Guides for space weather abbreviations in advisories and space weather advisories for pilots available

Aviation space weather advisories Quick reference guide to space-weather specific abbreviations and User’s guide to Space Weather Advisories for Pilots are now available in PECASUS dissemination section.

Impact of Space Weather on Aviation

The Sun drives our planet’s weather and climate patterns. The exposure of regions on Earth to sunlight is a key component in weather & climate, and changes on a daily and seasonal basis. Solar energy is pumped into our atmosphere and drives the weather, potentially causing storms.Similar to this, we have space weather and space climate. Besides sunlight entering our atmosphere, there is also solar mass continuously flowing along the magnetic shield surrounding Earth. Our atmosphere and magnetosphere can respond in a dramatic way to an abrupt change in the continuous emittance of light and mass from the Sun. A solar storm initiates space weather processes which impact our navigation and radio communication systems and can cause an increase of radiation levels at flight altitude.

Space Weather Warnings for Aviation

PECASUS advises pilots in case Space Weather (SWX) causes a moderate or severe impact on the radiation at flight level, Satellite navigation or long distance Radio communication.PECASUS continuously monitors and measures the atmospheric and magnetospheric space weather parameters. When there is an indication that the health of passengers and crew might be affected due to radiation, or when the HF communication or satellite navigation is impacted, an advisory message is sent out through the standard communication networks defined by the International Civil Aviation Organization (ICAO). The advisories have a standard format.

Radiation at flight level

During solar storms, solar particles like protons can suddenly be accelerated, heading into space at great speed. When they arrive at Earth, these energetic particles can penetrate the atmosphere at the magnetic poles. They bombard atmospheric particles and create a shower of particles possibly reaching the Earth’s surface. When this happens, crew and passengers onboard airplanes are more vulnerable to this harmful radiation. The effect is stronger at high altitudes and latitudes.

Satellite navigation

The ionosphere plays also a crucial role in satellite navigation. The signal sent by the satellite has to pass through the ionosphere to reach the receiver. Solar storms can introduce small scale structures in the ionosphere. When the signal encounters these obstacles, its amplitude and phase can alter very rapidly. Similarly, when the number of electrons in the ionosphere increases dramatically due to a solar storm, positioning errors are introduced in satellite navigation.

HF communication

The ionosphere is a layer at the top of our atmosphere which is ionised due to sunlight (at ultraviolet and x-ray wavelengths). Because the layer is ionised, it has the ability to reflect HF radio waves allowing long distance radio communication, which is crucial for aviation. HF radio waves have frequencies between 3 and 30 MHz.However, during solar storms, extra energy is deposited into the ionosphere, introducing additional ionisation and irregularities. HF radio waves can be absorbed or reflected in unforeseen ways, causing a radio communication failure. This malfunctioning can happen near the Earth’s poles or on the day-light side of the Earth, depending on the sort of solar storm and associated energy input.

Harri Haukka