NOAA POES Hemispheric Power

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NOAA POESPolar Orbiting Environmental Satellites (POES) are a constellation of spacecraft that provide near continuous monitoring of the terrestrial and space environment over the polar regions. [[Glossary/POES]]- Hemispheric Power

Hemispheric Power is a measure of auroral activityusually refers to visible aurora and the particles that create them, but may also refer to electrical currents that flow in the auroral region. One measure of auroral activity is hemispheric power. Charged particles (mainly protons and electrons) that fall, or precipitate, into the auroral zones collide with the upper atmosphere particles. As a result, the charged particles slow and eventually stop. In so doing they transfer their kinetic energy to the upper atmosphere. The rate of particle energy deposition integrated over the northern or southern auroral zone is called hemispheric powerA measure of auroral activity. Charged particles from the magnetosphere or solar wind can drive into the auroral zones and collide with the upper atmosphere particles. The collisions slow the charged particles, causing them transfer their kinetic energy to the upper atmosphere. The rate of particle energy deposition summed over the auroral zones is called hemispheric power.. The basic unit of power is a Watt. Because the auroral zones cover large areas, a vast amount of power is deposited and a more useful unit for describing the power input is GigaWatt (GW).

NOAA operates a fleet of satellites called Polar Orbiting Environmental Satellites (POESPolar Orbiting Environmental Satellites (POES) are a constellation of spacecraft that provide near continuous monitoring of the terrestrial and space environment over the polar regions. [[Glossary/POES]], [[1]]). These satellites are equipped with particle detectors to measure the power deposition, however they only measure the power along the orbit track. Particle data are collected over the high-latitude regions from 45 degrees poleward to 45 degrees equatorward. [[2]] A statistical fitting routine was developed by NOAA [Fuller-Rowell and Evans, 1987] to extend the orbit track observations to provide an estimate of hemispheric powerA measure of auroral activity. Charged particles from the magnetosphere or solar wind can drive into the auroral zones and collide with the upper atmosphere particles. The collisions slow the charged particles, causing them transfer their kinetic energy to the upper atmosphere. The rate of particle energy deposition summed over the auroral zones is called hemispheric power.. The power estimate uses a normalization factor to account for how effective each satellite was in sampling the auroratransient displays of light, often displaying as moving curtains and rays, at high latitudes associated with geomagnetic disturbances during its transit over the polar region.

This cygnet shows a three-day history of the estimates of hemispheric powerA measure of auroral activity. Charged particles from the magnetosphere or solar wind can drive into the auroral zones and collide with the upper atmosphere particles. The collisions slow the charged particles, causing them transfer their kinetic energy to the upper atmosphere. The rate of particle energy deposition summed over the auroral zones is called hemispheric power. from all POESPolar Orbiting Environmental Satellites (POES) are a constellation of spacecraft that provide near continuous monitoring of the terrestrial and space environment over the polar regions. [[Glossary/POES]] spacecraft, as well as the European MetOp satellite, which carries sensors similar to those on POESPolar Orbiting Environmental Satellites (POES) are a constellation of spacecraft that provide near continuous monitoring of the terrestrial and space environment over the polar regions. [[Glossary/POES]]. Presently, the NOAA POESPolar Orbiting Environmental Satellites (POES) are a constellation of spacecraft that provide near continuous monitoring of the terrestrial and space environment over the polar regions. [[Glossary/POES]] spacecraft are numbered 15 through 19. Data from each spacecraft are color-coded and then overlaid for comparison. Southern hemisphere data are displayed with a "+" and northern hemisphere data are displayed with a "*". Also plotted with a dashed curve is the estimate of total hemispheric powerA measure of auroral activity. Charged particles from the magnetosphere or solar wind can drive into the auroral zones and collide with the upper atmosphere particles. The collisions slow the charged particles, causing them transfer their kinetic energy to the upper atmosphere. The rate of particle energy deposition summed over the auroral zones is called hemispheric power. from a auroral model called OVATION PRIME. This model can provide a short term forecast of the hemispheric powerA measure of auroral activity. Charged particles from the magnetosphere or solar wind can drive into the auroral zones and collide with the upper atmosphere particles. The collisions slow the charged particles, causing them transfer their kinetic energy to the upper atmosphere. The rate of particle energy deposition summed over the auroral zones is called hemispheric power. based on solar windplasma flowing out from the sun [[Glossary/ solar wind]] speed and the strength and orientation of the interplanetary magnetic field [Newell et al., 2009 and 2010]

Examples

This link shows the POESPolar Orbiting Environmental Satellites (POES) are a constellation of spacecraft that provide near continuous monitoring of the terrestrial and space environment over the polar regions. [[Glossary/POES]] Hemispheric Power compared with the the Kp IndexThe Kp index indicates the magnitude of geomagnetic disturbance on a 0-9 scale, with zero being very quiet and 9 indicating a major geomagnetic storm. This cygnet shows a three-day history of the real-time Kp index in 3 hours periods produced by the NOAA Space Weather Prediction Center. See also the "Kp Indicies" Cygnet wiki page. [http://iswa3.ccmc.gsfc.nasa.gov/wiki/index.php/KP_Indices] from the same date range. Notice that the Hemispheric Power tracks the Kp index pretty well, indicating that geomagnetic activity increases the amount of energy deposited into the upper atmosphere by auroral protons and electrons. This example is a “minor” disturbance. [[3]]

Here is another example of the onset of a “moderate” storm in the middle of July 2012. [[4]]

Reference:

[[5]] Fuller-Rowell, T. and Evans, D.: Height-integrated Pedersen and Hall conductivity patterns inferred from TIROS-NOAA satellite data, J. Geophys. Res., 92, 7606, 1987.

Newell, P.T., T. Sotirelis, and S. Wing (2010), Seasonal variations in diffuse, monoenergetic, and broadband auroratransient displays of light, often displaying as moving curtains and rays, at high latitudes associated with geomagnetic disturbances, J. Geophys. Res., 115, A03216, doi:10.1029/2009JA014805.

Newell, P.T., T. Sotirelis, and S. Wing (2009), Diffuse, monoenergetic, and broadband auroratransient displays of light, often displaying as moving curtains and rays, at high latitudes associated with geomagnetic disturbances: The global precipitation budget, J. Geophys. Res., 114, A09207, 216, doi:10.1029/2009JA014326.

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