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Carpenter, D. L.

Publications and source records attributed to Carpenter, D. L..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Explorer 45 and Imp 6 observations in the magnetosphere of injected waves from the Siple Station VLF transmitter

Results are reported for an experiment in which VLF waves from a transmitter in Antarctica were injected into the magnetosphere along geomagnetic field lines and detected near the magnetic equatorial plane by high-altitude spacecraft. The purpose of this experiment was to conduct a controlled in situ study of VLF wave-particle interactions and to determine the propagation characteristics of the injected waves in the magnetosphere, the regions where VLF emissions are produced, and the effective volume of the magnetosphere illuminated by the transmitter. The results indicate that: (1) the bulk of the satellite receptions occurred during periods of quieting following magnetic disturbances, (2) receptions generally occurred inside the plasmapause, (3) the spacecraft detected predominantly unducted waves, (4) the injected signals could illuminate a large volume of the magnetosphere, and (5) VLF emissions were triggered by nonducted transmitter pulses.

Inan, U. S.↗
NASA NTRS1975

A subauroral and mid-latitude view of substorm activity

Experimental observations from a variety of sources made during a substorm period near 0900 UT on January 2, 1971 have provided evidence confirming mid-latitude and subauroral phenomena associated with magnetic substorm activity. A review of these observations, including ground and balloon observations made near L=4 at the conjugate stations Siple, Antarctica and Roberval, Canada and data obtained from the synchronous-orbit satellite ATS 5 positioned about 2 hours west of the Siple, Roberval meridian, is presented. During the hour before the reported correlated bursts of X rays and VLF noise (Rosenberg et al., 1971), the plasmapause appears to be displaced towards the equator from Siple; resonance conditions along the field lines at Siple were favorable for the observation of results of magnetospheric wave-particle interactions involving electrons with energies exceeding 30 keV. The correlated observations are a potential source of information concerning the relationship of ULF and VHF noise activity to the magnetospheric particle population at middle latitudes; the injection and subsequent drift of low and medium energy electrons during substorms; and enhanced particle precipitation deep within the plasmasphere during substorms.

Carpenter, D. L.↗
NASA NTRS1973

Satellite studies of magnetospheric substorms on August 15, 1968. III - Some features of magnetospheric convection.

New details of unsteady magnetospheric convection and gradual erosion of the plasmasphere during a weak magnetic storm are revealed in the light of presented ground data and OGO-4 and OGO-5 data for August 13-15, 1968. These new findings suggest that westward electric fields of the order of 0.5 mv/m were present in the midnight sector during the substorms studied.

Carpenter, D. L.↗
NASA NTRS1972

Magnetospheric electric fields deduced from drifting whistler paths.

Results of a study in which the amplitude of the E-W component E sub w of the convection electric field in the nightside magnetosphere has been inferred from the observed cross-L motions of whistler ducts within the plasmasphere, and several ducts distributed over 1 to 2 earth radii in L space and over plus or minus deg 15 around the longitude of the Eights, Antarctica, whistler station have been tracked simultaneously. The method appears capable of resolving fluctuations in E sub w with period T equal to approximately 15 min and rms amplitude as low as 0.05 mV/m. For variations with T greater than 1 hour the method has a sensitivity of the order of 0.01 mV/m. Three case studies are presented, two of which illustrate convection activity associated with relatively isolated substorms. In these two cases E sub w reversed from westward to eastward for a period following the decay of substorm bay activity. In the third case the substorm bay activity was prolonged, and E sub w remained westward and at enhanced levels until local dawn. Evidence was found that, at least in a limited longitudinal sector, perturbing substorm E sub w fields can penetrate deep within the plasmasphere. In two of the case studies comparisons of E sub w and the interplanetary magnetic-field theta component show evidence of a possible relation based on brief (less than or equal to 1 hour) southward excursions but not on long preceding southward events.

Carpenter, D. L.↗
NASA NTRS1972

The plasmapause period of magnetic recovery. Combined study of OGO 4, OGO 5 data and of grounded whistler reception

The equatorial structure and dynamics of the plasmasphere during the period of magnetic recovery, lasting from the 13 to 23 of September 1968, are studied. The H(+) ions density profiles measured in the night and afternoon sectors by the excentered orbital satellite OGO 5 and L sub p positions of the plasmapause deduced from the VLF records of the polar orbital satellite OGO 4, are included. Electron densities are calculated from the whistlers received at Kerguelen (L approximately 3, 7) and Byrd (L approximately 7), ground stations 150 degrees of longitude apart.

Corcuff, P.↗
NASA NTRS1972

Two substorm studies of relations between westward electric fields in the outer plasmasphere, auroral activity, and geomagnetic perturbations

Temporal variations of the westward component of the magnetospheric convection electric field in the outer plasmasphere were compared to auroral activity near L = 7, and to variations in the geomagnetic field at middle and high latitudes. The substorms occurred on July 29, 1965 near 0530 UT and on August 20, 1965 near 0730 UT. The results on westward electric field E(w) were obtained by the whistler method using data from Eights, Antarctica (L is approximately 4). All sky camera records were obtained from Byrd, Antarctica, (L is approximately 7), located within about 1 hour of Eights in magnetic local time. It was found that E(w) within the outer plasmasphere increased rapidly to substorm levels about the time of auroral expansion at nearby longitudes. This behavior is shown to differ from results on E(w) from balloons, which show E(w) reaching enhanced levels prior to the expansion. A close temporal relation was found between the rapid, substorm associated increases in E(w) and a well known type of nightside geomagnetic perturbation. Particularly well defined was the correlation of E(w) rise and a large deviation of the D component at middle latitudes.

Carpenter, D. L.↗
NASA NTRS1971

Correlation between convection electric fields in the nightside magnetosphere and several wave and particle phenomena during two isolated substorms.

Correlation of several magnetoionospheric wave and particle phenomena previously linked observationally to magnetospheric substorms and inferred to involve convection electric fields with whistler measurements of convection activity during two relatively isolated substorms. The events occurred at about 0600 UT on July 15, 1965, and about 0500 UT on Oct. 13, 1965. The correlated phenomena include cross-L inward plasma drifts near midnight within the plasmaphere, diffuse auroral radar echoes observed near the dusk meridian, IPDP micropulsations (intervals of pulsations of diminishing period) in the premidnight sector, apparent contractions and expansions of the plasma sheet at about 20 earth radii in the magnetotail, and Pc 1/Pi 1 micropulsation events near or before midnight. Two new vlf phenomena occurred during the October 13 event - a noise band within the plasmasphere associated with a convecting whistler path, and ?hisslers,' falling-tone auroral-hiss forms repeated at intervals of about 2 sec.

Carpenter, D. L.↗