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   
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