geomagnetic storms

geomagnetic storms

All the geomagnetic storms are disturbances in the Earth's magnetic field that last from a few hours to days. Their origin is external and they result from a sudden increase in particles emitted by solar flares that reach the magnetosphere, creating changes in the Earth's magnetic field. Geomagnetic storms are global in nature and start at all points on Earth at the same time. However, the magnitude of observed storms varies from place to place, and the higher the latitude, the greater the magnitude.

In this article we are going to tell you what geomagnetic storms are, what their characteristics and danger are.

Formation of geomagnetic storms

geomagnetic storms in space

The occurrence of geomagnetic storms is related to solar activity. The sun is constantly emitting particles in what is called the "solar wind." These particles usually do not penetrate the Earth's atmosphere because they are deflected by the Earth's magnetosphere.

However, the Sun does not have a constant activity, but rather exhibits activity that varies over a duration of 11 years, in the so-called "solar cycle", which is quantified by the number of sunspots it sees in each period. moment. . During this 11-year cycle, the Sun has varied from minimal activity with nearly disappearing sunspots to maximal activity with a significant increase in sunspot number.

Sunspots correspond to regions cooler in the sun's photosphere where the magnetic field is very strong and are considered active regions of the sun. It is in these sunspots that solar flares and coronal mass ejections (CMEs) are created. ) Corresponds to a violent eruption that throws large amounts of coronal material into the interplanetary medium, thus modifying the density of the solar wind and its speed.

When CMEs are large enough and occur in Earth's direction, the increased density and speed of the solar wind can warp Earth's magnetosphere, creating geomagnetic storms. These affect the entire planet at the same time, and depending on how fast the solar wind reaches violently expelling, they can take a day or a few days to occur, since this phenomenon occurs on the Sun.

In recent years, a number of satellite missions have been launched into space to monitor the activity of the sun from different locations and to be able to warn of coronal mass ejections that could affect the Earth.

How to measure geomagnetic storms?

telecommunications damage

A geomagnetic storm is recorded at geomagnetic observatories as a fairly sudden disturbance that affects components of the Earth's magnetic field and persists for a day or more until calm is restored.

to quantify For the magnitude of geomagnetic storms, the Geomagnetic Index was used. Of these, the most widely used are the Dst index, which represents the magnetic activity of a network of four geomagnetic observatories located near the magnetic equator, and the three-hour index, which represents the activity

Geomagnetism is performed every three hours. Among the latter, the K index is the most used, which is a quasi-logarithmic geomagnetic index, which represents the disturbance of the local geomagnetic field, and is based on the diurnal variation curve of the geomagnetic observatory on calm days. This is measured at three hour intervals. At a planetary level, the Kp index is defined, which is obtained by calculating the weighted average of the K indices observed in a global network of geomagnetic observatories.

The US agency NOAA has defined a scale to quantify the intensity and impact of geomagnetic storms. It consists of five possible values ​​(G1 to G5) related to the Kp index value reached and represents the average frequency with which they occur in each solar cycle.

Space Weather involves the study of environmental conditions between the Sun and Earth caused by solar activity and the risks associated with it.

Currently, there are many organizations around the world that specialize in space weather, working to monitor the sun and its impact on Earth, aggregating data from satellites, geomagnetic observatories, and other sensors. In Spain, the National Space Meteorology Service (SEMNES) is carrying out these monitoring and dissemination missions, with the participation of the National Geographic Institute providing data from its geomagnetic observatory.

Effects of geomagnetic storms

solar storm

The Auroras

Geomagnetic storms are usually small in scale and do not cause any damage. Northern lights in the northern hemisphere and southern lights in the southern hemisphere are the most pleasant manifestations of geomagnetic storms, created by charged solar particles interacting with Earth's atmosphere. When a large amount of material arrives due to the influence of a coronal mass ejection, Earth's magnetic field tries to deflect these particles, but eventually they end up penetrating the area near the magnetic poles and making contact with the upper layers of the atmosphere. these layers, the particles interact with the atmosphere in the Gases (oxygen, nitrogen) interact with each other, which will adjust the color you see.

Although auroras are common at high latitudes, when associated with extreme geomagnetic storms, they can be seen at much lower latitudes. So, for example, the great storm "Carrington Event" on September 1, 1859 produced auroras in Europe, Central America, and Hawaii. In Spain, this phenomenon was very notorious and was reported by the local media at the time.

Geomagnetic storm damage

In less common cases where geomagnetic storms are more intense, they can cause damage to infrastructure and people.

On the one hand, satellites run the risk of being affected by the action of energetic charged particles, which can damage its structure or affect its functioning. This could affect positioning systems, navigation systems, or communications satellites, causing significant damage and financial loss to all infrastructure that relies on these systems to operate.

On the other hand, power distribution networks and underground metallic pipes that can induce geomagnetically induced currents (GICs) are very sensitive. This type of current can be extremely damaging to electrical networks, causing high-voltage transformers to overheat or even burn out, as happened during the geomagnetic storm of March 13, 1989, that caused a famous blackout in Quebec (Canada). Oil and gas pipelines are susceptible to corrosion due to GIC, while signaling systems for rail traffic can be damaged, posing a risk.

People are also affected by strong geomagnetic storms when traveling by plane. For this reason, aircraft on polar routes are often diverted during intense geomagnetic storms, and astronauts must remain on board until the effects of the storm subside.

I hope that with this information you can learn more about geomagnetic storms and their characteristics.


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