scholarly journals History of the Super Dual Auroral Radar Network (SuperDARN)-I: pre-SuperDARN developments in high frequency radar technology for ionospheric research and selected scientific results

2021 ◽  
Vol 12 (1) ◽  
pp. 77-93
Author(s):  
Raymond A. Greenwald
Keyword(s):  
Plasma Density ◽  
High Frequency ◽  
Auroral Zone ◽  
Hf Radar ◽  
Plasma Convection ◽  
Very High Frequency ◽  
High Frequency Radar ◽  
F Region ◽  
Convection Patterns ◽  
Scientific Results

Abstract. Part I of this history describes the motivations for developing radars in the high frequency (HF) band to study plasma density irregularities in the F region of the auroral zone and polar cap ionospheres. French and Swedish scientists were the first to use HF frequencies to study the Doppler velocities of HF radar backscatter from F-region plasma density irregularities over northern Sweden. These observations encouraged the author of this paper to pursue similar measurements over northeastern Alaska, and this eventually led to the construction of a large HF-phased-array radar at Goose Bay, Labrador, Canada. This radar utilized frequencies from 8–20 MHz and could be electronically steered over 16 beam directions, covering a 52∘ azimuth sector. Subsequently, similar radars were constructed at Schefferville, Quebec, and Halley Station, Antarctica. Observations with these radars showed that F-region backscatter often exhibited Doppler velocities that were significantly above and below the ion-acoustic velocity. This distinguished HF Doppler measurements from prior measurements of E-region irregularities that were obtained with radars operating at very high frequency (VHF) and ultra-high frequency (UHF). Results obtained with these early HF radars are also presented. They include comparisons of Doppler velocities observed with HF radars and incoherent scatter radars, comparisons of plasma convection patterns observed simultaneously in conjugate hemispheres, and the response of these patterns to changes in the interplanetary magnetic field, transient velocity enhancements in the dayside cusp, preferred frequencies for geomagnetic pulsations, and observations of medium-scale atmospheric gravity waves with HF radars.

scholarly journals Orientation of the cross-field anisotropy of small-scale ionospheric irregularities and direction of plasma convection

2005 ◽  
Vol 23 (4) ◽  
pp. 1227-1237 ◽  
Author(s):  
E. D. Tereshchenko ◽  
N. Yu. Romanova ◽  
A. V. Koustov
Keyword(s):  
Auroral Zone ◽  
Small Scale ◽  
Plasma Convection ◽  
Polar Cap ◽  
F Region ◽  
Radio Signals ◽  
The Cross ◽  
Satellite Radar ◽  
Convection Patterns ◽  
The Relationship

Abstract. The relationship between the orientation of the small-scale ionospheric irregularity anisotropy in a plane perpendicular to the geomagnetic field and the direction of plasma convection in the F region is investigated. The cross-field anisotropy of irregularities is obtained by fitting theoretical expectations for the amplitude scintillations of satellite radio signals to the actual measurements. Information on plasma convection was provided by the SuperDARN HF radars. Joint satellite/radar observations in both the auroral zone and the polar cap are considered. It is shown that the irregularity cross-field anisotropy agrees quite well with the direction of plasma convection with the best agreement for events with quasi-stationary convection patterns.

Low‐angle tracking algorithm using polarisation sensitive array for very‐high frequency radar

2014 ◽  
Vol 8 (9) ◽  
pp. 1035-1041 ◽  
Author(s):  
Zhen‐hai Xu ◽  
Jia‐ni Wu ◽  
Ziyuan Xiong ◽  
Shun‐ping Xiao
Keyword(s):  
High Frequency ◽  
Tracking Algorithm ◽  
Very High Frequency ◽  
High Frequency Radar ◽  
Angle Tracking ◽  
Very High

scholarly journals Simultaneous HF measurements of E- and F-region Doppler velocities at large flow angles

2004 ◽  
Vol 22 (4) ◽  
pp. 1177-1185 ◽  
Author(s):  
R. A. Makarevitch ◽  
F. Honary ◽  
A. V. Koustov
Keyword(s):  
Hf Radar ◽  
Doppler Velocity ◽  
Plasma Convection ◽  
Aspect Angle ◽  
F Region ◽  
Significant Difference ◽  
E Region ◽  
The Difference ◽  
New Feature ◽  
Large Flow

Abstract. Data collected by the CUTLASS Finland HF radar are used to illustrate the significant difference between the cosine component of the plasma convection in the F-region and the Doppler velocity of the E-region coherent echoes observed at large flow angles. We show that the E-region velocity is ~5 times smaller in magnitude and rotated by ~30° clockwise with respect to convection in the F-region. Also, measurements at flow angles larger than 90° exhibit a completely new feature: Doppler velocity increase with the expected aspect angle and spatial anticorrelation with the backscatter power. By considering DMSP drift-meter measurements we argue that the difference between F- and E-region velocities cannot be interpreted in terms of the convection change with latitude. The observed features in the velocity of the E-region echoes can be explained by taking into account the ion drift contribution to the irregularity phase velocity as predicted by the linear fluid theory. Key words. Ionosphere (auroral ionosphere; ionospheric irregularities; plasma convection)

Lagrangian dynamics in the Gulf of Trieste from high resolution HF-Radar

2020 ◽  
Author(s):  
Nydia Catalina Reyes-Suarez ◽  
Ismael Hernandez-Carrasco ◽  
Matjaz Licer ◽  
Vanessa Cardin ◽  
Miroslav Gacic ◽  
...  
Keyword(s):  
High Frequency ◽  
Oil Spills ◽  
Hf Radar ◽  
Time Data ◽  
High Frequency Radar ◽  
Gulf Of Trieste ◽  
Radar Network ◽  
Marine Traffic ◽  
Surface Variability ◽  
Lagrangian Descriptors

<p>The Gulf of Trieste (GoT) is shared by Italy, Slovenia and Croatia, with most of its coasts belonging to Italy and Slovenia, along with the two main harbours; the Harbour of Trieste (Italy) and Koper (Slovenia). Both are subject to heavy marine traffic and exposed to different threats including oil spills, maritime accidents and SAR operations. The GOT High frequency radar network provides near-real time data of sea surface currents and waves since 2016. In this work we provide a statistical description of surface variability in terms of Lagrangian descriptors in order to elucidate the transport and retention in the GoT as well as to provide the seasonal evolution of the residence time. Among the most widely used Lagrangian techniques, we focus the study on Lagrangian Coherent Structures and Path-integrated topological variables like Lagrangian divergence and Lagrangian vorticity. </p>

Performance Evaluation of SeaSonde High-Frequency Radar for Vessel Detection

2011 ◽  
Vol 45 (3) ◽  
pp. 14-24 ◽  
Author(s):  
Hugh J. Roarty ◽  
Erick Rivera Lemus ◽  
Ethan Handel ◽  
Scott M. Glenn ◽  
Donald E. Barrick ◽  
...  
Keyword(s):  
High Frequency ◽  
Processing Parameters ◽  
Hf Radar ◽  
High Frequency Radar ◽  
Detection And Tracking ◽  
Surface Vessels ◽  
Wave Radar ◽  
Vessel Detection ◽  
Track Surface ◽  
Maritime Domain Awareness

AbstractHigh-frequency (HF) surface wave radar has been identified to be a gap-filling technology for Maritime Domain Awareness. Present SeaSonde HF radars have been designed to map surface currents but are able to track surface vessels in a dual-use mode. Rutgers and CODAR Ocean Sensors, Ltd., have collaborated on the development of vessel detection and tracking capabilities from compact HF radars, demonstrating that ships can be detected and tracked by multistatic HF radar in a multiship environment while simultaneously mapping ocean currents. Furthermore, the same vessel is seen simultaneously by the radar based on different processing parameters, mitigating the need to preselect a fixed set and thereby improving detection performance.

The response of the thermosphere and ionosphere to magnetospheric forcing

1989 ◽  
Vol 328 (1598) ◽  
pp. 139-171 ◽  
Keyword(s):  
Electric Fields ◽  
Plasma Density ◽  
Large Scale ◽  
Data Sets ◽  
Polar Regions ◽  
Ionospheric Model ◽  
Plasma Convection ◽  
Geomagnetic Disturbances ◽  
F Region ◽  
Wide Range

During the past six years, rapid advances in three observational techniques (groundbased radars, optical interferometers and satellite-borne instruments) have provided a means of observing a wide range of spectacular interactions between the coupled magnetosphere, ionosphere and thermosphere system. Perhaps the most fundamental gain has come from the combined data-sets from the NASA Dynamics Explorer ( DE ) Satellites. These have unambiguously described the global nature of thermospheric flows, and their response to magnetospheric forcing. The DE spacecraft have also described, at the same time, the magnetospheric particle precipitation and convective electric fields which force the polar thermosphere and ionosphere. The response of the thermosphere to magnetospheric forcing is far more complex than merely the rare excitation of 1 km s -1 wind speeds and strong heating; the heating causes large-scale convection and advection within the thermosphere. These large winds grossly change the compositional structure of the upper thermosphere at high and middle latitudes during major geomagnetic disturbances. Some of the major seasonal and geomagnetic storm-related anomalies of the ionosphere are directly attributable to the gross windinduced changes of thermospheric composition; the mid-latitude ionospheric storm ‘negative phase’, however, is yet to be fully understood. The combination of very strong polar wind velocities and rapid plasma convection forced by magnetospheric electric fields strongly and rapidly modify F-region plasma distributions generated by the combination of local solar and auroral ionization sources. Until recently, however, it has been difficult to interpret the observed complex spatial and timedependent structures and motions of the thermosphere and ionosphere because of their strong and nonlinear coupling. It has recently been possible to complete a numerical and computational merging of the University College London (UCL) global thermospheric model and the Sheffield University ionospheric model. This has produced a self-consistent coupled thermospheric-ionospheric model, which has become a valuable diagnostic tool for examining thermospheric-ionospheric interactions in the polar regions. In particular, it is possible to examine the effects of induced winds, ion transport, and the seasonal and diurnal U.T. variations of solar heating and photoionization within the polar regions. Polar and high-latitude plasma density structure at F-region altitudes can be seen to be strongly controlled by U.T., and by season, even for constant solar and geomagnetic activity. In the winter, the F-region polar plasma density is generally dominated by the effects of transport of plasma from the dayside (sunlit cusp). In the summer polar region, however, an increase in the proportion of molecular to atomic species, created by the global seasonal circulation and augmented by the geomagnetic forcing, controls the plasma composition and generally depresses plasma densities at all U.Ts. A number of these complex effects can be seen in data obtained from ground-based radars, Fabry-Perot interferometers and in the combined DE data-sets. Several of these observations will be used, in combination with simulations using the UCL-Sheffield coupled model, to illustrate the major features of large-scale thermosphere-ionosphere interactions in response to geomagnetic forcing.

scholarly journals A new Lagrangian-based short-term prediction methodology for high-frequency (HF) radar currents

Ocean Science ◽  
2021 ◽  
Vol 17 (3) ◽  
pp. 755-768
Author(s):  
Lohitzune Solabarrieta ◽  
Ismael Hernández-Carrasco ◽  
Anna Rubio ◽  
Michael Campbell ◽  
Ganix Esnaola ◽  
...  
Keyword(s):  
Real Time ◽  
High Frequency ◽  
Skill Score ◽  
Hf Radar ◽  
Surface Currents ◽  
Short Term ◽  
High Frequency Radar ◽  
Term Prediction ◽  
Short Term Prediction ◽  
Temporal Horizon

Abstract. The use of high-frequency radar (HFR) data is increasing worldwide for different applications in the field of operational oceanography and data assimilation, as it provides real-time coastal surface currents at high temporal and spatial resolution. In this work, a Lagrangian-based, empirical, real-time, short-term prediction (L-STP) system is presented in order to provide short-term forecasts of up to 48 h of ocean currents. The method is based on finding historical analogs of Lagrangian trajectories obtained from HFR surface currents. Then, assuming that the present state will follow the same temporal evolution as the historical analog, we perform the forecast. The method is applied to two HFR systems covering two areas with different dynamical characteristics: the southeast Bay of Biscay and the central Red Sea. A comparison of the L-STP methodology with predictions based on persistence and reference fields is performed in order to quantify the error introduced by this approach. Furthermore, a sensitivity analysis has been conducted to determine the limit of applicability of the methodology regarding the temporal horizon of Lagrangian prediction. A real-time skill score has been developed using the results of this analysis, which allows for the identification of periods when the short-term prediction performance is more likely to be low, and persistence can be used as a better predictor for the future currents.

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