Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Desert dust feeds tropical rainforest

30.10.2006
The Amazon rainforest in South America relies on dust transported by winds from the Sahara desert in North Africa to replenish the nutrients and minerals in its soils.

For the first time, scientists have proved that over half the dust transported to the Amazon comes from one location in the Sahara, the Bodélé depression, even though it makes up less than 1% of the Sahara. Without this supply of dust to replenish the nutrients in its soils, the Amazon could become a wet desert.

The work is reported today in the first edition of the Institute of Physics open-access journal, Environmental Research Letters.

Dr Ilan Koren, lead author of the paper said: “The Bodélé is known as the largest source of dust in the world, but until now no-one had any idea how much dust it emits and what portion arrives in the Amazon. Using satellite data, we have calculated that it provides on average more than 0.7 million tons of dust on each day that it is actively emitting dust. It is most active during the winter and spring seasons unlike most of the other areas in the Sahara that emit dust. This is due to the seasonal shift of the surface winds of the Sahara.”

The Bodélé just 0.5% of the size of the whole Amazon yet it contributes almost half the amount of dust needed there to replenish the soils each year.

The most important condition for dust emission is surface wind speed. During the winter, strong surface winds (the Harmattan winds) occur along the southern border of the Sahara closer to the Sahel zone of west-central Africa. The Bodélé is a depression located downwind of a huge crater-like valley formed by the Tibesti and Ennedi mountains near the northern border of the Sahel. This crater narrows to a cone-shaped pass in the southwest corner of the valley. The shape of the pass focuses the winds like a lens focussing light and they speed up towards the Bodélé. It is the unique structure of the pass and the location with respect to the surface winds that causes the Bodélé to produce such a large amount of dust.

Dr Koren continued: “In the early morning on an emission day the winds speed up to the critical velocity for lifting and transporting dust when they reach the Bodélé. By using data from two satellites that take images of the same areas three hours apart, we can estimate the wind speed and calculate the size of the “dust parcels” that are produced at the Bodélé. We are then able to track the progress of the parcel the next day after it has left the Bodélé and watch it progress across the desert.”

“One satellite, MODIS, has extensive coverage of the area but doesn’t tell us anything about the quantities of dust over land whilst another, the MISR instrument, covers a very small area of land but can retrieve dust properties. Our work using data from both together for the first time has given us a valuable insight into the quantities of dust that are transported from the Bodélé. However this leads to more key questions: How long has the Bodélé emitted such a huge amount of dust to the Amazon and how long will it continue to do so? There has been a recent expedition to the area and we hope that further analysis from this and more satellite imaging that we will be able to answer these and further questions.”

Dianne Stilwell | alfa
Further information:
http://www.iop.org

More articles from Earth Sciences:

nachricht Live from the ocean research vessel Atlantis
13.12.2018 | National Science Foundation

nachricht NSF-supported scientists present new research results on Earth's critical zone
13.12.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>