HR: 0800h
AN: SM41A-0326    [Abstracts]
TI: Probability Distributions of Electron Precipitation at High Magnetic Latitudes
AU: Gentile, L C
EM: louise.gentile.ctr@hanscom.af.mil
AF: Boston College, 402 St. Clement's Hall, 140 Commonwealth Ave, Chestnut Hill, MA 02467,
AU: * Ober, D M
EM: daniel.ober@hanscom.af.mil
AF: Air Force Research Laboratory, VSBXP, 29 Randolph Road, Hanscom AFB, MA 01731,
AU: Holeman, E G
EM: ernest.holeman.ctr@hanscom.af.mil
AF: Boston College, 402 St. Clement's Hall, 140 Commonwealth Ave, Chestnut Hill, MA 02467,
AU: Hardy, D A
EM: david.hardy@kirtland.af.mil
AF: Air Force Research Laboratory, VS, 3550 Aberdeen Ave SE, Kirtland AFB, NM 87117,
AU: Burke, W J
EM: william.burke2@hanscom.af.mil
AF: Boston College, 402 St. Clement's Hall, 140 Commonwealth Ave, Chestnut Hill, MA 02467,
AU: Burke, W J
EM: william.burke2@hanscom.af.mil
AF: Air Force Research Laboratory, VSBXP, 29 Randolph Road, Hanscom AFB, MA 01731,
AU: Bounar, K H
EM: khaled_h_bounar@raytheon.com
AF: Raytheon IDS, 350 Lowell Street, M/S AME970D, Andover, MA 01810,
AB: Starting in the early 1980s investigators at the Air Force Research Laboratory have sought to exploit information contained in the massive database accumulated by the electron and ion spectrometers on spacecraft of the Defense Meteorological Satellite Program (DMSP). One objective has been to characterize particle precipitation at high latitudes by determining the average properties of precipitating electrons as functions of magnetic latitude (MLat), magnetic local time (MLT) and the level of geomagnetic activity specified by the Kp index. Parameters used in the present analysis, integral number flux, integral energy flux, and average energy of precipitating electrons are widely used in the space weather community to estimate auroral ionospheric conductance. In the original Hardy-85 model data from the SSJ3 sensor on DMSP F2 and F4 were used to calculate "average" quantities for given MLat-MLT-Kp bins, assuming that sampled populations were reasonably singular and normally distributed. The current investigation tests these assumptions using the much larger SSJ4 data set from DMSP F7 though F15. We find that at all local times and latitudes probability distributions for detecting any of the three parameters is always lognormal and often nonsingular. Lognormal distributions have inherent positive skews with the average value larger than the most probable value. Consequently, ionospheric conductance maps based on average values provide conductance values that are too high. Using the most probable value of each distribution would provide a better estimate of the conductivities but given the lognormal and nonsingular character of the distributions even the most probable value is an unlikely predictor of actual conditions.
DE: 2704 Auroral phenomena (2407)
DE: 2716 Energetic particles: precipitating
DE: 2722 Forecasting (7924, 7964)
DE: 7959 Models
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting