Unexpected Teleconnections in Noctilucent Clouds
 
April 16, 2014: Earth's poles are separated by four oceans, six continents and
more than 12,000 nautical miles.
 
Turns out, that's not so far apart.
 
New data from NASA's AIM spacecraft have revealed "teleconnections" in Earth's
atmosphere that stretch all the way from the North Pole to the South Pole and
back again, linking weather and climate more closely than simple geography
would suggest.
 
http://www.youtube.com/watch?v=7d3t1_l4bcw
 
A new ScienceCast video explores unexpected "teleconnections" in Earth's
atmosphere that link weather and climate across vast distances.  Play it
 
For example, says Cora Randall, AIM science team member and Chair of the Dept.
of Atmospheric and Oceanic Sciences at the University of Colorado, "we have
found that the winter air temperature in Indianapolis, Indiana, is well
correlated with the frequency of noctilucent clouds over Antarctica."
 
Noctilucent clouds, or "NLCs," are Earth's highest clouds.  They form at the
edge of space 83 km above our planet's polar regions in a layer of the
atmosphere called the mesosphere.  Seeded by "meteor smoke," NLCs are made of
tiny ice crystals that glow electric blue when sunlight lances through their
cloud-tops.
 
AIM was launched in 2007 to investigate these "night-shining" clouds, to
discover how they form and to learn about their inner chemistry.  As is often
the case, however, when exploring the unknown, researchers found something
they weren't even looking for: teleconnections.
 
"It has been a surprise," says Hampton University professor of atmospheric and
planetary science James Russell, Principal Investigator of the AIM mission.
"Years ago when we were planning the AIM mission, our attention was focused on
a narrow layer of the atmosphere where NLCs form.  Now we are finding out this
layer manifests evidence of long-distance connections in the atmosphere far
from the NLCs themselves."
 
One of these teleconnections links the Arctic stratosphere with the Antarctic
mesosphere.
 
"Stratospheric winds over the Arctic control circulation in the mesosphere,"
explains Randall. "When northern stratospheric winds slow down, a ripple
effect around the globe causes the southern mesosphere to become warmer and
drier, leading to fewer NLCs. When northern winds pick up again, the southern
mesosphere becomes colder and wetter, and the NLCs return."
 
http://science.nasa.gov/media/medialibrary/2014/04/16/correlation.jpg
 
The winter air temperature in Indianapolis is correlated with the frequency of
noctilucent clouds over Antarctica.
 
This January, a time of year when southern NLCs are usually abundant, the AIM
spacecraft observed a sudden and unexpected decline in the clouds.
Interestingly, about two weeks earlier, winds in the Arctic stratosphere were
strongly perturbed, leading to a distorted polar vortex.
 
"We believe that this triggered a ripple effect that led to a decline in
noctilucent clouds half-way around the world," says Laura Holt of the
University of Colorado's Laboratory for Atmospheric and Space Physics. "This
is the same polar vortex that made headlines this winter when parts of the USA
experienced crippling cold and ice."
 
Holt took a careful look at meteorological data and found that, indeed, there
was a statistical link between winter weather in the USA and the decline in
noctilucent clouds over Antarctica.
 
"We picked Indianapolis as an example, because I have family living there,"
says Randall, "but the same was true of many northern cities: cold air
temperatures on the ground were correlated with NLC frequencies high above
Antarctica two weeks later," she says.
 
The two week delay is, apparently, how much time it takes for the
teleconnection signal to propagate through three layers of atmosphere (the
troposphere, stratosphere and mesosphere), and from pole to pole.
 
It is a complicated topic, but this much is clear: "NLCs are a valuable
resource for studying long-distance connections in the atmosphere," says
Russell, "and we are just getting started."
 
Credits:
Author: Dr. Tony Phillips |  Production editor: Dr. Tony Phillips | Credit:
Science@NASA
 
More information:
 
Electric-Blue Clouds Appear over Antarctica -- Science@NASA
 
Meteor Smoke Makes Strange Clouds -- Science@NASA
 
Strange Clouds at the Edge of Space -- Science@NASA
 
 
Regards,
 
Roger

--- D'Bridge 3.99
 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)