Trans-Pacific journey of atmospheric particles

May 2, 2017, Pacific Northwest National Laboratory
Regular dust storms are sometimes powerful enough to reach across the Pacific Ocean and dim skies over North America. This 2005 Sea-viewing Wide Field-of-view Sensor from the NASA OrbView-2 satellite detected a large dust storm over China. From April 29 until May 5, the satellite tracked the dust storm over the Pacific Ocean. Now PNNL researchers show that large dust particles can travel further than previously believed-and affect communities far from the source. Credit: Images courtesy of NASA Visible Earth: SeaWiFS images courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Puzzling skiers, occasional brownish-yellow plumes waft over Colorado ski resorts during winter and spring. Instead of wondering, researchers led by scientists at Pacific Northwest National Laboratory decided to get to the bottom of the plumes' source and content. Their research, now published in the Journal of Atmospheric Sciences found that the plumes hold countless dust particles carried from remote desert areas in Asia and Africa-dust from thousands of miles away travels to the western United States by high-altitude winds over the Pacific Ocean. The researchers also found that the atmospheric lifetime of the larger-sized dust particles is longer than expected. Climate models had always assumed the largest particles would fall out and not be transported such long distances.

Many atmospheric processes, such as long-range transport of and their removal from the atmosphere by rain and snow, largely depend on the size of the particle. Just by their size, large particles are seemingly more susceptible to this removal than smaller ones. Climate models use a simplified representation of these complex and size-dependent processes for efficiency's sake. In particular, climate model's predict that the particles with large sizes may remain suspended in the atmosphere only over relatively short distances, traveling only hundreds of miles away from their origin.

This study provides new insight into the evolution of large during their trans-Pacific voyage from Asia and Africa. The surprising conclusion is that these particles may remain suspended in the atmosphere much longer and travel for remarkably larger distances-thousands rather than hundreds of miles as the models predict. The results provide important data for scientists to fine-tune the models with the most recent understanding of atmospheric transport.

PNNL researchers teamed with collaborators from the University of Nevada, University of Wisconsin, Desert Research Institute, and National Oceanic and Atmospheric Administration to identify and characterize a major dust event at the high-elevation research sites in Colorado using an integrated, ground-based dataset of aerosol properties and sophisticated high-resolution simulations of dust evolution using a chemical transport model.

The researchers complemented their dust event characterization by analyzing the corresponding low-resolution simulations from a climate model, satellite observations, and additional ground-based measurements in Asia and the western United States. The team compared their high- and low-resolution simulations to demonstrate a better match for both the ground-based and satellite data.

The new modeling framework-with strongly linked observational and modeling components-has the potential to estimate uncertainties of climate predictions associated with transport-related processes. The team plans to apply this framework to various -important regions wherever integrated, ground-based aerosol property datasets are available.

Explore further: Well-traveled atmospheric particles, put to the test

More information: E. Kassianov et al. Large Contribution of Coarse Mode to Aerosol Microphysical and Optical Properties: Evidence from Ground-Based Observations of a Transpacific Dust Outbreak at a High-Elevation North American Site, Journal of the Atmospheric Sciences (2017). DOI: 10.1175/JAS-D-16-0256.1

Related Stories

Well-traveled atmospheric particles, put to the test

August 3, 2016

How do you test a model simulator? Compare it to real life. That's what scientists at Pacific Northwest National Laboratory did when they compared several observational sets with a simulation of how tiny atmospheric particles ...

Snow and sand erosion explained

March 3, 2017

Scientists at EPFL and SLF describe with precision how snow and sand surfaces erode when exposed to wind. Their description can contribute to better predictions of dust emissions from deserts and snow transport in Antarctica, ...

Method fills gaps in monsoon understanding

March 25, 2016

Dwindling monsoon rain is a big deal for millions in East Asia who rely on the storms for their yearly water supply. Scientists at Pacific Northwest National Laboratory uncovered some culprits most likely to have the largest ...

Recommended for you

Afromontane forests and climate change

January 17, 2019

In the world of paleoecology, little has been known about the historical record of ecosystems in the West African highlands, especially with regard to glacial cycles amidst a shifting climate and their effects on species ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.