POES Space Environment Monitor, Energetic Particles
The TIROS/NOAA satellite series, also known as POES, is designed to meet the National Oceanic and Atmospheric Administration's need for operational, remote sensing products for numerical weather and space environment forecasts. The TIROS designation represents the experimental classification of a new instrument configuration while NOAA represents the operational classification. For January 1979 through present, the National Geophysical Data Center archives data from the POES Space Environment Monitor instrument. Subcomponents of the SEM include: HEPAD (High Energy Proton and Alpha Detector), MEPAD (Medium Energy) and TED (Total Energy) data from TIROS and NOAA satellites. The satellites are in sun-synchronous orbits at 850 kilometers altitude, an orbital period of 102 minutes and an inclination of 99 degrees. The orbital plane is tilted toward the sun in the Northern Hemisphere. Usually, two satellites are operational at all times.NOAA's Polar Orbiting Environmental Satellites (POES) (formerly known as TIROS for Television and InfraRed Observation Satellite) carry a suite of instruments that detect and monitor the influx of energetic ions and electrons into the atmosphere and the particle radiation environment at the altitude of the satellite. Both phenomena vary as a result of solar and geomagnetic activity. Beginning with the NOAA-15 satellite, an upgraded version of the Space Environment Monitor (SEM-2) is being flown. A number of SEM-2 instruments have been procured and it is anticipated that the SEM-2 instruments will be included on the NOAA/POES satellites until superceded by the NPOESS satellite program sometime after 2010.Because the SEM-2 instruments differ significantly from the earlier SEM-1, there has been a complete revision to the data processing and archiving process. A number of improvements have also been included. Among these are incorporating up-to-date satellite orbit information and magnetic field models in the calculation of various magnetic coordinates, and improved data quality control.The Total Energy Detector (TED) is designed to measure the energy flux carried by auroral particles, both positively charged ions (assumed here to be protons) and electrons, into the polar atmosphere. The magnitude and spatial extent of this energy flux are good measures of both the level of auroral activity and the atmospheric response to that energy input.The Medium Energy Proton and Electron Detector (MEPED) includes a set of solid-state energetic particle detectors that monitor the intensities of protons and electrons over a range extending from 30 keV to more than 200 MeV. Particles having those energies include the radiation belt (Van Allen belt) populations, the particles in energetic solar particle events (solar proton events), and the low energy portion of the galactic cosmic ray population. Enhanced fluxes of these particles entering the atmosphere can produce significant and widespread degradation in short-wave radio propagation; in extreme cases even radio blackouts. The energetic particles also contribute to astronaut radiation exposure, especially on high inclination orbit missions during energetic solar particle events.
Metadata Last Modified: 2011-08-19
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