18 November 2019
Polar winds stir desert dust
Published online 30 August 2019
Severe dust storms over the Middle East have been traced back to atmospheric events at the top of the world.
In September 2015 severe dust storms emerged over the Middle East and Arabian Peninsula. The dust storms involved a rain-free ‘dry cyclone’ event, the type of which had not been previously reported in the region. Researchers believe they have traced the origin of this unusual event back to changes in the circulation of a belt of high-level winds in the northern polar region called the polar jet.
“Everything in the Earth’s climate system is connected. Our study shows that changes near the North Pole can cause severe weather events in the Middle East,” says atmospheric scientist Diana Francis of New York University Abu Dhabi in the United Arab Emirates.
Warming in the northern polar region appears to be causing changes in the polar jet circulation, she explains.
The analysis was based on a variety of ground observations and satellite data. The evidence suggests that a southward movement of the polar jet was the main driver of the large dry cyclone that developed over Iraq on 31 August 2015. This generated intense dust storms over most countries of the Arabian Gulf through early September. The cyclone in Iraq was traced back to events in the atmosphere over Turkey one day earlier, and ultimately to more distant changes in the polar jet shortly beforehand.
"By drawing on a wide variety of observational sources, this study paints a fairly comprehensive picture of the evolution of the events from start to finish," comments meteorology researcher Earle Williams of the Massachusetts Institute of Technology, USA, who was not involved in the study.
The researchers point out that the transport of mineral dust in the atmosphere affects the Earth’s climate and agriculture in regions far from the origins of the dust. Studying the processes involved will help elucidate existing atmospheric patterns as well as the potential impact of climate change.
Francis, D. K. et al. Cyclogenesis and density currents in the Middle East and the associated dust activity in September 2015. Geosciences https://doi.org/10.3390/geosciences9090376 (2019).