"The plume from the shuttle becomes a ready-made experiment to observe the movement in the atmosphere," says Charles Jackman, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. who is the project scientist for a NASA mission called Aeronomy Ice in the Mesosphere (AIM) that specifically observes PMCs. "What this team found is interesting since the plume moved so quickly to the pole, indicating that the winds appear much stronger at those latitudes than was thought."
To track the plume across the sky, the scientists collated seven sets of observations, including data from AIM. The first two sets of instruments to see the plume were on a NASA spacecraft called TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics). Next the plume was viewed through the Sub-Millimeter Radiometer on the Swedish Odin satellite. When the plume reached higher latitudes, it was picked up by the ground-based Microwave Spectrometer at the Institute of Atmospheric Physics in Khlungsborn, Germany as well as an identical ground-based water vapor instrument called cWASPAM1 at the Arctic Lidar Observatory for Middle Atmospheric Research (ALOMAR) in Andenes, Norway. The plume collated into its final shape over the arctic, as a new, extremely bright PMC on July 9, 2011 and there, it could be observed from above by the AIM satellite flying overhead, and from below by another instrument at ALOMAR called the RMR lidar.
Over the course of the plume's travels, these observations showed it spreading horizontally over a distance of some 2000 to 2500 miles. Those parts that drifted into the high latitudes near the North Pole formed ice particles which settled into layers of PMCs down at about 55 miles above Earth's surface. The speed with which the plume arrived at the arctic was a surprise.
"The speed of the movement in the upper atm
|Contact: Susan Hendrix|
NASA/Goddard Space Flight Center