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175 - EHP - Estimated Hemispheric Power
Instrument Type: Instrument
Observatory: None
Observation Site: None
Operating Mode:

Instrument Page: EHP

The total hemispheric power input is computed from NOAA/TIROS and DMSP satellite measurements of high latitude precipitating energy flux carried by ions and electons with energies between 300 eV and 20 keV (NOAA/TIROS), or carried by electrons with energies between 460 eV and 30 keV (DMSP). The satellite orbits are sun synchronous around 850 km altitude. Times given are the center of the polar pass used to make the estimate where a typical polar pass takes about 25 minutes. Often there are two satellites operating simultaneously providing coverage at 30 to 60 minute intervals between auroral latitude crossings. The energy flux observations made during a single pass over the polar regions (above about 45 degrees of magnetic latitude) are used to estimate the total precipitating power input to a single hemisphere at that time. This power index was devised by David Evans for the NOAA/TIROS satellites, and adapted for the DMSP satellites by Frederick Rich and William Denig.