A satellite image shows the accumulation of smoke in the atmosphere from fires burning in western Africa. Photo by NASA Earth Observatory/Joshua Stevens/VIIRS data/Suomi NPP
GREENBELT, Md., Jan. 10 (UPI) -- Researchers have identified a unique link between fire and drought in Africa. Previous studies have shown the role drought plays in bolstering the risk of wildfire, but the latest research does the opposite.
NASA scientists found a link between wildfire and controlled burning in northern sub-Saharan Africa and the region's water cycle.
"We wanted to look at the general impacts of burning on the whole spectrum of the water cycle," Charles Ichoku, a senior scientist at NASA's Goddard Space Flight Center, said in a news release.
Researchers examined satellite data collected by NASA's Moderate Resolution Imaging Spectroradiometer and the Tropical Rainfall Measurement Mission between 2001 and 2014. Through data analysis, they were able to tease out a relationship between fire activity and hydrological indicators, including soil moisture, precipitation, evapotranspiration and vegetation greenness -- all factors that help trigger rain.
"There is a tendency for the net influence of fire to suppress precipitation in northern sub-Saharan Africa," Ichoku concluded.
Aerosols -- smoke, dust and other particulates suspended in the atmosphere -- can serve as cloud-forming nuclei, which can encourage rain clouds and precipitation. But an abundance of aerosols in the atmosphere can also disperse water vapor, making it less likely clouds will materialize.
The new research -- published in the journal Environmental Research Letters -- fails to forge a direct link between fire and rain. The correlation is between fire and water cycle indicators only. But scientists are improving climate models using the data discovered in their latest research, and may soon be able to show a more conclusive link between fire and precipitation.
Scientists hope their new and improved models can help them explain a few of the paradoxical findings turned up during their latest research efforts. Scientists want to know why, for example, precipitation didn't increase between 2006 and 2013 as fire activity decreased.
Researchers believe changes in the types of land being burned may have something to do with the anomaly.
"The removal of vegetal cover through burning would likely increase water runoff when it rains, potentially reducing their water retention capacity and invariably the soil moisture," Ichoku said. "The resulting farming would likely deplete rather than conserve the residual moisture, and in some cases, may even require irrigation. Therefore, such land cover conversions can potentially exacerbate the drought."