P. Stubbe

Technical University of Denmark

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

H. Kopka

Max Planck Society

M. T. Rietveld

European Incoherent Scatter Scientific Association

R. Graham Barr

Columbia University Irving Medical Center

B. Thidé

Swedish Institute of Space Physics

ÅH

Å. Hedberg

Cornell University

H. Derblom

Swedish Defence Research Agency

E. Nielsen

New Mexico State University

T. B. Jones

Florida State University

R. L. Dowden

Research Institute for Electromagnetic Materials

E. N. Sergeev

N. I. Lobachevsky State University of Nizhny Novgorod

Cooperative Institutions

Max Planck Institute for Astronomy

Max Planck Society

Swedish Institute of Space Physics

Max Planck Institute for Solar System Research

Radiophysical Research Institute

University of Leicester

Technical University of Denmark

Uppsala University

Institute of Terrestrial Magnetism Ionosphere and Radio Wave Propagation

Centre National de la Recherche Scientifique

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

A hysteresis effect in the generation of field‐aligned irregularities by a high‐power radio wave

Radio Science (1983)

T. B. Jones T. R. Robinson P. Stubbe H. Kopka

The anomalous self‐absorption of a high‐power radio wave measured during recent ionospheric modification experiments exhibits a hysteresis effect. These results are consistent with the assumption that the growth of field‐aligned irregularities due to the interaction of a high‐power pump wave and the ionospheric plasma occurs in two stages. During the first stage, striation growth is due to an instability which has a threshold independent of striation amplitude. When the striation level is sufficiently high, the threshold of the second stage is reached. The second‐stage threshold is dependent on the striation amplitude. The state of background ionosphere is also found to be an important factor influencing the observed effects.

Striation

Hysteresis

10.1029/rs018i006p00835

Cite

Citations (29)

Pc1 ionospheric electric field oscillations

Annales Geophysicae (1988)

M. T. Rietveld H. Kopka P. Stubbe

Source

Cite

Citations (7)

Daytime scintillations induced by high‐power HF waves at Tromsø, Norway

Journal of Geophysical Research Atmospheres (1987)

Santimay Basu Sunanda Basu P. Stubbe H. Kopka J. Waaramaa

During March 1984 the high‐power HF heating facility located at Ramfjordmoen (69.6°N, 19.2°E geographic) near Tromsø, Norway, was used to modify the ionospheric F region in the daytime. The intensity and phase scintillations of 250‐MHz transmissions from the quasi‐stationary polar beacon satellite were measured when the ray path from the observing site to the satellite intercepted the modified ionospheric volume. Narrow band spectral enhancements corresponding to an irregularity scale length of 750 m were detected in the intensity spectra when the radiated HF power developed an estimated power density of about 0.3 mW/m² at the height of reflection. Spectral enhancements at larger scales were not detected in the phase spectra. From the growth and decay of the intensity spectral enhancements during the successive 10‐min “on” and 10‐min “off” periods of the heater the e ‐folding growth and decay times of ∼750 m irregularities were estimated to be on the order of 30 s and 2 min, respectively. The threshold power densities required for the generation of the observed irregularity scale sizes were calculated from the self‐focusing instability theory of Cragin et al. (1977) by the use of ionospheric background parameters measured by the EISCAT radar. The theoretical estimates were found to be within a factor of 2 of the HF power densities employed in the experiment. The presence of Fresnel oscillations in the intensity and phase spectra were attributed to a limited irregularity layer thickness less than 50 km. By using the formulations of the thin phase screen theory, it was found that the observed intensity scintillations at 250 MHz correspond to irregularity amplitudes (Δ N/N ) of 3% with an outer scale of 1 km.

Intensity

10.1029/ja092ia10p11149

Cite

Citations (24)

Excitation of longitudinal (field-aligned) currents by modulated HF heating of the ionosphere

Journal of Atmospheric and Solar-Terrestrial Physics (1997)

N. D. Borisov P. Stubbe

Longitudinal field

High frequency

10.1016/s1364-6826(97)00019-9

Cite

Citations (9)

On the frequency dependence of ELF/VLF waves produced by modulated ionospheric heating

Radio Science (1989)

M. T. Rietveld P. Stubbe H. Kopka

We present results of the local field strength and, for the first time, apparent source height as a function of frequency from 200 to 6600 Hz of ELF/VLF waves produced in the auroral D region through modulated RF heating using the ionospheric heating facility near Tromsø, Norway. These data show, besides the normal amplitude peaks near 2, 4, and 6 kHz, the occasional presence of peaks at intermediate frequencies, especially in the right‐hand circularly polarized mode. A comprehensive model has been developed to explain the data, using a full wave solution of the ELF/VLF waves produced by the self‐consistently calculated source currents, and correcting for the effects of finite source current extent and multiple Earth‐ionosphere reflections. The model can reproduce the amplitudes and source heights for typical sweeps. The irregular peaks occasionally seen can also be reproduced by invoking interference between the downcoming wave and a partially reflected whistler mode wave from sharp electron density gradients in the ionosphere such as sporadic E layers. The model seems to work well above about 600 Hz, but below that it increasingly underestimates the measured amplitudes.

Whistler

Extremely low frequency

10.1029/rs024i003p00270

Cite

Citations (70)

On the penetration of upper hybrid waves into a plasma depletion

Advances in Space Research (2004)

С. М. Грач Yu.E. Men’kova P. Stubbe

Penetration (warfare)

10.1016/j.asr.2004.03.014

Cite

Citations (6)

Evolution of subkilometer scale ionospheric irregularities generated by high‐power HF waves

Journal of Geophysical Research Atmospheres (1997)

Sarbani Basu Emanoel Costa R. C. Livingston K. M. Groves H. C. Carlson

Electron density irregularities in the F region excited by the European incoherent scatter (EISCAT) high‐power high‐frequency (HF) facility in Ramfjordmoen, Norway, have been studied in detail by observing scintillations of 250‐MHz satellite signals traversing the HF beam. Spaced antenna measurements were performed to determine the temporal structure of scintillation and the drift of the irregularities. Studies of scintillation spectra indicate that even though the onset occurs nearly simultaneously for all irregularity scale sizes, the electron density irregularities with wavelengths in the range of 50–15 m attain their saturation amplitudes within tens of seconds, whereas longer scale‐size irregularities with wavelengths exceeding 100 m saturate in the timescale of minutes. The threshold power density requirement for the generation of irregularities of different scales has also been studied by the variation of the heater power. It is found that for large‐scale (>100 m) irregularities the threshold power density varies inversely as the irregularity wavelength with a power law index of 4 as predicted by the theories of self‐focusing instability.

10.1029/96ja03340

Cite

Citations (26)

ELF wave generation in the ionosphere using pulse modulated HF heating: initial tests of a technique for increasing ELF wave generation efficiency

Annales Geophysicae (1999)

R. Barr P. Stubbe M. T. Rietveld

This paper describes the results of a preliminary study to determine the effective heating and cooling time constants of ionospheric currents in a simulated modulated HF heating, `beam painting' configuration. It has been found that even and odd harmonics of the fundamental ELF wave used to amplitude modulate the HF heater are sourced from different regions of the ionosphere which support significantly different heating and cooling time constants. The fundamental frequency and its odd harmonics are sourced in a region of the ionosphere where the heating and cooling time constants are about equal. The even harmonics on the other hand are sourced from regions of the ionosphere characterised by ratios of cooling to heating time constant greater than ten. It is thought that the even harmonics are sourced in the lower ionosphere (around 65 km) where the currents are much smaller than at the higher altitudes around 78 km where the currents at the fundamental frequency and odd harmonics maximise.Key words. Electromagnetics (antennae) · Ionosphere (active experiments) · Radio science (non linear phenomena)

10.1007/s005850050805

Cite

Citations (0)

Surveys in Geophysics (1997)

P. Stubbe T. Hagfors

Ponderomotive force

10.1023/a:1006583101811

Cite

Citations (46)

Generation of ELF and VLF waves by polar electrojet modulation: Experimental results

Journal of Geophysical Research Atmospheres (1981)

P. Stubbe H. Kopka R. L. Dowden

The heating facility at Ramfjordmoen near Tromsø, Norway, has been used to modulate the polar electrojet at frequencies in the range 200–5500 Hz. ELF‐VLF signals were received on the ground in the full frequency range, with amplitudes of the order 10 to 100 fT for an effective radiated HF power of 32 MW at 4.04 MHz. A variety of experimental results is presented in this paper.

Electrojet

Modulation (music)

Polar cap

Extremely low frequency

10.1029/ja086ia11p09073

Cite

Citations (135)