Space Weather

The term "Space Weather" refers to the study of how the conditions in the space affect the earth and its technologic systems. Or, more precisely, it refers to the study of the variations caused in the ionospheric and geomagnetic ways due to the solar activity and the cosmic radiation. The solar-terrestria effects are of great interest; for example, disturbances of the geomagnetic field can damage the energy transmission systems, degrade high-technology shipping systems, besides the rising of auroras. The possibility of prevision of events and its consequences can be converted in improvements of the conditions of transmission of information around the world.

Space Weather study the influence that the sun causes in the earth, due the energy that the sun launches in the space. This energy consists of both charged particles and electromagnetic radiation. As occurs with every active star, the solar energy is originated from fusions that occur in its kernel: the process of nuclear fusion. The variation in the levels of this energy, associated with the way that this energy arrives in the earth, lead to modifications in the terrestrial radiofrequency transmissions. The sun-earth interation can be observed by the levels of solar electromagnetic radiation and the terrestrial geomagnetic activity.

Electromagnetic Radiation

The sun's electromagnetic spectrum is composed by a wide range of radiation including, besides visible, infrared and ultraviolet wavelenghts, X-rays and radio emissions. Sensors in the terrestrial surface and in satellites in space observe certain portions of the sun's spectrum, monitoring their levels and giving indication of how many significative events occur.

Geomagnetic Activity

The sun ejects constantly matter in the form of atomic and sub-atomic particles. This mass of particles is accelerated to velocities in excess of the sun's gravitational field, thus moving to other regions in the solar system. This mass of particles is named solar wind.

Due to the sun's rotation period of 27 days, clouds are liberated in a spiral pattern, and overtakes the earth. As these gaseous clouds arrive in the earth, the geomagnetic field prevents that the particles of the solar wind achieve the earth's surface directly. Magnetic interations between the clouds flows around the field, forming a shell-like holloe with the earth in the center. This hollow, known as the terrestrial magnetosphere, is generally distorted, presenting a form similar to a comet, with its head always pointing directly in the solar wind and the rail in the reverse direction. In the absence of solar activity, the solar wind is uniform, with a velocity of around 400 km/s. Under these conditions, the terrestrial magnetosphere maintains a form an orientation practically stable in the space.

When disturbances in the sun occur, some clouds can be launched at tremendous velocities, As these clouds encounter the terrestrial magnetosphere, this is perturbated, varying the intensity and direction of the geomagnetic field.

The geomagnetic activity, including variations caused in the geomagnetic field by the sun's particles, are monitored by instruments in both the terrestrial surface and the space. High levels of geomagnetic activity act indirectly, degrading the ability of the ionosphere to propagate high-frequency radio signals Thus, are from special interest for those that use this part of the spectrum.

Analyzing and Interpreting the Data

Space Weather uses data obtained from observation stations situated in various parts of the terrestrial surface and from satellites in the space, that collect information with respect to the sun's radiation; the data utilized can be represented by parameters, and from these parameters can be realized analysis of how the terrestrial communications can be affected. Information regarding to Space Weather can be obtained from various sources in Internet, especially specialized research institutes.

See also the following pages, that present detailed information about Space Weather:

Geophysical Alerts: how obtain information about the parameters referring to variations of the solar activity and the geomagnetic activity.
Solar Activity Monitor: a basic monitor of the status of the solar X-rays and the geomagnetic field, updated directly from Internet.
Ciclo Solar: information about the actual status of thr solar cycle with graphics and data for further analysis.
The Sun: description of the most relevant characteristics of this star, and the composition of its atmosphere.
Updated Data: a review of various graphic indicators regarging the actual space weather conditions (solar activity, geomagnetic activity, etc).

References:

The Solar Guide: How to Use Geophysical Alert Broadcasts: on-line guide from the web site of Radio Nederland, with information about how to interpret and to utilize the data given in the geophysical alerts transmissions.