scholarly journals Spatial observations by the CUTLASS coherent scatter radar of ionospheric modification by high power radio waves

1997 ◽  
Vol 15 (11) ◽  
pp. 1412-1421 ◽  
Author(s):  
G. E. Bond ◽  
T. R. Robinson ◽  
P. Eglitis ◽  
D. M. Wright ◽  
A. J. Stocker ◽  
...  
Keyword(s):  
Horizontal Distance ◽  
Radio Waves ◽  
Heated Region ◽  
Coherent Scatter ◽  
Heating Facility ◽  
Incoherent Scatter ◽  
Ionospheric Modification ◽  
Experimental Campaign ◽  
Scatter Radar ◽  
Field Aligned Irregularities

Abstract. Results are presented from an experimental campaign in April 1996, in which the new CUTLASS (Co-operative UK twin-located Auroral Sounding System) coherent scatter radar was employed to observe artificial field aligned irregularities (FAI) generated by the EISCAT (European Incoherent SCATter) heating facility at Tromsø, Norway. The distribution of backscatter intensity from within the heated region has been investigated both in azimuth and range with the Finland component of CUTLASS, and the first observations of artificial irregularities by the Iceland radar are also presented. The heated region has been measured to extend over a horizontal distance of 170±50km, which by comparison with a model of the heater beam pattern corresponds to a threshold electric field for FAI of between 0.1 and 0.01V/m. Differences between field-aligned and vertical propagation heating are also presented.

scholarly journals Saturation and hysteresis effects in ionospheric modification experiments observed by the CUTLASS and EISCAT radars

2006 ◽  
Vol 24 (2) ◽  
pp. 543-553 ◽  
Author(s):  
D. M. Wright ◽  
J. A. Davies ◽  
T. K. Yeoman ◽  
T. R. Robinson ◽  
H. Shergill
Keyword(s):  
High Frequency ◽  
Radio Waves ◽  
Heating Facility ◽  
Ionospheric Modification ◽  
Radiated Power ◽  
Pump Waves ◽  
Hybrid Waves ◽  
Electron Density Irregularities ◽  
Uhf Radar ◽  
Field Aligned Irregularities

Abstract. The results of high latitude ionospheric modification experiments utilising the EISCAT heating facility at Tromsø are presented. As a result of the interaction between the high power pump waves and upper hybrid waves in the ionosphere, field-aligned electron density irregularities are artificially excited. Observations of these structures with the CUTLASS coherent HF radars and the EISCAT incoherent UHF radar exhibit hysteresis effects as the heater output power is varied. These are explained in terms of the two-stage mechanism which leads to the growth of the irregularities. Experiments which involve preconditioning of the ionosphere also indicate that hysteresis could be exploited to maximise the intensity of the field-aligned irregularities, especially where the available heater power is limited. In addition, the saturation of the irregularity amplitude is considered. Although, the rate of irregularity growth becomes less rapid at high heater powers it does not seem to fully saturate, indicating that the amplification would continue beyond the capabilities of the Tromsø heater - currently the most powerful of its kind. It is shown that the CUTLASS radars are sensitive to irregularities produced by very low heater powers (effective radiated powers <4 MW). This fact is discussed from the perspective of a new heating facility, SPEAR, located on Spitzbergen and capable of transmitting high frequency radio waves with an effective radiated power ~10% of that of the Tromsø heater (28MW).

scholarly journals History of the Tromsø Ionosphere Heating facility

2021 ◽  
Author(s):  
Michael T. Rietveld ◽  
Peter Stubbe
Keyword(s):  
Historical Background ◽  
Incoherent Scatter Radar ◽  
Max Planck ◽  
Ionospheric Heating ◽  
Heating Facility ◽  
Incoherent Scatter ◽  
Scatter Radar ◽  
History Of ◽  
New Generation ◽  
Near Future

Abstract. We present the historical background to the construction of a major ionospheric heating facility near Tromsø, Norway in the 1970s by the Max Planck Institute for Aeronomy and the subsequent operational history to the present. It was built next to the EISCAT incoherent scatter radar facility and in a region with a multitude of diagnostic instruments used to study the auroral region. The facility was transferred to the EISCAT Scientific Association in January 1993 and continues to provide new discoveries in plasma physics and ionospheric and atmospheric science to this day. It is expected that ‘Heating’ will continue operating together with the new generation of incoherent scatter radar, called EISCAT_3D, when it is commissioned in the near future.

scholarly journals Meteor studies applying incoherent scatter radar instruments

2012 ◽  
Vol 10 (H16) ◽  
pp. 181-181
Author(s):  
Ingrid Mann ◽  
Asta Pellinen-Wannberg ◽  
Anders Tjulin
Keyword(s):  
Interplanetary Space ◽  
Spectral Composition ◽  
Optical Emission ◽  
Mean Free Path ◽  
Solid Particles ◽  
Radio Waves ◽  
Incoherent Scatter Radar ◽  
Atmospheric Species ◽  
Incoherent Scatter ◽  
Scatter Radar

AbstractOne of the interesting aspects of optical meteor studies is that the spectral composition of the brightness reveals information about the element composition of the solid particles that enter Earthfs atmosphere from interplanetary space. Deriving composition from optical spectra requires understanding the entry process during which the entering solid interacts with atmospheric species. This is especially so, because most meteors are observed at altitudes where the mean free path changes from tens of meters to millimeters, that is in the 120 km to 80 km altitude range within the atmosphere. The ionization that causes optical emission also reflects radio waves, so that meteors are observed with different kinds of radar instruments. Incoherent scatter radar facilities are in particular designed to study the upper atmosphere by using the backscattering from free electrons and are basically High Power Large Aperture radars. During the past 15 years they have been increasingly used for meteor studies. The phased-array incoherent scatter radars that are currently under development, such as the planned EISCAT-3Dsystem in northern Scandinavia, will further improve the spatial and time resolution of radar observations and will allow simultaneous measurements of the meteors and of the parameters of the surrounding ionosphere. Radar backscattering is also sensitive to objects that are smaller than those detected optically, so that the observations also permit studying the extension of the meteoroid size distribution to smaller sizes. In this presentation we consider the possibilities for measurements with the future EISCAT-3D as a new path of studying the physics of meteor phenomena with high accuracy.

scholarly journals Stimulated Brillouin scattering during electron gyro-harmonic heating at EISCAT

2015 ◽  
Vol 33 (8) ◽  
pp. 983-990 ◽  
Author(s):  
H. Y. Fu ◽  
W. A. Scales ◽  
P. A. Bernhardt ◽  
S. J. Briczinski ◽  
M. J. Kosch ◽  
...  
Keyword(s):  
High Frequency ◽  
Brillouin Scattering ◽  
Electromagnetic Emission ◽  
Spectral Lines ◽  
Radio Waves ◽  
Pump Frequency ◽  
Incoherent Scatter ◽  
Ionospheric Modification ◽  
Stimulated Brillouin ◽  
Uhf Radar

Abstract. Observations of secondary radiation, stimulated electromagnetic emission (SEE), produced during ionospheric modification experiments using ground-based, high-power, high-frequency (HF) radio waves are considered. The High Frequency Active Auroral Research Program (HAARP) facility is capable of generating narrowband SEE in the form of stimulated Brillouin scatter (SBS) and stimulated ion Bernstein scatter (SIBS) in the SEE spectrum. Such narrowband SEE spectral lines have not been reported using the European Incoherent Scatter (EISCAT) heater facility before. This work reports the first EISCAT results of narrowband SEE spectra and compares them to SEE previously observed at HAARP during electron gyro-harmonic heating. An analysis of experimental SEE data shows observations of emission lines within 100 Hz of the pump frequency, interpreted as SBS, during the 2012 July EISCAT campaign. Experimental results indicate that SBS strengthens as the pump frequency approaches the third electron gyro-harmonic. Also, for different heater antenna beam angles, the CUTLASS radar backscatter induced by HF radio pumping is suppressed near electron gyro-harmonics, whereas electron temperature enhancement weakens as measured by EISCAT/UHF radar. The main features of these new narrowband EISCAT observations are generally consistent with previous SBS measurements at HAARP.

scholarly journals Ducting of incoherent scatter radar waves by field-aligned irregularities

2020 ◽  
Author(s):  
Michael T. Rietveld ◽  
Andrew Senior
Keyword(s):  
Electron Density ◽  
Large Scale ◽  
Physical Mechanism ◽  
Future Research ◽  
Incoherent Scatter Radar ◽  
Incoherent Scatter ◽  
Scatter Radar ◽  
Induced Field ◽  
The Magnetic Field ◽  
Field Aligned Irregularities

Abstract. We provide an explanation for a mysterious phenomenon that has been recognized in recent years in EISCAT UHF incoherent scatter radar (ISR) measurement during many high power HF ionospheric pumping experiments. The phenomenon is an apparent increase in electron density observed above the HF reflection altitude, extending up to the observable limits usually in the range 400–650 km, as shown in several publications in recent years. It was shown by Senior et al. (2013) that several examples of these enhanced backscatter could not be explained by increases in electron density. A summary of characteristics of the backscatter enhancements is presented as well as the results of a survey of events. We propose that medium- to large-scale HF-induced field-aligned irregularities (tens to hundreds of m scale) act to refract the radar signals along the magnetic field, thereby acting as a guide so that the free-space r2 spreading of the signals no longer applies. The nature of the irregularities and the physical mechanism of their production by powerful HF waves is an exciting topic for future research since, surprisingly, they appear to be preferentially excited by X-mode waves. The explanation proposed here involving HF-induced irregularities may well apply to other ISR observations of the ionosphere in the presence of specific natural irregularities.

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