After analyzing the latest data provided by satellites in orbit, a team of researchers have determined that dust stirred up in the deserts of West Asia and North Africa have a causal relationship to the strengthening of the monsoons in India.
"Our analysis of global climate model simulations indicates that by heating the atmosphere, dust aerosols induce large-scale convergence over North Africa and the Arabian Peninsula, increasing the flow of moisture over India within a week," said the researchers. "According to these simulations, dust-induced heating of the atmosphere over North Africa and West Asia rapidly modulates monsoon rainfall over central India."
The latest study indicates that swirling dust to the west of India is absorbing sunlight causing the air to heat up faster. Hot air cause stronger winds carrying moisture into India. The entire process takes about a week causing stronger precipitation to occur in India.
"The difference between a monsoon flood year or a dry year is about 10 percent of the average summer rainfall in central India," said Phil Rasch, a climate scientist from the Department of Energy's (DOE) Pacific Northwest National Laboratory. "Variations driven by dust may be strong enough to explain some of that year-to-year variation."
The new findings bridges a knowledge gap in the world's weather system. Since then, the effect of dust on precipitation was previously unknown. The study was conducted by researchers from the DOE's Northwest National Laboratory and the Indian Institute of Technology Bhubaneswar in India.
The team's research demonstrates how particles in the atmosphere in one location can influence the weather system in another location. Taking the data gathered by satellites, the scientists were able to create a computer model taking into consideration the amount of dust and moisture in the entire region. The team published its findings in the online journal Nature Geoscience.
To construct a reliable timeline of these processes, the team ran simulations disregarding the effect of atmospheric dust. Without the swirling dust clouds, the simulations showed a decrease in precipitation in central India. These simulations showed that the entire process happened within the span of seven days.
While the dust played a part in the strengthening of the monsoons in India, the researchers say that the normal mechanisms surrounding the formation of monsoons are still in place.
"The strength of monsoons have been declining for the last 50 years," Rasch said. "The dust effect is unlikely to explain the systematic decline, but it may contribute."
