Joint radar-satellite determination of the effective recombination coefficient in the auroral<i>E</i>region

Watt, T. M.; Newkirk, L. L.; Shelley, E. G.

doi:10.1029/ja079i031p04725

Cited by 22 publications

(5 citation statements)

References 12 publications

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“…For comparison with the 13tef f values obtained photometrically we have calculated an average value of aef f = 1.8 ___ 0.4 x 10 -7 cm 3 sec -• for Nemax = 8 X 10 5 el cm -3 using Chatanika radar data for heights of h = 109 and 118 km during this experiment. This value is also very close to the Otef f values obtained in this height range by both Baron [1974] and Watt et al [1974]. Direct comparison between an in-situ rocket Ne profile made during this event and that obtained simultaneously from the incoherent scatter radar shows excellent agreement.…”

Section: Introductionsupporting

confidence: 84%

Structure and dynamics of ionization and auroral luminosity during the auroral events of March 16, 1972, near Chatanika, Alaska

Hunsucker¹,

Romick²,

Ecklund³

et al. 1975

Radio Science

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During the period 1000–1030 UT on March 16, 1972, a very dynamic auroral event occurred in the latitudinal region from College to Fort Yukon, Alaska. Simultaneous observations of this auroral event were made with an all‐sky camera, a geomagnetic meridian scanning photometer, an incoherent scatter radar, a three‐component magnetometer, a 30‐MHz riometer, and two VHF/UHF auroral radars. The basic purpose of this report is to illustrate the advantages of such coordinated measurements and the possibilities for future experiments. These preliminary results point out many relationships which, although not hitherto unknown, are important to the understanding of the auroral ionosphere. Paramount among these are (1) intense discrete auroral forms (> 25 kR in 4278 Å) are associated with enhanced E‐layer electron densities near 106 electrons/cm3; (2( the riometer data and the height of maximum Ne from the incoherent scatter radar suggest that few energetic (> 40 kev) particles were precipitating during this event; (3) enhanced regions of VHF backscatter seem to be associated with eastward and westward electrojet current systems but do not spatially correspond to the regions of high Ne or bright auroral forms; and (4) the collective data yield a description which indicates that this period is associated with the Harang discontinuity region of the auroral current systems.

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Section: Introductionsupporting

confidence: 84%

Structure and dynamics of ionization and auroral luminosity during the auroral events of March 16, 1972, near Chatanika, Alaska

Hunsucker¹,

Romick²,

Ecklund³

et al. 1975

Radio Science

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“…electrons was observed over the polar cap for more than 40 hours by the energetic particle detector (EPD) [Venkatarangan et al, 1975] and the soft particle spectrometer (SPS) [Heikkila et al, 1970], instruments on Isis 2, which was in a circular, near-polar, dawn-dusk orbit at • 1400 km. Additional observations were made by electron spectrometers on the polarorbiting satellites Ariel 4 (Iowa) and 1971-089A (Lockheed) [Watt et al, 1974]. These data reveal a central region of generally uniform fluxes, having bordering and embedded features of greater intensity and a harder energy spectrum.…”

Section: Introductionmentioning

confidence: 99%

Electron fluxes over the polar cap, 1. Intense keV fluxes during poststorm quieting

Foster¹,

Burrows²

1976

J. Geophys. Res.

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Intense fluxes of keV electrons were observed over large regions of the north polar cap during two periods of magnetospheric quieting following large storms. These fluxes were distinctly field aligned, had energy spectra peaked at both • 100 eV and •2 keV, and were not observed in the conjugate hemisphere. A search for similar fluxes in the interplanetary medium or the dayside magnetosheath yielded negative results. In one instance the polar cap fluxes were observed for •40 hours during a period of large-scale expansion of the bow shock. The flux intensity and spectrum varied with observed changes in the bow shock configuration. This and other evidence leads us to suggest that these fluxes were accelerated by a potential barrier located either at the downstream bow shock or within the magnetospheric cavity on field lines intersecting the distended bow shock. The flux intensity and energy spectrum above I keV were similar over the polar cap and in the morningside plasma sheet, a finding which suggests that electrons in these regions had a similar source during these events. From the data we infer that the source of the polar cap fluxes was, in general, spatially and temporally uniform and that the structure within the region of their observation was related to processes and field line configurations that are internal to the magnetosphere. Details of the structure of the high-latitude magnetosphere are examined by using the polar cap fluxes as tracer particles. It is found that keV electrons have attenuated access to the postnoon region of closed field lines from high latitudes but are excluded from lower latitudes on the morningside by the prenoon cleft.

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“…Validation of these computations has been sparse. Examples based on auroral particle fluxes include those of Ulwick and Baron [1973], Watt et al [1974], and Vondrak [1981]; other results have been reported based on particle fluxes during PCA events [Reagan and Watt, 1976]. In general, the motivation of those previous studies was to use the simultaneous ionization and particle flux measurements for determination of the altitude profile of the effective recombination coefficient.…”

Section: Introductionmentioning

confidence: 99%

Inference of high‐latitude ionization and conductivity from AE‐C measurements of auroral electron fluxes

Vondrak¹,

Robinson²

1985

J. Geophys. Res.

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Electron fluxes in the kilovolt energy range measured by the AE‐C satellite have been used to infer the latitudinal distribution of ionization at high latitudes in the altitude range 90 to 200 km. These distributions are compared with simultaneous measurements of electron density by the Chatanika incoherent scatter radar. The study was based on more than 120 electron density profiles obtained on three different nights at magnetic local times between 0200 and 0400. The calculated distributions agree very well with the altitude and latitude distributions measured by the radar. The only obvious difference was the presence in the radar data of additional ionization produced by solar illumination. We also compared the height‐integrated electrical conductivities computed from the measured profiles and those inferred from the satellite measurements. For Hall and Pedersen conductances greater than 5 mhos, the agreement is within 25%. The data were also used to deduce the altitude profile of the effective recombination coefficient. This profile agrees well with the results of previous studies.

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Joint radar-satellite determination of the effective recombination coefficient in the auroralEregion

Cited by 22 publications

References 12 publications

Structure and dynamics of ionization and auroral luminosity during the auroral events of March 16, 1972, near Chatanika, Alaska

Structure and dynamics of ionization and auroral luminosity during the auroral events of March 16, 1972, near Chatanika, Alaska

Electron fluxes over the polar cap, 1. Intense keV fluxes during poststorm quieting

Inference of high‐latitude ionization and conductivity from AE‐C measurements of auroral electron fluxes

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