The National Aeronautics and Space Administration (NASA) is set to launch the Atmospheric Waves Experiment (AWE) to study one of the important drivers of Space weather – the Earth’s weather.
- AWE is a first-of-its-kind NASA experimental attempt aimed at studying the interactions between terrestrial and Space weather.
- It is planned under NASA’s Heliophysics Explorers Program.
- The mission will study the links between how waves in the lower layers of the atmosphere impact the upper atmosphere, and thus, Space weather.
- It will look down at the Earth and record the colourful light bands, commonly known as airglow.
- The new NASA mission will try to understand the combination of forces that drive the Space weather in the upper atmosphere.
- AWE will measure the airglow at mesopause (about 85 to 87 km above the Earth’s surface), where the atmospheric temperatures dip to minus 100 degrees Celsius.
- At this altitude, it is possible to capture the faint airglow in the infrared bandwidth, which appears the brightest enabling easy detection.
Space weather
- Apart from influences from the Sun-bound emissions, Space weather also comes under the impact of terrestrial weather.
- In the atmosphere, there are a wide variety of waves, travelling both horizontally and vertically. Atmospheric Gravity Waves (AGW) are one such kind of vertical wave.
- They are mostly generated when there is an extreme weather event or a sudden disturbance leading to a vertical displacement of stable air.
- Natural phenomena like thunderstorms, hurricanes, tornadoes, regional orography and others have the potential to send out a variety of periodic waves, including AGWs, in the lower levels of the atmosphere.
- A stable atmosphere plays an important role in the generation of gravity waves, that is, when the atmosphere is stable, the temperature difference between the rising air and the atmosphere produces a force that pushes this air to its original position.
- The air will continuously rise and sink, thus creating a wave-like pattern.
- AGW is a wave that moves through a stable layer of the atmosphere, wherein the upward-moving region is the most favourable for the formation of cloud patterns or streaks.
- AGWs continue all the way to Space, where they contribute to the Space weather.
Mesosphere and mesopause
- The mesosphere is a layer of Earth’s atmosphere. The mesosphere is directly above the stratosphere and below the thermosphere.
- It extends from about 50 to 85 km (31 to 53 miles) above our planet. Temperature decreases with height throughout the mesosphere.
- The coldest temperatures in Earth’s atmosphere, about -90° C (-130° F), are found near the top of this layer. The boundary between the mesosphere and the thermosphere is called the mesopause.
- At the bottom of the mesosphere is the stratopause, the boundary between the mesosphere and the stratosphere.
- Weather balloons and other aircraft cannot fly high enough to reach the mesosphere. Satellites orbit above the mesosphere and cannot directly measure the traits of this layer.
Differences between airglow and auroras
- Though they appear at similar altitudes, aurora and airglow are produced by different physical processes.
- Nighttime airglow (or nightglow) is a type of chemiluminescence—the emission of light from chemical interactions between oxygen, nitrogen, and other molecules in the upper atmosphere.
- Airglow occurs all around the Earth, all the time. However, nightglow is much easier to spot over a dark Earth than dayglow, as airglow is just one billionth as bright as the Sun.
- Auroras, on the other hand, stem from interactions between solar energy and Earth’s magnetic field.
- The magnetic field funnels the energy into the upper atmosphere, where it interacts with the same atoms as airglow (mainly oxygen and nitrogen).
This is why both phenomena can produce similar colors.
The dynamic nature of Earth’s magnetic field moves the solar energy in irregular ways, causing each aurora event to be visually unique.
