Satellite helps Sahel rainfall

2011-06-12 21:26

Paris - Embattled farmers in the Sahel countries of West Africa can take heart from a new study that should boost the accuracy of rainfall prediction in one of the world's most fragile regions.

Sharp differences in moisture in small patches of land can trigger precious rain, says the paper, published online on Sunday in the journal Nature Geoscience.

Researchers from Britain, France and Australia looked at satellite data that located nearly 4 000 rainstorms which occurred in the Sahel between 2006-2010.

Between 80 and 90% of rainfall in the Sahel comes from this kind of storm, which can brew suddenly when moisture-laden air lifts from heated earth.

The scientists then overlaid this data with satellite information on soil moisture.

They found that an area where there are large differences in soil moisture plays a big role in making rain.

A moist area just 10 to 40km across can trigger rain provided it is next to a far drier patch.

This small-is-beautiful finding contrasts with conventional weather models.

These tend to calculate the probability of rainfall on the basis of huge swathes of moist land and on the presence of rain-making features like mountain ranges.

Contrasting soil moisture

"Rainfall is difficult to predict, particularly in regions such as the Sahel where huge storms can grow from nothing in a matter of hours," said lead author Chris Taylor of Britain's Centre for Ecology and Hydrology.

"We found that areas with contrasting soil moisture can play an important role in the creation of new storms, a factor not accounted for in current climate models.

"[...] This effect is important for typically one in eight storms, in a region particularly prone to droughts and associated crop failures."

In areas where there are these sharp differences in soil moisture, rainstorms are twice as likely compared to regions where the moisture level is uniform.

The rain often falls around 10km upwind of the moist patch, not downwind, Taylor explained to AFP.

This occurs when the moist air is driven against weak prevailing winds by a strong local breeze coming from the opposite direction.

The study could help fine-tune knowledge about how climate change could affect the Sahel, he said.

Semi-arid, tropical west Africa is one of the most demanding regions in the world for agriculture, given its fragile soils and a short growing season that is crucially dependent on when and where rain will land.

Read more on:    central africa  |  environment  |  weather
NEXT ON NEWS24X
SHARE:

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
0 comments
Add your comment
Comment 0 characters remaining

Inside News24

 
/News

Jobs in Cape Town [change area]

Jobs in Western Cape region

New Business Corporate Sales Consultant

Western Cape
AGA Recruitment Specialists
R17 000 - R20 000 Per Month

Production Pharmacist

Western Cape
Dante Personnel Recruitment
R40 000 - R45 000 Per Month

MDWA016 COSTING CLERK (9 MONTH CONTRACT ONLY)

Western Cape
Anchor Executive Recruitment (Pty) Ltd
R10 000 - R12 000 Per Month

Property [change area]

Travel - Look, Book, Go!

Kalahari.com - shop online today

40% off top appliances!

Save 40% on the top 10 appliances on kalahari.com. While stocks last. Shop now!

Save 20% on Camping gear!

Buy 4 camping items and save 20%. While stocks last. Shop now!

Fifty Shades of Grey!

This great read will captivate you from cover to cover and leave you itching for more. Get your copy now!

20% off braai items!

Save 20% when you buy 2 braai items. While stocks last. Shop now!

30% off Pampers!

Save 30% when you buy 3 or more selected pampers products. While stocks last. Shop now!

Horoscopes
Aquarius
Aquarius

You are on form and you may like an audience to share your ideas and concepts with. Drama and creativity flavour your...read more

There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.




Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.