Scientists can, therefore, use the region as a sensitive 'litmus paper' for detecting global change. The ionosphere, which is a layer within the thermosphere, is one of the least explored and least understood parts of the Earth's atmosphere. Since 1958 BAS researchers have monitored changes in the upper atmosphere by using the ionosphere as a 'tracer'. Radio wave pulses are bounced off the ionosphere from study sites on the Antarctic Peninsula and the Falkland Islands. This latest discovery was made from analysis of over 600,000 film records of echo-sounding signatures collected by scientists from BAS and the Rutherford Appleton Laboratory.
Atmospheric pressure controls the altitude of the ionosphere.
As the thermosphere cools, the pressure drops, consequently lowering the level of the ionosphere. The ionosphere is, in effect, the Earth's high altitude barometer. It is, however, another warning signal about what changes to the atmosphere can be caused by human impact. Measurements taken by our European colleagues suggested there may be a drop in altitude but these results from Antarctica confirm that it is indeed a global effect. We know that the thermosphere provides an ideal place to study global changes.