African Dust and Its Impact on Climate Xiaoyu Liu MPO

 Outline  What is african dust?  What is its physical property?  How does it affect climate?  The future work

 Who is who?

 Two conditions to product dust  The appropriate meteorological conditions to supply momentum to the surface.  The appropriate soil conditions to allow dust production.

 Why it is so important?

 Look at its location

 Its impact on climate  Change the local climate  Global warming  Change the strength of hurricane  Ruin the marine ecosystem

 Change of the local climate  Sahara Desert and Dusty Sahel Block "Normal" Movement of Monsoon and Winter Rains

 Due to the maximum latitude of the Sun's position during seasonal changes, the maximum differential heating occurs closest to the equator. The bounded areas show where monsoonal flow occurs most often.

 Global warming  It is a significant source of climate warming for the dusty Sahelian airs do capture, store and transport solar heat that would otherwise be dissipated in normal rainfall.

 Change of the strength of hurricane  Sahelian dusts and the supersaturated airs that flow over the Eastern Atlantic Ocean region in which most hurricanes are spawned, are a significant source of energy for the formation of hurricanes.  The hurricane "season" is also exactly the season of the Sahelian dust flow.

How is hurricane formed Hurricanes form where ocean waters are warmed to temperatures of greater than 77 degrees Fahrenheit. The formation starts when micro-cyclonic air motion at the sea surface induced by rapid evaporation and accelerated by wind induced turbulence at the water-air interface. The micro-cyclones become a cyclonic storm when sufficient energy is injected into aggregating micro- cyclonic systems.

 The Sahelian air is a high energy source that flows into spawning zone at the time of hurricane formation.  This is because the Sahelian air is supersaturated with moisture.  Though the air is too hot for mineral dust particles to nucleate precipitable moisture, the ocean atmosphere and the micro- cyclonic systems are full of salt particles, which are efficient nucleators.  When the marine salt particles are lofted into the Sahelian air, nucleation does occur with release of large amounts of energy at all altitudes.

 “Take a deep breath in Miami this summer and chances are you'll inhale a bit of Africa.”

 Ruin the marine ecosystem  The degradation of Caribbean marine species appears to be related to major El Niño events.  Land sources of dust plumes in North Africa (Western Sahara and Mauritania) provide more dust to the Atlantic easterly trade winds in major El Niño years.  The dust appears to affect coral and reef- dwelling animals. In Florida waters, Saharan dust brings in a critical nutrient, iron, leading to blooms of toxic algae.

 Protect your lungs  African dust particles contain large amounts of iron as a coating, providing its characteristic red-brown color. Once dust is deposited in the lung, the iron coating would probably be released to the lung tissue.

 Long long way to go……  we should work to remove dust from the Sahelian atmosphere. And there is a proven way to keep significant amounts of dust out of the Sahelian atmosphere. The revegetation of the Sahelian wastelands will suppress the dust. The appropriate proven methods are those used in the United States to cure the 1930s Dust Bowl. They are the methods used by the US Soil Conservation Service (SCS). Modification and use of those SCS methods has already been successful in the Sahel.

THANKS GOD FOR YOUR GIVINGS 谢谢