Solar Storms & Ionospheric Activity Print E-mail

Weathering the Storm

Solar FlareThe next 5 years will see an increase in solar activity and ionospheric noise. VRS solutions have advanced real-time ionospheric correction modeling which significantly reduce errors at the rover due to Solar Wind.

Space Weather

A GNSS  receiver uses radio signals from several orbiting satellites to determine the range, or distance, from each satellite, and determines from these ranges the actual position of the receiver. The radio signals must pass through the ionosphere and in so doing they are subjected to variations in the electron density structure of the ionosphere. Changes in the electron density due to space weather activity can change the speed at which the radio waves travel, introducing a “propagation delay“ in the GPS signal. The propagation delay can vary from minute to minute, and such intervals of rapid change can last for several hours, especially in the polar and auroral regions. Changing propagation delays cause errors in the determination of the range, or “range errors“.

When charged particles ejected from the Sun arrive at the Earth, they can cause perturbations in the geomagnetic field. Another effect is that in the ionosphere the electron density (number of electrons in a given volume) can vary considerably, both in time and space.

Space Weather refers to a collection of physical processes, beginning at the Sun and ultimately affecting human activities on Earth and in space. The Sun emits flares of electromagnetic radiation and as energetic electrically charged particles through coronal mass ejections and plasma streams. The particles travel outwards as the solar wind, carrying parts of the Sun's magnetic field with them. The electromagnetic radiation travels at the speed of light and takes about 8 minutes to move from Sun to Earth, whereas the charged particles travel more slowly, taking from a few hours to several days to move from Sun to Earth. The radiation and particles interact with the Earth's (geo)magnetic field and outer atmosphere in complex ways, causing concentrations of energetic particles to collect and electric currents to flow in regions of the outer atmosphere (magnetosphere and ionosphere). These can result in geomagnetic variations, aurora, and can affect a number of technologies including GNSS positioning.

I95 Index

The Index 95 values reflect the intensity of ionospheric activity, i.e., the expected influences onto the relative GPS positions. The I95 values are computed from the ionospheric corrections for all satellites at all network stations for the respective hour. The worst 5% of data are rejected. The highest then remaining value is the I95 index value that is displayed at the graph.

Space Weather Prediction Center NOAA USA
http://www.swpc.noaa.gov/SWN/index.html

Space Weather Canada   NRC
For current space weather information for the ISES Regional Warning Centre for Canada goto
http://www.spaceweather.gc.ca/index_e.php