Variations in the ability of sand particles kicked into the atmosphere from deserts in the Middle East to absorb heat can change the intensity of the Indian Summer Monsoon, according to new research from The University of Texas at Austin. The research was published July 28 in Scientific Reports, an open access journal from the publishers of Nature.

The Indian monsoon is a period of intense rainfall that more than a billion people rely on to bring rains to farmland. The results of the study could help improve monsoon prediction models, which usually use a constant value for sand particles' heat-absorbing ability. Because the absorbing ability varies greatly with region and time, assigning a constant heat-absorbing ability for the particles tends to underestimate the impact that absorbed heat can have on the monsoon system, the authors said. 

The study was led by Qinjian Jin, a postdoctoral researcher at the Massachusetts Institute of Technology, who conducted the research while earning his Ph.D. at The University of Texas at Austin's Jackson School of Geosciences. He collaborated with Zong-Liang Yang, a professor in the Jackson School's Department of Geological Sciences, and Jiangfeng Wei, a research scientist in the department.

The deserts of the Middle East are a large source of "mineral dust," small particles of sand that are brought into the atmosphere by wind and thermals. Once in the atmosphere, the dust can heat parts of the atmosphere by absorbing energy from sunlight.

The researchers found that mineral dust that originates in the Middle East can strengthen the Indian Summer Monsoon by heating the atmosphere above the Iranian Plateau and the Arabian Sea. But the dust's ability to absorb heat affected how much the dust influenced the monsoon. Dust that absorbed heat more efficiently was linked with increases in monsoon rainfall. 

"The heating ability of dust aerosols largely determines how the monsoon responds to dust," Jin said.