[meteorite-list] Around the World in Four Days: NASA Tracks Chelyabinsk Meteor Plume

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 14 Aug 2013 12:11:28 -0700 (PDT)
Message-ID: <201308141911.r7EJBSFX014408_at_zagami.jpl.nasa.gov>

http://www.nasa.gov/content/goddard/around-the-world-in-4-days-nasa-tracks-chelyabinsk-meteor-plume/

Around the World in Four Days: NASA Tracks Chelyabinsk Meteor Plume
Kathryn Hansen
NASA's Earth Science News Team
Aug. 14, 2013

[Video]
A meteor weighing 10,000 metric tons exploded 14 miles above Chelyabinsk,
Russia, on Feb. 15, 2013. Unlike similar past events, this time scientists
had the sensitive instruments on the Suomi NPP satellite to deliver unprecedented
data and help them track and study the meteor plume for months.

Atmospheric physicist Nick Gorkavyi missed witnessing an event of the
century last winter when a meteor exploded over his hometown of Chelyabinsk,
Russia. From Greenbelt, Md., however, NASA's Gorkavyi and colleagues witnessed
a never-before-seen view of the atmospheric aftermath of the explosion.

Shortly after dawn on Feb. 15, 2013, the meteor, or bolide, measuring
59 feet (18 meters) across and weighing 11,000 metric tons, screamed
into Earth's atmosphere at 41,600 mph (18.6 kilometers per second). Burning
from the friction with Earth's thin air, the space rock exploded 14.5
miles (23.3 kilometers) above Chelyabinsk.

The explosion released more than 30 times the energy from the atom bomb
that destroyed Hiroshima. For comparison, the ground-impacting meteor
that triggered mass extinctions, including the dinosaurs, measured about
6 miles (10 kilometers) across and released about 1 billion times the
energy of the atom bomb.

Some of the surviving pieces of the Chelyabinsk bolide fell to the ground.
But the explosion also deposited hundreds of tons of dust up in the stratosphere,
allowing a NASA satellite to make unprecedented measurements of how the
material formed a thin but cohesive and persistent stratospheric dust
belt.

"We wanted to know if our satellite could detect the meteor dust," said
Gorkavyi, of NASA's Goddard Space Flight Center in Greenbelt, Md., who
led the study, which has been accepted for publication in the journal
Geophysical Research Letters. "Indeed, we saw the formation of a new dust
belt in Earth's stratosphere, and achieved the first space-based observation
of the long-term evolution of a bolide plume."

Gorkavyi and colleagues combined a series of satellite measurements with
atmospheric models to simulate how the plume from the bolide explosion
evolved as the stratospheric jet stream carried it around the Northern
Hemisphere.

About 3.5 hours after the initial explosion, the Ozone Mapping Profiling
Suite instrument's Limb Profiler on the NASA-NOAA Suomi National Polar-orbiting
Partnership satellite detected the plume high in the atmosphere at an
altitude of about 25 miles (40 kilometers), quickly moving east at about
190 mph (more than 300 kph).

The day after the explosion, the satellite detected the plume continuing
its eastward flow in the jet and reaching the Aleutian Islands. Larger,
heavier particles began to lose altitude and speed, while their smaller,
lighter counterparts stayed aloft and retained speed - consistent with
wind speed variations at the different altitudes.

By Feb. 19, four days after the explosion, the faster, higher portion
of the plume had snaked its way entirely around the Northern Hemisphere
and back to Chelyabinsk. But the plume's evolution continued: At least
three months later, a detectable belt of bolide dust persisted around
the planet.

The scientists' model simulations, based on the initial Suomi NPP observations
and knowledge about stratospheric circulation, confirmed the observed
evolution of the plume, showing agreement in location and vertical structure.

"Thirty years ago, we could only state that the plume was embedded in
the stratospheric jet stream," said Paul Newman, chief scientist for Goddard's
Atmospheric Science Lab. "Today, our models allow us to precisely trace
the bolide and understand its evolution as it moves around the globe."

The full implications of the study remain to be seen. Every day, about
30 metric tons of small material from space encounters Earth and is suspended
high in the atmosphere. Even with the addition of the Chelyabinsk debris,
the environment there remains relatively clean. Particles are small and
sparse, in contrast to a stratospheric layer just below where abundant
natural aerosols from volcanoes and other sources collect.

Still, with satellite technology now capable of more precisely measuring
tiny atmospheric particles, scientists can embark on new studies in high-altitude
atmospheric physics. How common are previously unobservable bolide events?
How might this debris influence stratospheric and mesospheric clouds?

Scientists previously knew that debris from an exploded bolide could make
it high into the atmosphere. In 2004, scientists on the ground in Antarctica
made a single lidar observation of the plume from a 1,000-ton bolide.

"But now in the space age, with all of this technology, we can achieve
a very different level of understanding of injection and evolution of
meteor dust in atmosphere," Gorkavyi said. "Of course, the Chelyabinsk
bolide is much smaller than the 'dinosaurs killer,' and this is good:
We have the unique opportunity to safely study a potentially very dangerous
type of event."
Received on Wed 14 Aug 2013 03:11:28 PM PDT