A new satellite will explore how the weather “down here” in the troposphere affects the weather “up there” in the ionosphere, from 30 miles above ground to 600 miles. Everything above 100 miles is classed as space, so this includes most of the ionosphere.
The Ionospheric Connection Explorer or Icon is being built by UC Berkeley for Nasa to investigate the upward coupling effect, the mysterious way that storm systems affect conditions at much higher altitudes.
In the ionosphere, weather is mainly a matter of plasma – streams of charged particles. In a daily cycle, ultraviolet light from the sun ionises air in the daytime, creating plasma, which recombines at night. The plasma is sometimes visible as a swathe of colour known as airglow. Around sunset there are regularly huge upwellings of ionised gas called plasma fountains.
In theory, the only disturbance to the ionosphere’s daily rhythm should come from solar storms, flares and coronal mass ejections. However, even when the sun is calm, the ionosphere can experience turbulent conditions. These may disrupt radio communications or even damage satellites. It now seems that jets, sprites and other exotic forms of lightning may contribute to these effects in the ionosphere far above.
Icon will make the first full survey of plasma below 300 miles, helping researchers understand how weather affects the ionosphere. This might lead to a space weather forecast, warning satellite operators when to shift to a higher orbit to avoid oncoming storms.
