WASHINGTON.—Asian desert dust and city pollution is swirling
in vast plumes across the Pacific to North America, interacting with storms and
possibly spurring climate change, an airborne scientist said on Tuesday.
Jeff Stith of the National Center for Atmospheric Research
communicated with reporters via Web chat from a research jet flying 40,000 feet
above the ocean as part of a mission to track dust and pollution particles blown
from Asia to the United States.
"We have found enhancements in pollution levels in some of
the upper regions of the storm clouds we studied, just yesterday for example,"
Stith wrote.
Stith and his ground-based colleague, V. Ramanathan of the
Scripps Institution of Oceanography, aimed to study the interaction between the
pollution and dust with high-altitude clouds bearing ice crystals.
Ice crystals are found in extremely cold clouds, and when the
crystals are composed entirely of frozen water, they reflect lots of sunlight –
that’s why these clouds look so white, Ramanathan said by telephone after the
Web chat.
However, if particles of dust and a dark pollutant known as
black carbon managed to get inside the crystals, these clouds might absorb more
solar energy rather than reflecting it all, Ramanathan said.
The high-flying jet, a specially equipped Gulfstream V, has a
range of 6,000 miles and is needed to monitor the dust plumes, which speed
across the ocean and occur every few days, the scientists said.
"We are finding that the entire Pacific Ocean is just a hop,
skip and a jump away from North America; the dust and pollution plumes are
traveling fast and Hiaper (the scientists’ name for the plane) is able to keep
up with the plume," Ramanathan wrote in the Web chat.
The plane’s sophisticated instruments monitor the dust and
pollution, but it is also visible to scientists traveling through it, Stith
wrote.
"The dust itself will be yellowish in color; but when it is
mixed with BC (black carbon) it gets brownish; Normally when you are above the
dust layer and you look at the sky sideways it will be brown in color," Stith
wrote.
The plume begins forming when dust is lifted from the
Mongolian and Taklamakan deserts, according to Stith. When it passes over East
Asia, it picks up aerosol particles from burning fossil fuels, cooking fires and
other fires where biomass goes up in flames.
The experiment only tracks the plumes as they travel across
the Pacific but Ramanathan said high-altitude pollution – above 1.9 miles –
should be able to travel across North America and out over the Atlantic Ocean.
"This is why dust and soot getting into the higher layers is so important,"
Ramanathan wrote. "This is what makes a local (problem) into a global problem."
