The polar jet is an atmospheric circulation that is capable of transporting dust and warm, moist air from subtropics and mid-latitudes to the Arctic. This is a severe concern because roughly half of the warming in the Arctic is now being placed on higher levels of moisture and heat transported to the region from elsewhere.
Researchers at NYU Abu Dhabi recently reported that this meandering polar jet stream is depositing not only warm, moist air, but also hot dust from the Sahara Desert to the Arctic Circle. They collected data that shows that as a result of this deposit of warm dust, southeastern Greenland experienced higher surface temperatures (a 10-degree Celsius rise) for over three consecutive days. Such heightened temperatures greatly impacted ice melt in the region, which is already under great stress from climate change.
"The polar jet stream has been identified as the main driver for such events leading to the transport of large amounts of dust to high-latitudes," said Diana Francis, the lead researcher on this study. "If the polar jet is set to slow more frequently due to the changes in the Arctic climate system and to the Arctic Amplification, such events are expected to become more frequent."
The study was initiated in part because of a 2011 cyclone over Morocco that transported 38 million ton of dust, depositing 1.3 million tons of it in the Arctic. From this research, the scientists were able to determine that this meandering polar jet has the largest capability to transport dust because of its geographic location and close proximity to the pole. This means that dust is able to travel 4,000km over just three or four days.
“Before, many studies pointed out pathways through Europe or through the Atlantic around the Bermuda High, very long pathways where most of the dust settles in the ocean or over Europe on its way to the Arctic,” said Francis. “But this pathway is very short and reaches the Arctic in a few days, which means most of the dust is directly injected in the Arctic.”
The scientists urge that more research is needed in order to understand the atmospheric circulation of the polar jet. "The impact of dust deposition on ice in Greenland, such as darkening ice and formation of algae on ice or cryoconite, as well as the link between Saharan dust transport and the Arctic heat dome must be investigated further in collaboration with scientists in UK and Germany," Francis stressed. With such research, better models could be made projecting sea level rise and global temperature changes. The study was published in the Journal of Geophysical Research: Atmospheres.