Auroral oval representation (1975)

Auroral oval representation (1975)

552 l) Ihl rli,x Rich, 1' J. and Maynard. N. ('. 1198cJ) ('onscqucilccs tfl using simple anals, lica] I'tlllclii)llS for the high-latitude con',ecl...

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552

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Ihl rli,x

Rich, 1' J. and Maynard. N. ('. 1198cJ) ('onscqucilccs tfl using simple anals, lica] I'tlllclii)llS for the high-latitude con',eclion eIeclric field. ,/. ,/e,/~/#l'x. [¢cx 94, 3(,S7

Department of Space Physics and Astrononly, Box I,'492. Rice University. Houston, TX 77251. U.S.A.

the high lalilude region ',,.as separated into .',~; /otw.~ H~ corrected geomagnetic latitude (from 50 Io 90 ) and 4,": half-hour zones in nmgnclic local Ihnc. Epstein lranshiol: functions :.ne used to represent the spatial '~arialion. and a~ Eouricr series of order 6 i> used to reprcsen! the tcnlporal variation resulting in a Iota] of 364 model coelficienls. ('oefl]cicnl sets ~ere delcrlnincd for the elcclron energy flux, Ihc lltllllber l]ux. and the Pedcrsen and Hall conduclivilies l'hc laltcr is found with the help of cinpirical rcktiicmships between the conductiviiies al/d the cicclron ellCl'g} I'ltlx alld average energy.

P(iraltl¢'l¢'r Precipitating electron energy flux, characteristic eleclrc, n energy. Pederseri and tlall conductance ill anroral zonc.

. It'a tied i/iLl F O R T R A N code may bc available from the authors (scc "'lleppncr Maynard Rich Electric Field Model", p. 551).

B,,'i~!/ ~hv,~vqplion Data fi'om the low energy electron experiment ( L E E ) on lhc AE-(" and -D satellites have been used to determine tile distribution of the energy flux oF precipitating auroral electrons and their average energy for different levels of geomagnetic activity. Thc slndy is based on 30,407 individual measurements I'rom January 1974 to April 1976. Tables of energy flux and characteristic energy were produced Ibr Ibm" ranges of auroral electrojet indices (AE). Each table shows the variation with invariant latitude (30 bins between 50 and 88 ) and magnetic local time (24 bins between 0 and 24). En-ipirical relationships arc used to produce similar tables Ibr the Pederscn and Hail condnctances. Robinson ct a/. (1987) lmve pointed out errors in the calculation of conductances in the Rice model, lnlprovemenls wcre suggested by Kamide el a/. (1989).

R41brem.~,~ l lardy, I). A., Gussenhoven, M. S. and t toleman, IL (19<'45) A statistical model of the aroral electron precipitalion..I. .qCOlUOV,. Res. 90, 4229. tlardy. D. A., Gusscnhovcn, M. S. and Raistrick, R. (I':J87) Statistical and functional representations of the pattern of aLli-c,ra] energy flnx, iiunlber flnx, and conductivilv..1. geop/U'v. Re.';. 92, [2275. Robinson, R. M., Vondrack, R. R.. Miller, K., Dabbs. T. and t lardy, D. A. (1987) On calculating ionospheric conductivities from tile flux and energy of precipitating oleoIrons..I. ,teop/U'.';. Rr.>',. 92, 2565.

Rice Electron Precipitation Model (1982) R. W. Spire. P. tt. Reiff. k. J. Mahcr

,4 vailahilily F O R T R A N code nlay be available from the authors. Rcl~'re#zce.v Kamidc, Y., lshihara, Y., Killccn. '1". L.. Carven, .1. D., Frank, L. A. and Heelis, R. A. (1989)Combining electric field and aurora observations from DE1 and 2 with ground inagnetometer records 1o cstimale ionospheric electromagnetic quantities. J. geoph.rs. Re:,. 94, 6723. Robinson, R. M., Vondrak, R. R., Miller. K., Dabbs, T. and ttardy, D. (1987) On calculating ionospheric rend uctances fl'om the flux and energy of precipitating electrons..I. geOldO's. Res. 92, 2566. Spire. R. W., Reifl', P. H. and Maher, L. J. (1982) Precipitating electron energy flux arid auroral zone conductances An empirical model. ,I..qeo/;'lo'.<.. Re.,,'. 87, 8215.

AFGL Electron Precipitation Model (1987) D. A. Hardy, M. S. Gussenhoven Air Force Geophysics Laboratory. I | a n s c o m AEB. MA 01731. U.S.A. NSI-DECnel : A F G L : : H A R D Y P~IIXIIHCIcI" Integral energy flux and number flux ,;fl" precipitating auroral electrons, Pcdersen and I kill conductivity.

Briei de.scrip'lio#l This model provides the integral energy and number flux of precipitating auroral electrons t\w seven levels of magnetic activity (Kp - 0, 1, 2, 3, 4. 5. and 6 and greater). It is based on about 14.1 million spectra (50 20 keV) from the SS.I'3 detectors on the D M S P F2 and F4 satellites and tile CRI,251 detector on the P78-1 satellite. At each level of aclivit)

AFGL Ion Precipitation Model (1989) D. A. I lardy, M. S. Gusscnhoven, D. Brautigam (for address sce "'AFGL Electron Precipitation Model" above) PLII'¢IIII('IuI" Inlegral energy lltlX, number Ill.ix, and average energy of precipitating auroral ions (0.03 30 keV),

Briqf de.vcriptio. This model provides the integral energy and number flux and the average energy of precipitating auroral ions as a function of corrected geomagnetic latitude (CGL). magnetic local time (M.L.T). and nlagnctic activity (Kp). About 26.5 million individual l-,~ spcctr:.i l'rOlll tile NSd/4 detectors on thc I)M£'P 1:6 and t:7 satellites were sampled into 30 C(}I. bins (50 to 90 ) and into aS half-hour bins for sevcn levels of magnetic activity (K F, :: (I to 6). The paper presents (I) plots of average speclra, (2i histograms of average integral encrgy number flux and a,,cragc ellcrgy as a function ol'('G[, a l o n g t h c n o o r t midnight andda:~.n dusk meridians, arid(3) color-coded polar spcctr(~grams of tile same quantities m a M.I,.T ( ' G L c o o r d i n a l c s y s l c m . &jercm'<><, Hard S, l). A.. Gussenho,.cn. M. S. and Brautigam. D. (1989) A shitistical model of auroral ion precipitation..I. geophv.<,. Re,v. 94., 370.

Auroral Oval Representation (1975) R, H. Holzworth, ('.-1. Mcng Space Science Laboratory. Berkcley, ('A 94720. U.S.A.

I_!niversity

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Mathematical represenlalion of the auroral oval.

Solar-terrestrial models and application software Brief description This model provides a mathematical representation of the aui-oral oval by a simple seven parameter Fourier series. Holzworth and Meng (1975) list coefficients for the seven Feldstein (1963) ovals which correspond to different levels of geomagnetic activity. References Feldstein, Y. I. (1963) On morphology and auroral and magnetic disturbances at high latitudes. Geomagn. Aeron. 3, 138. Holzworth, R. H. and Meng, C.-I. (1975) Mathematical representation of the auroral oval. Geophys Res. Lett. 2, 377.

Auroral Absorption Model (1983) A. J. Foppiano, P. A. Bradley Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OXll OQX, U.K. Parameter Probability that absorption at 30 MHz exceeds I dB; median absorption. Brief description This model provides information for HF propagation calculations at high latitudes. It is based on the long record of worldwide riometer measurements. The model describes the probability Q~ that the HF absorption exceeds 1 dB. Q, is a parameter important for long-term predictions. Simple empirical expressions are given for the dependence on corrected geomagnetic latitude, longitude, and local time, solar activity (12 months smoothed sunspot number), and season. Assuming a loDnormal distribution for the cumulative absorption probability, the authors deduce a simple linear relationship between Q ~and the median absorption. Availability PC software may be available from the authors. References Foppiano, A. J. and Bradley, P. A. (1983) Prediction of auroral absorption of high-frequency waves at oblique incidence. Telecomm. J. 50, 547. Foppiano, A. J. and Bradley, P. A. (1984) Day-to-day variability of riometer absorption. J. atmos, terr. Phys. 46, 689.

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the stratosphere, from 10 km up to about 45 km, where the temperature increases; the mesosphere, from 45 km up to about 95 km, where the temperature decreases again; the thermosphere, from 95 km to about 400 km, where the temperature increases again ; and the exosphere, above about 400 km, where the temperature is constant. The first global models of the upper atmosphere were developed by L. G. Jacchia in the early sixties based on theoretical considerations and satellite drag data. Since the launch of Sputnik 1 in 1957, orbit decay of artificial satellites has been used to derive atmospheric data. Several national and international organizations have established committees for the development of atmospheric reference models, e.g. the International Civil Aviation Organization (ICAO), the Committee on Space Research (COSPAR), and the Committee on Extension to the Standard Atmosphere (COESA). Probably the most widely used and well established model is the COSPAR International Reference Atmosphere (CIRA), an effort that started in 1961 with the publication of CIRA-61. CIRA-72, the third generation of this model, includes Jacchia's 1971 model. With the launch of the OGO 6 satellite in 1969, in situ measurements of atmospheric parameters by mass spectrometer became available. At about the same time, ground-based incoherent scatter radars started to monitor the thermospheric temperature. A. E. Hedin and his co-workers combined data from these two data sources to establish the Mass Spectrometer Incoherent Scatter (MSIS) models: MSIS-77, -83, -86. The CIRA and MSIS groups joined forces in 1986; MSIS-86 constitutes the upper part of CIRA86. Description of storm effects remains one of the most challenging topics in thermospheric modeling. DE-2 wind measurements have shown characteristic highlatitude wind signatures caused by similar IM F (interplanetary magnetic field)-dependent signatures in ionospheric convection.

ATMOSPHERE

The atmosphere can roughly be characterized as the region from sea level to about 1000 km altitude around the globe, where neutral gases can be detected. Below 50 km the atmosphere can be assumed to be homogeneously mixed and can be treated as a perfect gas. Above 80 km the hydrostatic equilibrium gradually breaks down as diffusion and vertical transport become important. The major species in the upper atmosphere are N2, O, 02, H, He. Temperature-oriented nomenclature differentiates the strata of the atmosphere as follows : the troposphere, from sea level up to about 10 km, where the temperature decreases ;

U.S. Standard Atmosphere (1976) National Geophysical Data Center National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO 80303, U.S.A. (303) 497-6136 Parameter Atmospheric density, temperature, and pressure. Brief description The work of the U.S. Committee on Extension to the Standard Atmosphere (COESA), established in 1953, led to the 1958, 1962, 1966, and 1976 versions of the U.S. Standard Atmosphere. These models were published in book form