The Canadian High Arctic Ionospheric Network (CHAIN) is an array of ground-based radio instruments deployed in the

Canadian Arctic Northern Canada (), colloquially the North or the Territories, is the vast northernmost region of Canada, variously defined by geography and politics. Politically, the term refers to the three territories of Canada: Yukon, Northwest Territories a ...

and operated by the

University of New Brunswick The University of New Brunswick (UNB) is a public university with two primary campuses in Fredericton and Saint John, New Brunswick. It is the oldest English language, English-language university in Canada, and among the oldest public universiti ...

. The CHAIN instruments include high data-rate

GPS The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...

receivers and digital ionosondes. After passing through the Earth's

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...

microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...

GPS signals carry information about the

total electron content Total electron content (TEC) is an important descriptive quantity for the ionosphere of the Earth. TEC is the total number of electrons integrated between two points, along a tube of one meter squared cross section, i.e., the electron columnar ...

(TEC). This information is commonly used to improve the precision of

and to study ionospheric morphology. Ionosondes transmit pulses of radio signals in the

Medium Frequency Medium frequency (MF) is the International Telecommunication Union, ITU designation for Radio frequency, radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) A ...

(MF) and

High Frequency High frequency (HF) is the ITU designation for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one ...

(HF) ranges, whose echos are analyzed to measure height and density of the ionosphere. Advanced digital ionosondes used in the CHAIN network are also able to measure the bulk motion of ionospheric plasma. Most of the CHAIN instruments are located within the polar cap defined as a region of open

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

lines. The polar cap

is directly linked to the

interplanetary magnetic field The interplanetary magnetic field (IMF), also commonly referred to as the heliospheric magnetic field (HMF), is the component of the solar magnetic field that is dragged out from the solar corona by the solar wind flow to fill the Solar System ...

carried by the

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

. Polar cap thus provides a vantage point for the study of energy exchange between the

magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...

and

. CHAIN is an integral part of the Canadian Geospace Monitoring (CGSM) programme. It provides ground support for Canadian and international scientific space missions such as

THEMIS In Greek mythology and religion, Themis (; ) is the goddess and personification of justice, divine order, law, and custom. She is one of the twelve Titan children of Gaia and Uranus, and the second wife of Zeus. She is associated with oracles a ...

and

CASSIOPE ''Cassiope'' is a genus of 18 small shrubby species in the family Ericaceae. It is the sole genus in the subfamily Cassiopoideae. They are native to the Arctic and north temperate montane regions. The genus is named after Cassiopeia of Greek ...

. CHAIN ionosonde and GPS data are used for tomographic reconstructions of polar cap plasma anomalies during geomagnetic storms In January 2012, the Canada Foundation for Innovation announced funding for the Expanded Canadian High-Arctic Ionospheric Network (ECHAIN). This funding was used to add 15 Global Positioning System (GPS) receivers to the existing network of GPS receivers and radars of the Canadian High Arctic Ionospheric Network (CHAIN). The data will contribute significantly to the progress of space research by providing a better understanding of the processes in the Sun-Earth system.

CHAIN instrument sites

References

External links