Featured Research

from universities, journals, and other organizations

Satellites search for 770m tons of dust in the air

Date:
September 13, 2010
Source:
University of Alabama Huntsville
Summary:
Using data from several research satellites, scientists will spend the next three years trying to understand the climate impacts of about 770 million tons of dust carried into the atmosphere every year from the Sahara.

A November 2006 NASA photograph showing dust being blown from North Africa to the Canary Islands.
Credit: NASA

Using data from several research satellites, scientists at The University of Alabama in Huntsville will spend the next three years trying to understand the climate impacts of about 770 million tons of dust carried into the atmosphere every year from the Sahara.

Some Saharan dust falls back to Earth before it leaves Africa. Some of it streams out over the Atlantic Ocean or Mediterranean Sea, carried on the wind as far away as South America and the Southeastern United States. All of it has an as-yet unmeasured impact on Earth's energy budget and the climate by reflecting sunlight back into space.

"The people who build climate models make some assumptions about dust and its impact on the climate," said Dr. Sundar Christopher, a professor of atmospheric science at UAHuntsville. "We want to learn more about the characteristics of this dust, its concentrations in the atmosphere and its impact on the global energy budget so we can replace those assumptions with real data."

Dust is one kind of particle, or aerosol, that floats around in the atmosphere. Most of the recent research into aerosols has focused on particles made by humans, such as smoke, soot or other types of pollution.

"There has been a lot of research looking at the climate effects of man-made aerosols," Christopher said. "Particles from smoke and burning fossil fuels are tiny, sub-micron size. These tiny particles cool the atmosphere because they reflect sunlight back into space before it has a chance to heat the air. That means less solar energy is available at the surface to heat the planet."

Because they are so small, pollution aerosols don't have a significant effect on heat energy. That's why they usually have a net cooling effect on the atmosphere.

Dust particles, on the other hand, weighing in at a hefty 10+ microns (a human hair is about 100 microns in diameter) do absorb some solar radiation, convert it to heat and release that heat into the air. They also reflect some radiation back into space, so dust both heats and cools the atmosphere.

More importantly they have a significant effect on heat energy in the air. Dust absorbs thermal energy rising from the ground and re-radiates it either toward space (and colder temperatures) or back toward the surface.

"One thing we want to do is calculate how reflective dust is, because not all dust is created equal," Christopher said. "We're trying to calculate reflectivity so we can say with precision how much sunlight is being reflected."

The composition and shape of dust particles is very complex. They are not spherical, which makes calculating their energy budget challenging and time consuming. Also, the composition of dust varies depending on which part of the Sahara the dust comes from. Some of it absorbs more solar energy than others.

"Climate models are not very sophisticated in the way they handle dust," Christopher said. "And the long-wave or infrared part is something that has been ignored for a long time. We want to nail down those values."

Why start with the Sahara? First, the Sahara contributes about half of all of the dust carried into Earth's atmosphere every year. The Saharan dust is also more "pristine" than dust from U.S. or Asian deserts. Dust from U.S., Chinese or Mongolian deserts frequently mixes with pollution to create an aerosol stew, which can make it difficult to study just the dust.

Studying the Saharan dust is enough of a challenge, in part because it is made of the same stuff as the desert underneath. That means the dust in the atmosphere looks very much like the surface below it. Only in the past few years have new instruments and new techniques been developed that help scientists "see" which is dust and which is desert.

Christopher has received a grant of almost $500,000 through NASA's CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) program to support the research for the next three years. The CALIPSO satellite's instruments include a LIDAR, which shoots a laser into the atmosphere then catches light that bounces off particles in the air to learn more about aerosols.


Story Source:

The above story is based on materials provided by University of Alabama Huntsville. Note: Materials may be edited for content and length.


Cite This Page:

University of Alabama Huntsville. "Satellites search for 770m tons of dust in the air." ScienceDaily. ScienceDaily, 13 September 2010. <www.sciencedaily.com/releases/2010/09/100913163209.htm>.
University of Alabama Huntsville. (2010, September 13). Satellites search for 770m tons of dust in the air. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2010/09/100913163209.htm
University of Alabama Huntsville. "Satellites search for 770m tons of dust in the air." ScienceDaily. www.sciencedaily.com/releases/2010/09/100913163209.htm (accessed September 2, 2014).

Share This




More Earth & Climate News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Thousands of Fish Dead in Mexico Lake

Raw: Thousands of Fish Dead in Mexico Lake

AP (Sep. 2, 2014) — Over 53 tons of rotting fish have been removed from Lake Cajititlan in western Jalisco state. Authorities say that the thousands of fish did not die of natural causes. (Sep. 2) Video provided by AP
Powered by NewsLook.com
Raw: Iceland Volcano Spewing Smoke

Raw: Iceland Volcano Spewing Smoke

AP (Sep. 2, 2014) — The alert warning for the area surrounding Iceland's Bardarbunga volcano was kept at orange on Tuesday, indicating increased unrest with greater potential for an eruption. Smoke is spewing from the volcano, and lava is spouting nearby. (Sept. 2) Video provided by AP
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Halliburton Reaches $1B Gulf Spill Settlement

Halliburton Reaches $1B Gulf Spill Settlement

AP (Sep. 2, 2014) — Halliburton's agreement to pay more than $1 billion to settle numerous claims involving the 2010 BP oil spill could be a way to diminish years of costly litigation. A federal judge still has to approve the settlement. (Sept. 2) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins