By Peter Kuchar
Recently on 23rd of February I was witness of really amazing event, strongest dust storm in recent history of Canary Islands. Most of you probably know, but those wonderful islands are located 100 to 400 kilometers west from Africa coast of West Sahara. Dust is not unknown there, in facts those volcanic islands thanks to Sahara sand for their awesome beaches.
But this one was unprecedented. Sun disappeared, everything covered in martian orange hue, wind howling up to 150km/h. Concerned sights of airplanes making their final approach in ~500m visibility in sand and wind over 100km/h. Luckily all of them made it till final closure of airport.
Here are few examples how it looked:
Try to find airplane on this one…
Color of images corresponds with reality and please have on mind this was midday with subtropical sun high on sky.
And what exactly happened? Apparently there is exceptional situation with Jet Stream. It is not unseen to split into two, but usually one of those two is just short lived an weak. This time it was quite different. Both legs were strong. One coming through central US, passing Newfoundland, United Kingdom and central Europe. Second one coming from Caribbean through West Sahara and Mauritania to Algeria, Libya and Egypt. I’m looking on Jet Stream behavior for few years and this is unusually low south.
Those two high speed streams of air are creating situation for circular convection in between them.
Let’s look on situation on 23rd of February:
There is cyclone with center north of Canary Islands. Lifting sand in West Sahara and Mauritania and distributing it counterclockwise above Atlantic Ocean.
And this is like it was looking from satellite:
This is about time when it was worst on Canary Islands, but this cyclone is still going on.
Two days later situation looks like this:
Dust cloud covers substantial part of globe area and should definitely have impact on global temperature.
It is proven that during Ice Ages dust level in atmosphere is very high. The higher dust content the colder.
This event was exceptional, but if for some reasons this becomes periodical it can have serious impact on climate, I dare to say it can trigger descent to Ice Age.
All this is caused by position of Jet Streams and those are defined by position of Hadley, Ferrel and Polar cells.
Exact position of them has many variables like atmosphere pressure, speed of Earth rotation and probably Sun/Earth magnetic field.
If for some reasons Jet Stream will be located in such configuration, that dessert parts of globe will be close to its path,it will cause dust events on periodical and probably permanent basis rapidly changing Earth climate.
Peter Kuchar
Unprecedented? I doubt it. There used to be an extinction monitor located at the La Palma Cumbre Viejo observatory. That is an instrument that measures the transparency of the atmosphere which is obviously an important quantity to know at an observatory. I visited the place quite regularly in the 1990s and had occasionally the bad luck of not being able to observe at all because of Saharan Dust. The dust record used to be publicly accessible.
Saharan dust deposits have been found as far away as the Amazonian rainforests.
Without Sahara, no Amazonian rainforest .
NASA Satellite Reveals How Much Saharan Dust Feeds Amazon’s Plants
A new paper published Feb. 24 in Geophysical Research Letters, a journal of the American Geophysical Union, provides the first satellite-based estimate of this phosphorus transport over multiple years, said lead author Hongbin Yu, an atmospheric scientist at the University of Maryland who works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. A paper published online by Yu and colleagues Jan. 8 in Remote Sensing of the Environment provided the first multi-year satellite estimate of overall dust transport from the Sahara to the Amazon.
worth reading too</a<
I experienced the Harmattan in Nigeria in mid 1960s, winds carrying red dust from the Sahara, strongest between November to March. The red sky is the same as in your pictures. The inside of your shirt collar is red, and white shirts take on a pale pinkish color!
Perhaps the configurations you analyzed are uncommon, the Harmattan is not. It happens over several months each year. The stiff breeze highly likely creates cyclonic patterns at the boundaries of the rapidly flowing air masses that you depict. Although it may be uncommon over the Canaries it shouldn’t be as a general phenomenon.
https://www.britannica.com/science/harmattan
It is not uncommon to get high altitiude dust drom the Gobi in the Pacific NW-due to high altitude jet stream, Usually in the spring and can bring a fine hazy dust that is yellowish in color.
This Possibility of a Worldwide/Hemisphere event is interesting. I remember Pinatubo’s effect and the fact it might have killed of the El Nino of the ’92 season..i do believe this is going to be -“Interesting” hopfully not Spockian “Interesting” as in popping out of warp in the middle of a KIlingon Battle fleet…
I am afraid I cannot subscribe to this explanation:
Another ready-made explanation that fails to look at the genesis of the situation in the lower layers.
Starting with a 1035 hPa Mobile Polar High from Greenland on Feb 20 2020 that invaded the North Atlantic down to the Azores. On Feb 21, a Quebec originated 1025 hPa MPH cut off cold air supply of the previous one and, unable to displace the denser 1035 hPa air mass of the previous MPH, started to spread around the HP knob SW and NE toward respectively the eastern Seaboard and Europe, giving one the strong wind storm northern France and UK experienced after the passage of the Dennis one.
That dynamic situation squeezed the remnants of the Greenland MPH from Western Europe toward the Atlantic, feeding a strong NE-SW flow of still relatively dense air, reinforcing the knob and maintaining its 1035hPa. That flow created the vortex of the Canary Islands and when dense air finally reached the African shores, it acted like a Haboob, shaving sand and sending it spiraling into that depression vortex.
This synoptic situation prevailed until the 25 Feb, which is until the former 1035hPa air mass finally got tropicalized and moved westward agglutinating to some previous tropicalized air mass near the Caribbeans and the flow slowed down, diminishing the vortex.
As for this:
If anything, this event is the result of a specific synoptic situation brought in by colder/denser descent of air masses from Polar Regions, through Greenland and Quebec. Greenland experienced record cold temperature this winter and quite high pressures.
Ice ages dust was the result of high pressure anticyclonic conditions brought by the rapid descent of very cold air masses from Polar Regions, generating haboob events when encountering dry soils and desert sands. This may become a retro-action enhancing colder conditions but, again, it is only a consequence of already colder/denser air masses invading deeper southward, hardly what periods of general warming have produced.
Turbulent fluid flow.
It is dust, not sand. Mostly silt-size particles less than 1/16 mm dimension.
If this continues off and on for decades or centuries, it is climate, otherwise this one event is just turbulent weather. Many examples in the earth’s geologic record of significant deposits of “dust”. These deposits are called loess. As much as 100 meters thick in China. Loess hills in Iowa; loess in eastern Washington state, and so forth around the world.
Sand – small particles of natural mineral origin
Dust – fine particles of any origin.
Small includes fine.
So if you say Sand to some dusty dune on Sahara it is ok.
And I think it is ok to say Sand to fine particles in air to emphasize its mineral origin.
Sand is a size term, unrelated to composition (so you can have sands made of plastic or foraminifera). One of the features of sands made of minerals is that even strong winds cannot lift mineral sand grains high into the atmosphere and the weight of the sand grain brings it down to the surface down flow. Upon hitting a surface composed of other sand grains it dislodges some which rise up and get caught up by the wind to travel downwind only for them to be brought down to the surface and dislodge more sand grains. This process, called saltation, can best be experienced on a windy day on a dry beach when the lowest few feet of the air are full of moving sand grains, but above a certain level the air is completely sand free. Your legs and lower body may get sand blasted but your head can be sand free.
Only fine silt and clay grains (also size terms) can be lifted by the wind high into the air to create dust-clouds and dust-storms. Because there are adhesive forces between clay sized mineral particles, the wind can only lift dry fine-grained sediments. Sediment-laden air (except close to the ground) never contains sand grains, so when it forms part of weather phenomena these are best referred to as “dust storms”.
From Wikipedia:
The entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Depression
https://en.m.wikipedia.org/wiki/Diatom
In the center of the Bodélé depression there still is a lake: lake Chad which gave its name to the country of Chad.
Two years ago I was in Lanzarote, one of the Canary Islands. The beaches on the west coast are black (basaltic grains with some olivine), beaches on the north-east coast are white, I suppose seashell fragments, have to check (took a sample).
“n the center of the Bodélé depression there still is a lake: lake Chad”
No. The Bodélé depression is a separate basin, actually lower than lake Chad. When lake Chad was higher than now it occasionally overflowed into it. And Lake Mega Chad, which only exists when climate is considerably warmer than now (yes warmer) comprises both basins.
The African dust supplies important mineral-nutrients for the N Atlantic zooplankton.