the optical depth. Aerosol particles have an effect on human health, weather and the climate. Aerosol particles are produced from many events including human activities such as pollution from factories and natural processes such as smoke from fires, dust from dust storms, sea salt from breaking waves, and volcanic ash from volcanoes. Aerosol particles compromise human health when inhaled by people with asthma or other respiratory illnesses. Aerosol particles also affect weather and climate by cooling or warming the earth as well as enhancing or preventing cloud formation.

This image is a composite of the OMPS aerosol index and the VIIRS visible image.

This “true-color” composite image of the Saharan Dust plume was captured by the VIIRS instrument aboard NASA/NOAA’s Suomi NPP satellite on June 24, 2020. The bright streaks seen at regular intervals are due to sun glint off of the ocean surface.Credits: NASA/NOAA, Colin Seftor

On June 18, NASA’s Earth Observatory noted the thickest parts of the plume appeared to stretch about 2,500 kilometers (1,500 miles) across the Atlantic Ocean. By June 24, the plume extended over 5,000 miles.

Dust from Africa can affect air quality as far away as North and South America if it is mixed down to ground level. But dust can also play an important ecological role, such as, fertilizing soils in the Amazon and building beaches in the Caribbean. The dry, warm, and windy conditions associated with Saharan Air Layer outbreaks from Africa can also suppress the formation and intensification of tropical cyclones.

“While Saharan dust transport across the ocean to the Americas is not uncommon, the size and strength of this particular event is quite unusual,” Seftor said. “Also, if you look off the coast of Africa you can see yet another large cloud coming off the continent, continuing to feed the long chain of dust traveling across the Atlantic.”

Animated GIFs of the dust storm’s activity:

This animation shows the aerosols in the Saharan dust plume from June 15 to 25, 2020.

This animation shows the aerosols in the Saharan dust plume from June 15 to 25, 2020. It was created from the Suomi NPP OMPS aerosol index. The dust plume moved from Africa’s west coast over the Atlantic Ocean into the Caribbean Sea and up through the Gulf of Mexico. The largest and thickest part of the plume is visible over the eastern and central Atlantic.Credits: NASA/NOAA, Colin Seftor

This "true-color" composite animation of visible satellite imagery shows the movement of the Saharan Dust plume Jun 15-25, 2020.

This “true-color” composite animation of visible satellite imagery shows the movement of the Saharan Dust plume from June 15 to 25, 2020. It was captured by the VIIRS instrument aboard NASA/NOAA’s Suomi NPP satellite. The bright streaks seen at regular intervals are due to sun glint off the ocean surface.Credits: NASA/NOAA, Colin Seftor

Animation showing dust cloud combining OMPS aerosol index and VIIRS visible imagery from Suomi NPP.

This animation of the progression Saharan dust cloud across the Atlantic Ocean from June 15 to 25, 2020 combines OMPS aerosol index and VIIRS visible imagery from NASA/NOAA’s Suomi NPP satellite. The dust plume moved from Africa’s west coast over the Atlantic into the Caribbean Sea and up through the Gulf of Mexico. The largest and thickest part of the plume is visible over the eastern and central Atlantic Ocean.Credits: NASA/NOAA, Colin Seftor

By Rob Gutro  
NASA’s Goddard Space Flight Center

Last Updated: June 26, 2020

Editor: Lynn Jenner

39 thoughts on “Saharan Dust Analysis

  1. A positive outcome of the climate scare is the vastly expanded resources applied to collecting atmospheric data. Hope these resources stay with us when the climate scare rolls over to the next big eco whacko worry whatever that may be.

    PS: what I had written about 30 years ago:

    “as the sahara desert expands southward, dust storms like this (photo) carry a billion tons per year of african topsoil to the new world in plumes of red-brown clouds across the atlantic (photo, photo). the dust is deposited in the s.e. united states, the caribbean, and the amazon basin. this photo shows dust settling on the bahamas where agriculture depends on african soil. the dust is rich in nutrients but also contains live insects, microorganisms, and fungi. red sunsets in florida, usually in july, signal the arrival of african dust. there is a lot of africa in america”.

    From my old blog:
    http://chaamjamal.blogspot.com/2019/12/a-version-of-old-wbt-page-preserved-by.html

    • Similarly, North America gets a lot of dust from the west, China mainly, usually in winter and spring. It becomes especially visible on snow. It’s not really significant some years, but then other times it is quite intense.

    • However, as the Sahel has been getting a bit smaller, it’s more like large storms occasionally occur and not due to more desert.

  2. We need to address this great climate threat. We should tax all countries that have sand….

  3. What? No mention of it being caused by CO2? They must have enough funding at the moment then.

  4. But dust can also play an important ecological role, such as, fertilizing soils in the Amazon.

    ??? I thought the desert dust was just silicon dioxide. Apparently not.

    • Way Cool!

      Everything you wanted to know about dust in one easy-to-read paper.
      Fe for ocean fertilization present at ~ 3% to 4% by weight. Way more than I would have expected.
      One very interesting and informative link.

      • Was looking for some mention of the fertilizer effect.
        So there should be a bloom in phytoplankton and in fish. Wonder how long it takes to see a net effect.

      • Iron is why the dust is red. I had a heck of time varnishing outdoors back in the 1970s unless I varnished only at night. Dust ruined everything during the winds of the day.

    • commiebob,
      Thanks for the link! That answered several questions I had about dust elemental composition and potential for iron fertilization effects on the Atlantic ocean and Caribbean sea.

  5. One can see it’s breaking up and behind it will almost certainly come a tropical wave or more likely a series of them. Lots of moisture over Africa going to head this way. Good chance we’re going to see some tropical storm activity fire up again in a couple weeks or so.
    So far we’ve actually been pretty lucky. Florida got it’s drought relieved to a large extent and drought is not a serious problem hardly anywhere in the lower 48. Tornadic activity is well below average. The worst seems to have hit the cotton crops in TX, AR, and SE MO where it’s been too wet. But good for the rice.

    • The peak of hurricane season is still a couple of months away. Right now we’re at peak of Saharan Air Layer (SAL) outbreaks. As summer progresses subtropical ridge moves north and SALs taper off. Conditions for tropical cyclones improve over deep tropics and hurricane activity ramps up. We see cycle over and over again each year.
      Thankfully NASA didn’t infect this article with climate nonsense.

      • Many prognosticators, including Joe Bastardi, have been saying conditions are good for early TS development. We have already seen it in fact.

        • The three named ‘tropical’ cyclones thus far have all been hybrids systems, not truly tropical. This is common for early season activity. But they are not a good measure of how active main season will be. The seasonal forecasts are for above average activity, but early season activity is not necessarily an indicator.

  6. Two nights ago, in Central Florida, I went out at around 9:30 PM, having read late that day, on Zerohedge.com, “3,500 Mile-Long “Godzilla Dust Cloud” Will Hit US Southeast Within Hours”
    We have a number of LED lanterns in our naturally landscaped front garden, and one is a spot, pointing out to our van. At first I was confused, thinking my 77 year old eyes were failing further, as a mist appeared to be filling the area in front of the spot. Only later I realized it was probably the Saharan dust. The humidity at 9:30 is not normally high enough for fog. Wow!

  7. I live just south of Tulsa, OK. Yesterday evening you could see the dust in the air. Looking into the distance down a straight road was a slightly pinkish-tan fog. Strong winds were blowing up from the south, 25+ knots. No odor, no fine particles you could feel, just a faint fog. Very surreal.

  8. Works both ways! In southern Argentina the howling winds (one day in 1997 24 hour average just over 100 mph, from Mantenial Espejo weather station) move the ash from Volcano Hudson eruption and also cause deflation basins. The Gran Bajo de San Julian, located about 20 kilometers from the Atlantic Ocean, is 105 meters below sea level, and is the lowest point in the western hemisphere. Although some tectonic tilting got the depression started the howling winds found silty layers that were picked up and transported off to the east (Africa, anyone?). When I went down into the depression my gps read negative numbers. Stay sane and safe.

  9. You will notice that most of the dust has gone around Florida. The reason is a blocking high over the NE Gulf of Mexico which has been in place for about a week. That is the main cause of the hot dry weather currently in central Florida, That high is breaking down and we should see more normal summer weather next week.

  10. “Aerosol particles also affect weather and climate by cooling or warming the earth as well as enhancing or preventing cloud formation.” I like settled science.

    • You forgot this point too…

      Aerosol particles also affect weather and climate by cooling or warming the earth as well as enhancing or preventing cloud formation.

      If that doesn’t narrow it down, I don’t know what does :-/

  11. How high does this dust extend?
    I was wondering if dust would have the same affect on jet engines that volcanic ash does.

    • The tropopause will prevent this.

      Very srtong volcanic plumes can punch through this layer which is why commercial jets get affected by large eruptions

  12. On the end of February I posted here article about dust storm on Canary Islands I witnessed. I wrote this time it was unprecedented, but some people doubted that. From this time dust events are going on and increasing. We are on the brink of change here. This is how ice ages begins. It is getting dustier.

    • One of the proposed causes of the more extreme melting of Greenland and Arctic sea ice in 2012 was a large Saharan dust cloud that winds diverted northward all the way to Greenland that year.

      I know WUWT carried the story but I can never get the search feature to divulge what I want.

  13. The Amazon basin depends on African dust to replenish the nutrients washed away by heavy rains each year.

  14. Why didn’t people talk about this virus transport research?

    Viruses are by far the most abundant microbes on the planet, with estimated 1030 virus particles in the oceans alone [1]. They encompass much of the biological diversity on the planet, catalyze nutrient cycling, and affect the microbial makeup of communities through selective mortality [2, 3]. Despite the high genetic diversity within viral communities, the observation has been repeatedly made that identical or nearly identical virus sequences can be found in widely separated environments that are environmentally very different [4, 5]. The explanations for these observations are (1) that closely related microbes that can serve as host cells for these viruses must live in very different environments, (2) that the viruses must have very broad host ranges that allow them to infect distantly related hosts, or (3) that the dispersal of some viruses is so high that they are distributed globally. Although there is theoretical [6] and empirical [7, 8] evidence of viral dispersal at the Earth’s near-surface, there are no data that quantify the magnitude of this dispersal for the free troposphere.
    https://www.nature.com/articles/s41396-017-0042-4?fbclid=IwAR2E1rIAiOor5xU_RT5fEcfq0buzq7aeCJx5wlDfT_YVuERrMpW0RIxlrbQ

  15. Any idea how much this Sahara dust affects sea level rise? That added mass to the oceans along with meteoric dust and debris, river sedimentation (deltas) seafloor spreading, volcanoes, etc. has to displace some amount of water. The only question is: how much?

    • I was putting this question here few years ago. Response is – a lot.
      Form 3mm /year sea level rise probably 1 – 2 mm is caused by processes you mention.
      Ocean area is 361 million km2. So to rise it 1mm you need 361 kubic kilometers of submerged matter.
      This is all river sediments, meteors, space dust, coastal erosion, organic matter (carbonates) sinking.

  16. These aerosol particals can even be tracked over clouds and areas covered by snow and ice.
    Say what?

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