HF radar observations of decaying artificial field-aligned irregularities

1996 ◽  
Vol 101 (A12) ◽  
pp. 26981-26993 ◽  
Author(s):  
D. L. Hysell ◽  
M. C. Kelley ◽  
Y. M. Yampolski ◽  
V. S. Beley ◽  
A. V. Koloskov ◽  
...  
Keyword(s):  
Hf Radar ◽  
Radar Observations ◽  
Field Aligned Irregularities

scholarly journals Blending Surface Currents from HF Radar Observations and Numerical Modeling: Tidal Hindcasts and Forecasts

2015 ◽  
Vol 32 (2) ◽  
pp. 256-281 ◽  
Author(s):  
E. V. Stanev ◽  
F. Ziemer ◽  
J. Schulz-Stellenfleth ◽  
J. Seemann ◽  
J. Staneva ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
German Bight ◽  
Spatial Scales ◽  
Surface Current ◽  
Hf Radar ◽  
Optimal Interpolation ◽  
Kelvin Wave ◽  
Arctic Seas ◽  
Current Estimate ◽  
Radar Observations

AbstractAn observation network operating three Wellen Radars (WERAs) in the German Bight, which are part of the Coastal Observing System for Northern and Arctic Seas (COSYNA), is presented in detail. Major consideration is given to expanding the patchy observations over the entire German Bight on a 1-km grid and producing state estimates at intratidal scales, and 6- and 12-h forecasts. This was achieved with the help of the proposed spatiotemporal optimal interpolation (STOI) method, which efficiently uses observations and simulations from a free model run within an analysis window of one or two tidal cycles. In this way the method maximizes the use of available observations and can be considered as a step toward the “best surface current estimate.” The performance of the analysis was investigated based on the achieved reduction of the misfit between model and observations. The complex dynamics of the study domain was illustrated based on the spatial and temporal changes of tidal ellipses for the M2 and M4 constituents from HF radar observations. It was demonstrated that blending observations and numerical modeling facilitates physical interpretation of processes such as the nonlinear distortion of the Kelvin wave in the coastal zone and in particular in front of the Elbe and Weser estuaries. Comparisons with in situ data acquired outside the area covered by the HF radar demonstrated that the analysis method is able to propagate the HF radar information to larger spatial scales.

scholarly journals Multi-frequency HF radar measurements of artificial F-region field-aligned irregularities

2004 ◽  
Vol 22 (10) ◽  
pp. 3503-3511 ◽  
Author(s):  
A. Senior ◽  
N. D. Borisov ◽  
M. J. Kosch ◽  
T. K. Yeoman ◽  
F. Honary ◽  
...  
Keyword(s):  
Wave Interaction ◽  
Operating Mode ◽  
Hf Radar ◽  
Heating Facility ◽  
F Region ◽  
Density Perturbations ◽  
Radar Measurements ◽  
The Mean ◽  
Power Measurements ◽  
Field Aligned Irregularities

Abstract. We present radar backscatter power measurements using the CUTLASS HF radar at Hankasalmi, Finland from F-region field-aligned irregularities induced by HF radio pumping with the EISCAT Heating facility. A novel radar operating mode is used in which the radar frequency is rapidly swept through a number of bands, making use of the varying ionospheric refraction to probe different heights within the heated region. We obtain height profiles of backscatter power which correspond to e-folding scale lengths of around 20km for the mean-square electron density perturbations for pump wave interaction heights in the region of 240-250km in daytime conditions. The results are in agreement with previous measurements made by other techniques. We discuss some problems with the method and suggest improvements for future experiments.

Assessing SARAL/AltiKa Data in the Coastal Zone: Comparisons with HF Radar Observations

2015 ◽  
Vol 38 (sup1) ◽  
pp. 260-276 ◽  
Author(s):  
Ananda Pascual ◽  
Arancha Lana ◽  
Charles Troupin ◽  
Simón Ruiz ◽  
Yannice Faugère ◽  
...  
Keyword(s):  
Coastal Zone ◽  
Hf Radar ◽  
Radar Observations

scholarly journals Statistical observations of the MLT, latitude and size of pulsed ionospheric flows with the CUTLASS Finland radar

1999 ◽  
Vol 17 (7) ◽  
pp. 855-867 ◽  
Author(s):  
G. Provan ◽  
T. K. Yeoman
Keyword(s):  
Hf Radar ◽  
High Time Resolution ◽  
Plasma Convection ◽  
Unified Framework ◽  
Coherent Scatter ◽  
Radar Observations ◽  
Scatter Radar ◽  
Precipitation Regimes ◽  
Low Altitude ◽  
Flux Transfer

Abstract. A study has been performed on the occurrence of pulsed ionospheric flows as detected by the CUTLASS Finland HF radar. These flows have been suggested as being created at the ionospheric footprint of newly-reconnected field lines, during episodes of magnetic flux transfer into the terrestrial magnetosphere (flux transfer events or FTEs). Two years of both high-time resolution and normal scan data from the CUTLASS Finland radar have been analysed in order to perform a statistical study of the extent and location of the pulsed ionospheric flows. We note a great similarity between the statistical pattern of the coherent radar observations of pulsed ionospheric flows and the traditional low-altitude satellite identification of the particle signature associated with the cusp/cleft region. However, the coherent scatter radar observations suggest that the merging gap is far wider than that proposed by the Newell and Meng model. The new model for cusp low-altitude particle signatures, proposed by Lockwood and Onsager and Lockwood provides a unified framework to explain the dayside precipitation regimes observed both by the low-altitude satellites and by coherent scatter radar detection.Key words. Magnetospheric physics (magnetosphere · ionosphere interactions; plasma convection; solar wind-magnetosphere interactions)

scholarly journals Excitation thresholds of field-aligned irregularities and associated ionospheric hysteresis at very high latitudes observed using SPEAR-induced HF radar backscatter

2009 ◽  
Vol 27 (7) ◽  
pp. 2623-2631 ◽  
Author(s):  
D. M. Wright ◽  
R. S. Dhillon ◽  
T. K. Yeoman ◽  
T. R. Robinson ◽  
E. C. Thomas ◽  
...  
Keyword(s):  
Hf Radar ◽  
High Latitudes ◽  
Plasma Parameters ◽  
Power Cycle ◽  
Incoherent Scatter ◽  
Radiated Power ◽  
Induced Field ◽  
High Latitude Ionosphere ◽  
Very High ◽  
Field Aligned Irregularities

Abstract. On 10 October 2006 the SPEAR high power radar facility was operated in a power-stepping mode where both CUTLASS radars were detecting backscatter from the SPEAR-induced field-aligned irregularities (FAIs). The effective radiated power of SPEAR was varied from 1–10 MW. The aim of the experiment was to investigate the power thresholds for excitation (Pt) and collapse (Pc) of artificially-induced FAIs in the ionosphere over Svalbard. It was demonstrated that FAI could be excited by a SPEAR ERP of only 1 MW, representing only 1/30th of SPEAR's total capability, and that once created the irregularities could be maintained for even lower powers. The experiment also demonstrated that the very high latitude ionosphere exhibits hysteresis, where the down-going part of the power cycle provided a higher density of irregularities than for the equivalent part of the up-going cycle. Although this second result is similar to that observed previously by CUTLASS in conjunction with the Tromsø heater, the same is not true for the equivalent incoherent scatter measurements. The EISCAT Svalbard Radar (ESR) failed to detect any hysteresis in the plasma parameters over Svalbard in stark contract with the measurements made using the Tromsø UHF.

scholarly journals Estimation of currents using SARAL/AltiKa in the coastal regions of India

2014 ◽  
Vol XL-8 ◽  
pp. 1365-1367
Author(s):  
A. Chaudhary ◽  
N. Agarwal ◽  
R. Sharma
Keyword(s):  
High Frequency ◽  
Coastal Region ◽  
Hf Radar ◽  
Altimeter Data ◽  
Surface Currents ◽  
Radar Observations ◽  
Geostrophic Currents ◽  
The Moment ◽  
Track Surface ◽  
Along Track

The present study explores the possibility of deriving the across track currents along the Indian coastal region from SARAL/AltiKa mission. The across track surface geostrophic currents obtained from along track SARAL altimeter data are directly compared (qualitatively) with high frequency (HF) radar observations of surface currents in the Bay of Bengal. The velocity component from HF radar which is perpendicular to the altimeter tracks is considered. Since the ageostrophic velocity contribution is ignored for the moment, the surface geostrophic currents SARAL compare well only under low wind conditions. Due to high along track resolution of SARAL there are large variations in velocity which are not captured by the HF radar observations. In general, the magnitude and variations in surface currents derived from SARAL altimeter are comparable with HF radar observations.

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